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Module II

AAEC 4984

Spring 2009

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The Basics of Food, Nutrition, and Health ......................................................................... 1

A. Nutrients and Nutrition ............................................................................................. 1 1. Why Should We Care About Nutrition?................................................................. 1 2. What Are the Nutrients in Foods? .......................................................................... 3 3. What Constitutes a Nutritious Diet? ..................................................................... 14

B. Foods and Nutrition.................................................................................................. 19 Food Classifications and Guidelines......................................................................... 23

C. Nutrient and Food Recommendations..................................................................... 25 MyPyramid ............................................................................................................... 33 Food Labels: Required Items .................................................................................... 36 Food Labels: Optional Items..................................................................................... 39

D. Diet and Health ....................................................................................................... 43 Diet and Cardiovascular Disease .............................................................................. 46 Diet and Cancer......................................................................................................... 50

E. A Foreshadowing Conclusion .................................................................................. 52

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The Basics of Food, Nutrition, and Health

In this module we review the basics of food, nutrition, and health as can be found in most

introductory nutrition books. There are many good introductory nutrition texts and for

this review we draw heavily from the textbook by Frances Sizer and Ellie Whitney

entitled Nutrition: Concepts and Controversies 11th Edition. Thomson-Wadsworth 2008.

We begin with a review of nutrients and then turn to the connection of nutrients to food,

and then the connection to health.

A. Nutrients and Nutrition

This sub-section is designed to answer three rather basic questions:

1. Why should we care about nutrition?

2. What are the nutrients in foods?

3. What constitutes a nutritious diet?

1. Why Should We Care About Nutrition?

The simple answer to this question is that there is a well established link between

nutrition and several chronic diseases. A chronic disease is defined as a long-duration

degenerative disease characterized by deterioration of the body organs. According to the

National Center for Health Statistics, the top 10 causes of death in 2005 are as listed in

table 1. Of these top 10 causes of death, the top three (i.e., Heart Disease, Cancers, and

Strokes), as well as Diabetes (No. 6), are known to be affected by diet.

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Table 1. Leading Causes of Death for U.S. 2005 Cause of death Deaths All causes 2,448,017 Heart Diseases 652,091 Cancers 559,312 Strokes 143,579 Chronic lower respiratory diseases 130,933 Unintentional injuries 117,809 Diabetes mellitus 75,119 Alzheimer's disease 71,599 Influenza and pneumonia 63,001 Nephritis, nephrotic syndrome and nephrosis 43,901 Septicemia 34,136

Source: Health United States, 2007. US Dept. of Health and Human Services

In percentage terms, these four disease categories accounted for over half of the deaths

(59%) in the United States in 2005 with the breakdown being: heart diseases 27%,

cancers 23%, strokes 6%, and diabetes 3%.

Because these diseases are known to be related to diet, the implication is that by

altering the diet, the risk of contracting and/or dying from these diseases may be altered

as well. Consequently, the risk of contracting and dying from these diseases will be

increased by consuming one type of diet whereas the risk can be decreased by consuming

another type of diet.

What do we mean by the term diet? We will define diet to be the foods and beverages

a person usually eats or drinks. A diet is not the foods and beverages for a single meal.

A happy meal from McDonald’s is not a diet. A diet is more like a “typical” or

“average” meal a person may eat over say a week or a month. Note however, in a typical

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Wal Mart Superstore grocery section there are over 30,000 different food items. It is

impractical and also irrelevant to try to classify diets based on food items because what is

important for the body and health are the basic components of the foods, called nutrients,

which are much fewer in number than the number of food items.

2. What Are the Nutrients in Foods?

Technically, nutrients are families of molecules in food or components of food that are

indispensible for the functioning of the body. Conceptually, nutrients are just attributes

or characteristics that are common to all foods and thus are useful as a classification

scheme for foods that may seem very different, such as apples and oranges.

Consequently a diet also could be defined as the foods and beverages or nutrients a

person usually eats or drinks.

The body requires six kinds of nutrients or nutrient classes: 1

1. Water 4. Proteins

2. Carbohydrates 5. Vitamins

3. Fats 6. Minerals

Water needs no introduction or definition. Carbohydrates are compounds that are

composed of sugars. They can be classified by their number of sugar units: one unit

(monosaccharides such as glucose and fructose), two units (disaccharides such as sucrose

and lactose) and multiple units (polysaccachrides such as starch, glycogen, and cellulose).

Fats are lipids (organic compounds soluble in organic solvents but not water) that are

solid at the room temperature of 70o F. Fats are usually further broken down into

1 A typical Nutrition textbook will have individual chapters devoted to each of the nutrient classes with a discussion of the chemical elements and compounds for each and how these are processed by body. This decompositional detail is not viewed as critical for the main purpose of this review.

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saturated fatty acids and unsaturated fatty acids. The difference has to do with how the

hydrocarbon chains are connected. Proteins are organic compounds consisting of amino

acids that are joined by peptide bonds. Vitamins are organic compounds that are vital to

life and indispensible to body functions but only needed in minute amounts. There are 14

vitamins: Vitamin A, Thiamin B1, Riboflavin B2, Niacin B3, Vitamin B6, Vitamin B12,

Biotin, Pantothenic acid, Vitamin C, Vitamin D, Vitamin E, Vitamin K, Folate, and

Choline. Finally, minerals are naturally occurring, inorganic, homogeneous substances

or chemical elements. There are 15 minerals of main concern for nutrition: calcium,

chromium, copper, fluoride, iodine, iron, magnesium, manganese, molybdenum,

phosphorous, selenium, zinc, potassium, sodium, and chloride.2 The first four nutrient

classes are required in relatively large amounts and are called macronutrients. Vitamins

and minerals are required in much smaller quantities and are called micronutrients. The

micronutrients, vitamins and minerals do not provide energy but act as regulators in the

body. Vitamins and minerals assist in numerous body processes, such as digesting food,

moving muscles, disposing of waste, growing new tissue and healing wounds.

Note because all foods have these six nutrients in some percentage (remembering

zero is also a percentage) a diet could also be defined as the usual combination of

nutrients an individual consumes. All six classes of nutrients have what are called

essential nutrients. Essential nutrients are nutrients the body cannot make for itself

from other raw materials and must be obtained from food to prevent deficiencies.

With the exception of Water, the macronutrients provide fuel or energy for the body

to function. Energy is defined as the capacity to do work. Food energy is measured in

calories. A calorie (short for kilocalorie) is technically defined as the amount of heat 2 These are the minerals listed in the DRI tables. See next section for discussion of DRI.

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energy necessary to raise the temperature of a kilogram (one liter) of water one degree

Celsius. For a standard weight the macronutrients (excluding water) each provides a

certain calorie or amount of energy. The standard unit of weight used in nutrition is the

gram(g), which is defined as the weight of a milliliter (ml) of water with defined

conditions of temperature and pressure. One gram equals about .04 ounces or 28 grams

equals about 1 ounce. Carbohydrates and Proteins each provide 4 calories per gram,

whereas Fats provide 9 calories per gram. Table 2 provides a succinct classification of

the nutrient classes.

Table 2. Main Nutrient Classes 6 Nutrient Classes Macro Micro Energy Yielding Cal/g

1. Water X 2. Carbohydrate X X 4 3. Fat (Lipids) X X 9 4. Protein X X 4 5. Vitamins X 6. Minerals X

Individual Food Items: Nutrient and Energy Characteristics

Knowing the calories per gram of the nutrients allows the total energy or calories per

food item to be calculated by the formula,

Calories = 4×Carbohydrates in grams + 4×Protein in grams + 9×Fat in grams.

While this equation is useful it is a little cumbersome to work with so let’s exercise our

brains and use a little more sophisticated but simplifying notation. Let Ni denote the

amount of nutrient i measured in grams. So, NC = Carbohydrates in grams,

NP = Protein in grams, and NF = Carbohydrates in grams. Using this shorthand notation

(aka known as variable notation) rewrite the equation as

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(1) 4 4 9 C PCals N N N= × + × + × F

FN

.

There are two important facts related to this equation to remember.

1. If we know the amount of carbohydrates (NC), fats (NF), and protein (NP) in a food

item we can calculate the amount of energy or calories (cals) in the food item.

For example, if a food item has 40 grams of carbohydrates (NC = 40), 30 grams of protein

(NP = 30), and 20 grams of fat (NF = 20) then substituting into equation (1) we get 460 =

4 × 40 + 4 × 30 + 9 × 20.

2. There are substitution possibilities between nutrients holding calories constant. Stated

alternatively, there are tradeoffs between carbohydrates, fats, and protein for the same

energy level.

To see this lets rewrite equation (1) by solving for one of the nutrients (i.e., place one of

the nutrients on the left side of the equal sign). Suppose we solve equation (1) for NC.

Recall from basic algebra we first subtract from both sides 4 9PN× + × , which gives

4 9 4P FCals N N N− × − × = × .C Now divide through both sides by 4 to yield

9 4 4C P

CalsN N= − − FN

FN

. Writing this in decimal form gives

(2) .25 2.25C PN Cals N= × − − × .

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Equation (2) is useful for two things. First, if you tell me the amount of calories, protein,

and fat in a food item, I can use equation (2) to determine the amount of carbohydrates in

the item. For example, suppose Cals = 200, NP = 20, and NF = 10, then from using (2)

we know NC = 7.5. Second, we can use equation (2) to determine the tradeoff between

carbohydrates and either calories, protein, or fat, holding all else constant. For example,

equation (2) tells us that if we want to keep the calories and fat constant, if we increase

protein by one gram we must decrease carbohydrates by one gram. This should make

sense because carbohydrates and protein each have 4 grams of energy. What about the

tradeoff between carbohydrates and fat? Again, assuming calories and protein are held

constant, then if we increase the fat content by one unit we must decrease carbohydrates

by 2.25 grams. Can you derive the equations for Np and NF comparable to equation (2).

Consider table 3 below, which gives the energy yielding macronutrients for several

items.

Table 3. Selected Food items, Macronutrients, and Calories

Food Item  Quantity Weight(g) 

Carb (g) 

Prot (g) 

Fat (g) 

Energy (cals) 

Big Mac Hamburger  1 item  216  47  24  34  590 Raw carrots  1 c.  122  12  2  0  56 Coca‐Cola Classic  12 oz.  360  41  0  0  164 Boston Market Half Chicken,  w/ skin  1 item 

 277  4  70  33  593 

Using equation (1), the total number of calories for the Big Mac Hamburger is 590 =

4×47 + 4×24 + 9×34 and others are calculated the same way. Note that the Boston

Market Half Chicken with skin has basically the same number of calories as the Big Mac

but for different reason. While the Big Mac has 47 grams of carbohydrates, the chicken

has only 4. Alternatively, the chicken has 70 grams of protein whereas the Big Mac has

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24. This example demonstrates the second point: equivalent calories do not imply

equivalent macronutrient levels.

One problem with just looking at calories is the total number of grams (in weight) can

differ from one food item to another. For a simple example, two Big Macs would weigh

432 grams and have twice as many of all nutrients and grams. Alternatively, compare the

Big Mac to the Raw Carrots. The Big Mac weighs 216 grams whereas the Raw Carrots

weigh 122 grams. More informative measures of nutrients and energy can be created by

“normalizing” the measures, where normalize just means place on some common scale.

There are several different normalizations that are informative. For example we could

look at the contribution to total calories of each energy yielding nutrient by simply

dividing both sides of equation (1) by total calories and multiplying by 100 to yield

4 4 9(2) 100 100

4 4 4100 100 100 .

=

C P F

C P F

N N NCalories

N N NCalories Calories Calories

× + × + ×= ×

× × ×⎛ ⎞ ⎛ ⎞ ⎛ ⎞× + × + ×⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠ ⎝ ⎠

Each component of equation (2) is just a percentage so let’s define each component as the

nutrient density. That is nutrient density is the contribution to total calories provided by

the calories of an individual nutrient or for these nutrients in mathematical terms

4(3) 100 :CC

N ND Nutrient Density of CarbohydratesCals×

= ×

4(4) 100 :PP

N ND Nutrient Density of ProteinCals×

= ×

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9(5) 100 :FF

N ND Nutrient Density of FatsCals×

= ×

For example, the carbohydrate nutrient density scores for the above items are Big Mac

NDC (Big Mac)= 31.86 = [(4×47)/590]×100, NDC (Raw Carrots) = 85.71 = [(4×12)/56]×100,

NDC (Coca-Cola Classic) = 100 =[(4×41)/164]×100, and the NDC (Half Chicken) = 2.69 =

[(4×4)/593]×100. So on a per calories basis, the Coca-Cola classic has the highest

nutrient density for carbohydrates. The other nutrient density scores would be calculated

similarly. Note using this notation, equation (2) can be written more simply as

100 .C PND ND ND= + + F

An alternative normalization that is often encountered is energy density. Energy

density is defined as the ratio of total calories to total weight in grams or mathematically

(6) :fCalories in grams ED Energy Density of Food fWeight in grams

=

The energy densities for the above items are EDBig Mac = 2.73 = 590/216, EDRaw Carrots =

.46 = 56/122, ED Coca-Cola Classic = .45 = 164/360, and the ED Half Chicken = 2.14 = 593/277.

On a per gram basis the Big Mac and Half Chicken have an energy density about six

times greater than the raw carrots and the 12 ounce Coca-Cola. Table 4 summarizes the

nutrient and energy densities for the individual foods.

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Table 4. Selected Food items, Nutrient Densities and Energy Densities

Food Item  Quantity  NDC  NDP  NDF  ED Big Mac Hamburger  1 item  31.86 16.27 51.86 2.73 Raw carrots  1 c.  85.71 14.28 0 0.46 Coca‐Cola Classic  12 oz.  100 0 0 0.45 Boston Market Half Chicken,  w/ skin  1 item  2.69 47.21 50.084 2.14 

THINK BREAK!!!!!!:

Using the data in table 5 answer the following questions.

Table 5. Nutrient Characteristics of a Chick Fil-A Meal

Food Item  Quantity Weight(g) 

Carb (g) 

Prot (g) 

Fat (g) 

Chick Fil‐A Chicken Deluxe Sandwich  1 item 

 208  39  28  16 

Waffle potato fries (small)  1 item  85  37  3  5 Coca‐Cola Classic  12 oz.  360  41  0  0 

1. What is the total energy for each food item?

2. What is the energy density for each food item?

3. What is the nutrient density for carbohydrates for each item?

4. What is the nutrient density for protein for each item?

5. What is the nutrient density for fat for each item?

Meals: Nutrient and Energy Characteristics

Note from tables 3 and 4 the focus is on the characteristics of the individual food items.

However, using the information in table 3 we can also make similar calculations for a

meal.

Suppose Meal 1 consists of a Big Mac, 1 cup of raw carrots, and a 12 ounce Coca-

Cola and Meal 2 consists of the Half-Chicken, 1 cup of raw carrots, and a 12 ounce Coca-

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Cola. If we sum the appropriate numbers in the columns then we obtain the nutrition

characteristics of the meal as shown in table 6. For example, for Meal 1 the total weight

is 698 g = 216 g + 122 g + 360 g and the total carbohydrates is 100 g = 47 g + 12 g + 41

g. Table 6 gives the total weight, total nutrient contents, and energy for each meal.

Table 6. Nutritional Characteristics of Meals

Meal Weight(g) 

Carb 

(g) Prot (g) 

Fat (g) 

Energy (cals) 

Meal 1  (Big Mac, Carrots, Coke) 

 698 

 100 

 26 

 34 

 810 

Meal 2  (Chicken, Carrots, Coke) 

 759 

 57 

 72 

 33 

 813 

Though the total calories are comparable from these two meals the distribution of calories

stemming from the different macronutrients are very different. The main difference is

between carbohydrates and protein. Meal 1 has about twice as many carbohydrate grams

and about a third of the protein grams as Meal 2.

As with the individual foods we can also calculate the nutrient and energy densities.

By definition the nutrient density is the ratio of the nutrient in grams to the total energy in

grams. For Meal 1 the formula for carbohydrates is then

( )1

4 47 12 41100

810

49.4 : 1

C MealND

Nutrient Density of Carbohydrates in Meal

× + += ×

=

The other nutrient densities for Meal 1 (or Meal 2) can be calculated the same way.

Note the general formulas for the nutrient density for carbohydrates, protein, and fat for

Meal 1 are then

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Nutrient Density for Carbohydrates Meal 1

( )1 2 31

1

4(7) 100C food item C food item C food item

C MealMeal

N N NND

Cals× + +

= ×

Nutrient Density for Protein Meal 1

( )1 2 31

1

4(8) 100P food item P food item P food item

P MealMeal

N N NND

Cals× + +

= ×

Nutrient Density for Fats Meal 1

( )1 2 31

1

9(9) 100F food item F food item F food item

F MealMeal

N N NND

Cals× + +

= ×

Obviously we could do the same thing for Meal 2.

What about the energy density of the meals? No Problem. Recall the definition of

energy density is the ratio of total calories to total weight in grams. For Meal 1 this

would be

1590 56 164 1.16

698MealED + += =

and for Meal 2

256 164 593 1.07.

759MealED + += =

The general formula for the energy density of a meal is then

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1 2 3(10) : 1,2food item food item food itemMeal i

Meal i

Cals + Cals +Cals ED i

Weight Grams= =

Table 7 gives the nutrient and energy densities for the two meals.

Table 7. Nutrient and Energy Densities of Meals Meal  NDC  NDP  NDF  ED Meal 1  (Big Mac, Carrots, Coke) 

 49.4 

 12.8 

 37.8 

 1.16 

Meal 2  (Chicken, Carrots, Coke) 

 28.0 

 35.4 

 36.5 

 1.07 

Meal 1 is more dense in carbohydrates than Meal 2, but Meal 2 is more protein dense

than Meal 1. Meal 1 is slightly more energy dense than Meal 2.

WARNING!!!:

• The nutrient density of a meal is not equal to the sum of the individual food

item’s nutrient densities in the meal.

• The energy density of a meal is not equal to the sum of the individual food

item energy densities.

Note you cannot just sum up the numbers in table 4 and get the numbers in table 7. Can

you explain why?

THINK BREAK!!!!!!:

Using the data from table 5 on the Chick Fil-A meal (repeated below) to answer the

following questions.

Table 5. Nutrient Characteristics of a Chick Fil-A Meal

Food Item  Quantity Weight(g) 

Carb (g) 

Prot (g) 

Fat (g) 

Chick Fil‐A Chicken Deluxe Sandwich  1 item 

 208  39  28  16 

Waffle potato fries (small)  1 item  85  37  3  5 Coca‐Cola Classic  12 oz.  360  41  0  0 

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Assume the Chick Fil-A Meal is all three items:

1. What is the total energy for the meal?

2. What is the energy density for the meal?

3. What is the nutrient density for carbohydrates for the meal?

4. What is the nutrient density for protein for the meal?

5. What is the nutrient density for fat for the meal?

3. What Constitutes a Nutritious Diet?

A nutritious diet is considered to have five general characteristics:

1. Adequacy – Enough nutrients, fiber, and energy to sustain normal function.

2. Balance – Not skewed toward one nutrient or food type.

3. Calorie Control – Not less or more than required.

4. Moderation – No excess fat, salt, sugar, or other unwanted (WHAT??).

5. Variety – intake differs from one day to the next.

These five general characteristics are perhaps helpful if you already know a lot about

nutrition, but for the typical person these five characteristics do not provide enough detail

and specificity to be of much use in actually choosing specific foods. To help in

choosing specific nutrients and foods nutritionists have developed a set of “nutrient

recommendations.”

Nutrient recommendations are a set of “yardsticks”, or standards for measuring a

“healthy” person’s energy and nutrient intake. Note this idea of “nutrient

recommendations” is in economic terminology a normative concept, in the sense that it is

saying what “should” be done to obtain optimal health. The explicit goal of these

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recommendations is good health, not what necessarily taste the best, is cheapest, or is

most convenient.

Dietary reference intakes (DRIs) serve as the foundation for recommendations related

to nutrient intake. The National Academy of Sciences’ Institute of Medicine has a Food

and Nutrition Board and from that board there is a DRI committee composed of nutrition

experts that determine DRI variables and values. The Dietary Reference Intakes (DRI)

are four variables or measurements of the nutrient intakes of healthy people in the United

States and Canada. The four variables are:

1. Estimated Averages Requirements (EARS)

2. Recommended Daily Allowances (RDA)

3. Adequate Intakes (AI)

4. Tolerance Upper Intake Levels (UL)

DRIs are determined for all of the vitamins and minerals, as well as carbohydrates, fiber,

lipids, protein, water, and energy.

How are these four variables defined?

Estimated Average Requirement (EAR) – The average daily intake level for a nutrient

which meets the needs of 50 percent of the population in particular life stages and gender

groups.

Recommended Daily Allowances (RDA) – The average daily nutrient intake level that

meets the needs of nearly all (97% to 98%) of healthy people in a particular life stage and

gender group.

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Adequate Intake (AI) – The recommended average daily nutrient intake levels based on

intakes of healthy people (observed or experimentally derived) in a particular life stage

and gender group and assumed to be adequate.

Tolerable Upper Intake Levels (UL) – The highest average daily nutrient intake level

that is likely to pose no risk of toxicity to almost all healthy individuals of a particular life

stage and gender group.

The following facts help put the DRI recommendations in perspective:

• The values are based on scientific evidence to the greatest extent possible and

are periodically updated.

• Values are based on concepts of probability and risk: low probability of

deficiency and no risk of toxicity.

• Values are recommended for optimal intakes, not minimum requirements.

They include a large safety margin.

• The values are set in reference to certain indicators of nutrient adequacy, such

as blood nutrient concentrations, normal growth, and reduction of certain chronic

diseases.

• The values reflect daily intakes to be achieved over time, on average.

• Recommendations apply to a healthy person only.

All of these recommendations are based on different aspects of the empirical distribution

of nutrient intakes. To understand the differences in these measures consider a simple

example of 10 people as given in table 8.

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Table 8. Sample Daily Intake of Protein Individual Average Daily Intake (g)

1 10 2 15 3 28 4 36 5 45 6 48 7 54 8 60 9 64

10 72 The EAR for this data would be 45 g as 50% of the individuals consume this amount of

protein or less. If the RDA was defined to meet the needs of 90% of the population then

the RDA for this sample would be 64 g as 90% of the individuals consume this amount or

less. However, because the actually RDA percentage is between 97% and 98%, for this

sample the actual RDA would be somewhere between 64 g and 72 g. The AI and UL

would represent other points within this distribution of intakes. More generally we can

think of there being a distribution of average daily nutrient intakes such as,

XDRA

.02 to .03 of distribution

EAR

It is important to remember that all of these measures and recommendations are age

and gender specific, meaning there are different values for different ages and males and

females. The DRI committee publishes tables of all the DRIs and can be found online at

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the Food and Information Nutrition Center (FINC) http://www.nal.usda.gov/fnic/ and

following the link for Dietary Guidelines. Table 9 below gives an example of what can

be found there in terms of RDAs/AIs for the energy yielding macronutrients, two

vitamins and two minerals for the age range covering most in this class. Of course the

actual tables have the DRIs for all the micronutrients (i.e., 14 vitamins and 15 minerals).

Table 9. Sample of RDAs or AIsa

RDAs or AIs Male 19 - 30 y Female19 - 30 y

Carbohydrates (g/d) 130 130 Protein (g/d) 56 46 Fat (g/d) ND ND Vitamin C (mg/d) 90 75 Vitamin E (mg/d) 15 15 Calcium (mg/d) 1000 1000 Iron (mg/d) 8 18 a. RDAs in bold and AI non-bold. ND = Not determinable due to lack of data of adverse effects with lack of ability to handle excess amounts. Source: National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

While useful the DRI measures are not expressed on a normalized scale that allows

for ease in comparison of one or more nutrients and foods. One such measure is the

Acceptable Macronutrient Distribution Range (AMDR). The Acceptable

Macronutrient Distribution Range (AMDR) is a nutrient density range that is

sufficient to provide adequate total energy and nutrients while reducing the risk of

chronic disease.

With these measures, the DRI committee has four main goals:

1. Set recommended intake values – Recommended intake values are based on

either RDAs or AIs. RDA is based on experimental and reliable observations. AI

is based on some guess work. If there is insufficient evidence for a RDA, an AI is

given instead.

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2. Facilitate Nutrition Research and Policy – The EARs are used to establish

guidelines to be used in research and policy work, and form the basis of the

RDAs.

3. Establishing Safety Guidelines – The ULs provide upper limits before toxicity

is expected to occur.

4. Preventing Chronic Diseases – The following AMDR provide adequate

energy and adequate nutrients for adults 20–35 while reducing the risk of chronic

diseases:

• 45% - 65% energy from carbohydrates

• 20% - 35% energy from fat

• 10% - 35% energy from protein

B. Foods and Nutrition

Ok, so we have some good background now on nutrients but people eat foods, which

leads to a natural question

How do we calculate the amount of nutrients in a diet composed of various foods?

Don’t let the word “calculate’ scare you. The calculations are not that hard but it does

involve some math. Just read slowly. Think of it this way. Foods are bundles of

nutrients or a delivery device for nutrients. We have already seen this in the previous

section where we talked about the nutrient content of different food items. For example,

from table 3 we know that there are 47 g of carbohydrates in a Big Mac Hamburger that

weighs 216 g. This means that .218 = 47/216 of the total grams in a Big Mac Hamburger

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are associated with carbohydrates or the carbohydrate conversion factor is .218 for Big

Mac Hamburger. The carbohydrate conversion factor for Raw Carrots is .0984 = 12/122

and for a Coca-Cola is .114 = 41/360. The other nutrient conversion factors can be

similarly determined.

Let us then define the nutrient conversion factor to be the amount by which you

multiply the quantity of food to determine the amount of that nutrient. This implies that if

we know the nutrients conversion factors for the different foods in a meal then we can

calculate the total nutrient intake from those foods. For example suppose we want to

know the total amount of carbohydrates in Meal 1 (1 Big Mac, 1 c raw carrots, and 1 12

ounce Coke) and we know the conversion factors for carbohydrates are .217, .098, and

.11 for these items in the meal. The total carbohydrates for Meal 1 is then

100 = .2176×216 + .0984×122 + .114×360.

(Aside: Note this is the same as reported in table 5 as it should be. Do you know why?).

Calculating the total amount of nutrients from a collection of foods is such a critical

part of the discipline of nutrition that we need to understand the more general formula.

Let the variable F1 denote the quantity (in grams) of food item one, F2 denote the

quantity (in grams) of food item two, F3 denote the quantity (in grams) of food item

three, etc, or more generally Fi where i is just an indexing mechanism and j = 1,2,…, K

so there are K foods. Furthermore let α11 be the nutrient conversion factor for nutrient

one in food one, α12 be the nutrient conversion factor for nutrient one in food two, α13 be

the nutrient conversion factor for nutrient one in food three, etc. So the general formula

for nutrient one is then

1 11 1 12 2 1(11) . . . K KN F F Fα α α= + + +

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where N1 just stands for the quantity of nutrient one (in grams).

Huh? Don’t panic. Just keep reading slowly. Ok, so for the above example let the

first food item be the Big Mac (so F1 = 216), the second food item be the Raw Carrots (so

F2 = 122) and the Coca-Cola the third food item (so F3 = 360). Now let the first nutrient

be carbohydrates, so the corresponding nutrient conversion factors are for the Big Mac

(α11 = .2176), for the Raw Carrots (so α12 = .0984) and for the Coca-Cola the third food

item (so α13 = .114). Substituting these values into equation (11) gives the value of 100

carbohydrates for Meal 1.

Equation (11) is the formula for nutrient one, but this formula applies to other

nutrients as well by just relabeling the nutrient number. So the general formula is then

1 1 2 2(12) . . . 1,2,...,i i i iK KN F F F i Jα α α= + + + =

where there are J nutrients. Note the i subscript on the nutrient conversion factors, so the

nutrient conversion factors differ by nutrient and food item. Later we will write this

relationship between food and nutrients as Ni =N(F1, F2,…, FK), which is just a shorthand

and more general way of saying the level of a nutrient depends on or is a function of the

amount of foods consumed. This notation is known as function notation and we will

discuss it in more detail at the beginning of the economics section.

THINK BREAK!!!!!!:

Below are the nutrient conversion ratios for one slice of Meat Lovers Pizza Hand Tossed

and a 16 oz. serving of lemonade.

Table 10. Nutrient Conversion Factors Food Item  Quantity  Weight  Carb   Prot  Fat  Meat Lovers Pizza (Hand Tossed)  1 slice  125  .13  .24  .12 Lemonade  16 oz.  483  .16  .002  0 

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If these two items are consumed together….

1. How many grams of carbohydrates are there?

2. How many grams of protein are there?

3. How many grams of fat are there?

Is your head starting to hurt yet from all these calculations and symbols flying

around? If so you are not alone. Though we have just skimmed the surface of nutrients

and nutrient recommendations it should be clear that there is a major limitation associated

with basing diet recommendations on nutrient intake. Individuals do not choose and

consume nutrients. Individuals choose and consume food items. By basing nutrient

recommendations solely on nutrients the consumer implicitly must be able to translate

from the food dimension to the nutrient dimension with ease. What does this mean? Well

there are 3 energy yielding macronutrients, 14 vitamins, and over 15 minerals considered

in defining a nutritious diet. Consequently, at a minimum there are 42 equations such as

equation (12) or more succinctly J > 42. In addition, if there are about 30,000 food items

in a typical food store then the K in equation (12) is potentially extremely large and this is

not even considering the other measures such as EARs, DRAs, nutrient density, energy

density that are relevant for a healthy diet. The amount of mental capital required to keep

track of all this information much less process it is overwhelming and requires a great

deal of nutrition knowledge that most individuals do not posses.3 Basing diet

recommendations on nutrients implicitly assumes the consumer has the knowledge and

3 Research in psychology has shown that humans can process at most about three variables at a time. For example See Halford, Wilson, and Phillips “Processing capacity defined by relational complexity: Implications for comparative, developmental, and cognitive psychology.” Behavioral and Brain Sciences (1998): 21, 803-865.

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computational capacity to convert different food items in to their nutrients components

and then compare those foods based on their nutrient quality. This is a rather unrealistic

expectation. This problem is well recognized in nutrition. As Mark B. McClellan,

Commissioner of the Food and Drug Administration (FDA) in 2003, has stated

People shouldn't need a calculator or an advanced degree in math or nutrition to calculate what makes a healthy diet. So we have to find a way to make the key information we require to be placed on individual food products easier for consumers to understand and use from the standpoint of what constitutes a healthy meal and a healthy diet. Right now, we communicate some very useful information about the nutritional value of individual foods, and we provide some help in thinking about how foods can contribute to a healthy diet. But combining foods into a healthy diet is still too complicated. Instead of doing the math, consumers often do simple substitutions, such as trading off a low-calorie cola with a high-calorie dessert. We need to find better, simpler ways to help consumers understand the nutritional value of entire diets. (M. B. McClelland, Speech given at Harvard School of Public Health 2003).

Because of these computational difficulties and limitations nutrition recommendations

are usually presented in terms of foods or groups of foods.

Food Classifications and Guidelines

Food is any substance that the body can take in and assimilate that will enable it to stay

alive and grow. This definition is simple enough but not very useful because there are so

many items that satisfy this definition. Any time a definition of a group of items is very

broad it is common to further partition the groups into other categories and so it is with

food. Here are some of the most common food categories or types.

Basic Foods – Milk and milk products, meats and similar foods such as fish and poultry,

vegetables, including dried beans and peas; fruits and grains. Also called whole foods.

Enriched/Fortified Foods – Foods to which nutrients have been added.

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Fast Foods – Restaurant food that is available within minutes of ordering.

Food-at-Home – Food prepared at home.

Food-Away-From-Home – Food prepared at some other location than a home.

Functional Foods – A misleading term to define a group of foods known to possess

nutrients or non-nutrients that might lend protection against diseases.

Medical Foods – Foods specially manufactured for use by people with medical disorders

and prescribed by physicians.

Natural Foods – No legal definition, but is often used to imply wholesomeness.

Nutraceutical Foods – A term with no legal or scientific meaning that refers to foods

claimed to have medicinal effects.

Organic Foods – Foods grown without synthetic pesticides.

Partitioned Foods – Foods composed of parts of whole foods, such as butter (from

milk), sugar (from beets), or corn oil (from corn)

Pre-prepared Foods –Foods have some minimal level of processing that can be used in

combinations with other foods.

Processed Foods – Foods subject to any process, such as milling, alteration of texture,

addition of additives, cooking, or others.

Staple Food – Food used frequently or daily (e.g. rice in Asia).

Clearly these classification schemes are not mutually exclusive. Many food items

could be classified under several types. For example, the McDonald’s hamburger is fast

food, food-away-from, and is certainly a processed food. Milk is certainly a basic food,

but it is also a natural food and may also be an organic food or in some cultures a staple

food. The general point is that there are numerous ways to classify foods and different

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classification schemes will be based on some common characteristics of the foods in that

category.

C. Nutrient and Food Recommendations

In this section we discuss nutrient and food recommendations. Most of these stem from

the Dietary Guidelines for Americans (DGA).4 Every 5-years the Dietary Guidelines

Advisory Committee (DGAC), which is appointed by the Secretaries of the U.S.

Department of Health and Human Services (HHS) and the U.S. Department of

Agriculture (USDA) review the most recent scientific information on nutrition and

published what is known as the DGAC Report

(http://www.health.gov/dietaryguidelines/dga2005/ report/). The report is a scientific

analysis and is not intended for distribution to the general public. However, from this

report the HHS and USDA jointly develop the Dietary Guidelines for Americans (DGA).

The purpose of the DGA is to use the current state-of-the art knowledge on nutrients and

foods to develop recommendations for healthful eating patterns that can be adopted by

the public.

A key component of the DGA is the grouping of foods into seven groups. These

seven basic food groups are

1. Fruits

2. Vegetables 4 The description of the Dietary Guidelines For Americans 2005 draws heavily from the Executive Summary from the Dietary Guidelines For Americans 2005, which can be found at http://www.health.gov/dietaryguidelines.

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3. Grains

4. Meat, Poultry, Fish, Dried Peas and Beans, Eggs, Nuts

5. Milk, Yogurt, Cheese

6. Oils

7. Solid Fats and Added Sugars

The DGA gives a rather extensive list of the foods falling into these food groups.

These food groups play a prominent role in the recommendations and several

recommendations are stated in terms of consumption of these food groups. The key

recommendations coming from the DGA are grouped into nine inter-related focus areas.

Table 11 gives a summary of the key recommendations for the general population.

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Table 11. Key Recommendations for General Population from the Dietary Guidelines for Americans 2005.

1. ADEQUATE NUTRIENTS WITHIN CALORIE NEEDS

• Consume a variety of nutrient-dense foods and beverages within and among the basic food groups. • Choose foods that limit the intake of saturated and trans fats, cholesterol, added sugars, salt, and alcohol. • Adopt a balanced eating pattern across foods

2. FATS

• Consume less than 10 percent of calories from saturated fatty acids and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible. • Keep total fat intake between 20 to 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils. • When selecting and preparing meat, poultry, dry beans, and milk or milk products, make choices that are lean, low-fat, or fat-free. • Limit intake of fats and oils high in saturated and/or trans fatty acids, and choose

products low in such fats and oils. 3. CARBOHYDRATES

• Choose fiber-rich fruits, vegetables, and whole grains often. • Choose and prepare foods and beverages with little added sugars or caloric sweeteners, such as amounts suggested by the USDA Food Guide and the DASH Eating Plan. • Reduce the incidence of dental caries by practicing good oral hygiene and consuming sugar- and starch-containing foods and beverages less frequently.

4. SODIUM AND POTASSIUM

• Consume less than 2,300 mg (approximately 1 teaspoon of salt) of sodium per day. • Choose and prepare foods with little salt. At the same time, consume potassium-rich foods, such as fruits and vegetables.

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Table 11. Con’t 5. FOOD GROUPS TO ENCOURAGE

• Consume a sufficient amount of fruits and vegetables while staying within energy needs. Two cups of fruit and 2½ cups of vegetables per day are recommended for a reference 2,000-calorie intake, with higher or lower amounts depending on the calorie level. • Choose a variety of fruits and vegetables each day. In particular, select from all five vegetable subgroups (dark green, orange, legumes, starchy vegetables, and other vegetables) several times a week. • Consume 3 or more ounce-equivalents of whole-grain products per day, with the rest of the recommended grains coming from enriched or whole-grain products. In general, at least half the grains should come from whole grains. • Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products.

6. WEIGHT MANAGEMENT

• Balance calories from foods and beverages with calories expended. • To prevent gradual weight gain over time, make small decreases in food and beverage calories and increase physical activity.

7. PHYSICAL ACTIVITY

• Engage in regular physical activity and reduce sedentary activities. • To reduce the risk of chronic disease in adulthood: Engage in at least 30 minutes

of moderate-intensity physical activity, above usual activity most days of the week.

• To help manage body weight in adulthood: Engage in approximately 60 minutes of moderate- to vigorous- intensity activity on most days of the week while not exceeding caloric intake requirements. • To sustain weight loss in adulthood: Participate in at least 60 to 90 minutes of

daily moderate-intensity physical activity while not exceeding caloric intake requirements. Some people may need to consult with a healthcare provider before participating in this level of activity.

• Achieve physical fitness by including cardiovascular conditioning, stretching exercises for flexibility, and resistance exercises or calisthenics for muscle strength and endurance.

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Table 11. Con’t 8. ALCOHOLIC BEVERAGES

• Those who choose to drink alcoholic beverages should do so sensibly and in moderation—defined as the consumption of up to one drink per day for women and up to two drinks per day for men. • Alcoholic beverages should not be consumed by some individuals, including those who cannot restrict their alcohol intake, women of childbearing age who may become pregnant, pregnant and lactating women, children and adolescents, individuals taking medications that can interact with alcohol, and those with specific medical conditions. • Alcoholic beverages should be avoided by individuals engaging in activities that require attention, skill, or coordination, such as driving or operating machinery.

9. FOOD SAFETY

• To avoid microbial food borne illness: Clean hands, food contact surfaces, and fruits and vegetables. Meat and poultry should not be washed or rinsed. • Separate raw, cooked, and ready-to-eat foods while shopping, preparing, or

storing foods. • Cook foods to a safe temperature to kill microorganisms. • Chill (refrigerate) perishable food promptly and defrost foods properly. • Avoid raw (unpasteurized) milk or any products made from unpasteurized milk,

raw or partially cooked eggs or foods containing raw eggs, raw or undercooked meat and poultry, unpasteurized juices, and raw sprouts.

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The numbering in table 11 does not indicate any type of priority ordering and all nine

recommendations are equally important. It also should be recognized that this is just a

summary of the key recommendations as the DGA has a full chapter devoted to each one

of these nine focus areas, so there is a lot more detail in each focus area.

So What Does the DGA Mean for a Diet?

While the DGA is certainly a step in the right direction in terms of translating nutrient

recommendations into food recommendations, it is still “informationally dense” and not

in a ‘digestible’ form to the consumer. Diet planning is designed to connect the

recommendations from nutrition science with the food people consume and this involves

several educational tools. One such tool is the food group plan. The food group plan is

a diet planning tool provided by USDA that sorts foods into groups based on their

nutrient content and then specifies that people should eat a certain minimum number of

servings for foods from each group. The USDA food group plan is known as the USDA

Food Guide and table 12 gives a sample from that table.

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Table 12. Sample USDA Food Guide Table Daily/Weekly Servingsa

Food Group Calories 1600 2000 2400

Fruits 1.5 c (4 srv) 2 c (4 srv) 2 c (4 srv) Vegetables 2 c (4 srv) 2.5 c (5 srv) 3 c (6 srv) Dark Green 2 c/wk 3 c/wk 3 c/wk Orange 1.5 c/wk 2 c/wk 2 c/wk Legumes 2.5 c/wk 3 c/wk 3 c/wk Starchy 2.5 c/wk 3 c/wk 6 c/wk Other 5.5 c/wk 6.5 c/wk 7 c/wk Grains 5 oz-eq 6 oz-eq 8 oz-eq Whole 3 3 4 Other 2 3 4 Lean Meat and Beans 5 oz-eq 5.5 oz-eq 6.5 oz-eq Milk 3 c 3 c 3 c Oils 22 g 27 g 31 g Discretionary Calorie Allowance 182 267 362 a Taken from the USDA Dietary Guidelines for Americans 2005. The DGA provides a rather extensive list of the sub-food types (e.g., Dark Green vegetables) from which a consumer can choose.

The calorie columns indicate the amount of calories consumed. So for example if the

recommended energy intake for someone is 2000 calories per day then if they consume

about 2 c of fruits, 2.5 c of vegetables, 6 ounces of grain, 5.5 ounces of lean meat or

beans, 3 c of milk (products), and 27 g of oil products per day then they will generally

meet the nutritional recommendations in terms of nutrients. One should realize that there

is still a great deal of substitutability within these food groups and this guide is not as

rigid as it may seem at first. Note at the bottom of this table is a row called Discretionary

Calorie Allowance. The Discretionary Calorie Allowance (DCA) is the balance of

calories remaining in a person’s energy allowance after accounting for the number of

calories needed to meet recommended nutrient intakes through consumption of nutrient

dense food. Simply stated, after you consume the amounts given in the table, the DCA

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indicates how much you have to play with. Alternatively, the caloric value of all the

items in the portions given must be for the 2000 calorie diet 1733 = 2000 – 267.

Though the Food Guide is certainly more user friendly than recommendations

expressed in terms of nutrients, USDA has developed the MyPyramid as an educational

tool to make implementing the Food Guide even easier.

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MyPyramid

MyPyramid is an educational tool developed by the USDA to help individuals follow the

Food Guide. The general idea behind MyPyramid is to give a quick, visual

representation of what foods should be consumed. Figure 1 below shows the MyPyramid

diagram.

Figure 1. MyPyramid.

The design of the MyPyramid is intended to reflect the major components of the Food

Guide. The six different colors represent the different food groups. Proportionality of

these food groups is represented by the width of each color band, so for example grains,

vegetables and fruits should constitute over half of the diet. Because all food groups are

included variety is captured as well. The steps are designed to reflect the importance of

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activity. Moderation is supposedly reflected by the narrowing of each food group from

top to bottom. The wider base stands for foods with little or no solid fats or added sugars.

The MyPyramid is actually a group of 12 different MyPyramids that are tailored to

specific energy requirements and activity levels.

There are numerous resources available to consumers related to the MyPyramid

concept that are targeted at different media outlets, including public service

announcements, podcasts, posters, internet video clips, and WebPages. The webpage

www.mypyramid.gov has numerous links that are based on the MyPyramid concept that

provide information and other tools for helping the consumer follow the Food Guide. For

example, the link, MyPyramid Menu Planner,

(http://www.mypyramidtracker.gov/planner/launchPage.aspx)

allows one to enter personal information related to weight and height and activity level

and then enter different food choices and see how those choices compare to the Food

Guide recommendations. Alternatively one can use the MyPyramid Tracker

(http://www.mypyramidtracker.gov) to assess dietary and physical activity. For example,

there is a Food Calories/Energy balance feature that will calculate your energy balance by

subtracting the energy you expend from physical activity from your food caloric intake.

While the MyPyramid is a useful tool, the mere fact that it condenses a great deal of

information into a simple pyramid it may come as no surprise that it has some limitations.

Here are some of the main ones as pointed out by Marion Nestle in Food Politics:

Does not distinguish the health impact of total fat from the effects of

saturated, monosaturated, polyunsaturated, and trans-saturated fatty acids.

Does not emphasize the fact that there are no “good” or “bad” foods.

35

Does not emphasize whole, minimally processed grains compared to refined

grains.

Does not separate beans (a vegetable) from meat.

Does not distinguish high-fat from low-fat meat and dairy products.

Does not guide educators and the public in placing commonly consumed

foods in appropriate groups.

Does not explain serving sizes adequately or consistently.

Convey the complexities of information about nutrition and health.

Does not distinguish serving recommendations that should be considered

upper limits (meat and high-fat dairy foods) from those that should be considered

lower limits (grain, fruit, and vegetable soups).

Though these are obvious limitations of the MYPyramid as it stands, there are two

other perhaps more important limitations. First, the MyPyramid only applies to food

groups. However, much food that is purchased is processed to some degree and does not

really fit into a food group. For example, what food group does a can of Campbell’s

Mushroom soup fall in to? Or even more processed, a Healthy Choice Zucchini

Lasagna? Second, and related to one, MyPyramid is a good general planning and

evaluation tool over several days, but it is not very useful when a consumer is standing in

the store trying to compare two different food items (e.g., Count Chocula versus Honey

Gone Nuts Granola). To address these problems requires that individual food items have

nutritional information on the label.

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Food Labels: Required Items Prior to 1990, there was no uniform standard for the type of information that could be

placed on a food label. Consequently, and as part of marketing efforts, many companies

made claims about their foods that were at a minimum misleading and in some cases just

false. The Nutrition Education and Labeling Act (NELA) of 1990 was passed in order to

address this problem. The NELA requires every food packaged to contain the following

information:

1. The common or usual name of the product.

2. The name and address of the manufacturer, packer, or distributor.

3. The net content in terms of weight, measure, or count.

4. Nutrient contents of the product (nutrition facts panel).

5. The ingredients in descending order of predominance by weight.

The actual content of the label will depend on the size of the product. For example a

cereal box might include all nutrients including vitamins and mineral, whereas a can of

tuna may contain an abbreviated listing of nutrients. A candy bar label may just have a

phone number for providing the information. Figure 2 shows a nutrition label for a box

of cookies.

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Figure 2. Cookies Food Label Example

Starting at the top of the label, the serving size is expressed in some common units, such

as number of cookies, but also in grams and then the servings per container. The

following information is all expressed in terms of nutrient content per serving. Total

calories (160) are given along with total calories from fat (60). The major macro and

micronutrients in the product are then listed in terms of grams and daily values. The

Daily Values (DVs) are daily nutrient standards expressed as a percent of a 2,000 calorie

diet. For this box of cookies total fat is 7.0g and this constitutes 10% of what the total

38

amount of fat recommended for a daily caloric intake of 2000 calories. Total fat is

further broken down into saturated fat and trans fat. Cholesterol and sodium measures

are also given. Total fat, Cholesterol, and sodium should be consumed in limited

quantities and kept at a minimum. The general rule of thumb or quick guide is to look for

items where these DVs are 5% or less and 20% or more is considered high. The other

two energy yielding macro nutrients are given as well (Total carbohydrates and Protein).

The next section gives the key vitamins and minerals in the food item. In terms of a

quick guide, dietary fiber, Vitamin A, Vitamin C, Calcium, and Iron should have daily

values 20% or more. The bottom panel, or footnote, indicates that DVs are based on a

2000 calories per day diet. This footnote is the same for all food products. For some

products there will be additional information given in the footnote. This information lists

the guidelines or recommendations for the relevant nutrients for different caloric intake

levels. Note these numbers give the maximum amount that should be consumed of these

nutrients for this caloric intake for a given day across all foods. This is not the amount

that can be consumed from just this item, unless this is the only item you consume all

day. The DVs are actually calculated using these numbers along with the quantity of the

nutrients per serving given above. For example, the DV for Total Fat is

. The other DVs are calculated similarly or the general formula

for a nutrient DV is

10% (7 / 65 ) 100g g= ×

(13) 100ii

i

NDVRN

⎛ ⎞= ×⎜ ⎟⎝ ⎠

where Ni is as before, the nutrient quantity of nutrient i and RNi is the recommended

nutrient intake for nutrient i. Finally, below the Nutrition Facts panel are given the

ingredients in the item in descending order of weight contribution. For example, for

39

these cookies the ingredient list indicates that the largest portion of the weight is sugar,

followed by enriched wheat flower, then vegetable shortening, etc…

There are several points to keep in mind when considering the information on nutrient

levels:

There are going to be tradeoffs or substitutions to consider between the

different nutrients. For example, the quick guide indicates that these cookies are

high in fat (DVfat = 10%) but nonexistent in terms of Vitamin A (e.g., DVVitA =

0%).

All nutrient content information is based on a single serving but most

containers will have more than one serving. Consequently, the actual nutrient

intake and DVs will equal the number of servings consumed. For example, if the

container has two servings and you consume two servings then all values in the

nutrient label will be doubled.

Two similar products may contain different calorie levels making it difficult

to compare the nutrient content of one to the other without converting them to a

common serving size.

Not all nutrients will have both the quantity and DVs given on the label. This

is because the DRI committee could not form a conclusive opinion on the

numbers.

Food Labels: Optional Items The above food label information is required on all food items, but there are additional

optional items mainly related to additional nutrient claims and health claims. The

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Nutrient Claims are claims about nutrients that must meet some specified criteria.

These claims are broken down mainly in terms of calories and fat related items. Table 13

gives the criteria for different nutrient claims.

Table 13. Nutrient Claims and Their Meaning ENERGY TERMS (PER SERVING)

Low calorie - ≤ 40 calories

Reduced calorie - at least 25% lower in calories than a regular or reference food.

Calorie free - < 5 calories

FAT TERMS (MEAT AND POULTRY PRODUCTS)

Extra Lean (per serving) < 5 g fat + < 2 g (saturated and trans fat) + < 95 mg cholesterol

Lean (per serving) < 10 g fat + < 4.5 g (saturated and trans fat) + < 95 mg cholesterol

FAT TERMS (MAIN DISHES AND PREPARED MEALS)

Extra Lean (per serving) < 5 g fat + < 2 g (saturated and trans fat) + < 95 mg cholesterol

Lean (per serving) < 8 g fat + < 3.5 g (saturated and trans fat) + < 80 mg cholesterol

FAT AND CHOLESTEROL TERMS (ALL PRODUCTS)

Cholesterol Free (per serving) < 2 mg cholesterol + ≤ 2 g (saturated and trans fat)

Fat Free (per serving) < .5 g fat

Less Saturated Free (per serving)

at least 25% lower in calories than a regular or reference food.

Low Cholesterol (per serving) ≤ 20 mg + ≤ 2 g fat

Low fat (per serving) < 3 g fat

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Low saturated fat (per serving) ≤ 1 g saturated fat + < 0.5 g trans fat

Reduced or less cholesterol (per serving) ≥ 25% less cholesterol compared to reference food + ≤ 2 g saturated fat

Reduced Saturated Fat (per serving) ≥ 25% less saturated fat + reduced by more than 1 g saturated fat compared to reference food

Saturated Fat Free (per serving) < 0.5 g of trans fat+ < 0.5 g saturated fat

FIBER TERMS

High Fiber (per serving) > 5 g fiber + must satisfy the low fat definition or level of total fat must appear next to high fiber claim

Good Source of Fiber (per serving) 2.5 g to 4.9 g of fiber

More or Added Fiber (per serving) ≥ 2.5 g serving relative to reference food

SODIUM TERMS

Low Sodium (per serving) ≤ 140 mg

Reduced Sodium (per serving) ≥ 25% less sodium than reference food

Sodium Free (per serving) < 5 mg

Very Low Sodium (per serving) ≤ 35 mg

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OTHER TERMS

Free, Without, No, Zero (per serving) Zero or trivial amount

Calorie Free (per serving) < 5 calories

Sugar or Fat Free (per serving)

< .5 g

Fresh Raw, unprocessed, or minimally processed

Good Source (per serving) 10% to 19% of Daily Values

Healthy Low in fat, saturated fat, trans fat, cholesterol, and sodium and containing at least 10% of Daily Values for vitamin A, vitamin C, iron, calcium, protein, or fiber.

High In (per serving) 20% or more of Daily Values

Less, Fewer, Reduced ≥ 25% less of a nutrient or calories than reference food

More, Extra (per serving) ≥ 10% more than Daily Values in reference food

Light (per serving) - three possible meanings

1. 1/3 fewer calories or half the fat of the regular product 2. 1/2 sodium normally present 3. Light in color or texture.

These nutrient claims are designed to help “simplify” the nutrient information. Do you

think they do that?

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Health Claims are claims linking certain nutrients to health claims and must satisfy

criteria set by the FDA. Examples of health claims are statements such as “calcium and

reduced risk of osteoporosis” or “dietary fat and reduced risk of cancer.” The FDA has

four levels on their ‘report card’ health claims.

A – High level of confidence in health claim with significant scientific

agreement. No disclaimers.

B – Moderate level of confidence in health claims with supportive but not

conclusive evidence.

C – Low level of confidence in health claim with limited evidence that is not

conclusive.

D – Extremely Low level of confidence in health claim with little scientific

evidence supporting the claim.

While nutrient claims are rather precisely defined, health claims are much more tenuous

because the relationship between nutrition and health is obviously much more tenuous as

we will discuss in the next section.

D. Diet and Health

So far we have covered the relationship between nutrients and foods, and nutrition

recommendations and guidelines. Much of the motivation for developing nutrition or

diet guidelines is to reduce the onset of several chronic diseases. Indeed, as was

indicated in module I, four of the top 10 leading causes of death (e.g., heart disease,

cancer, strokes, and diabetes) are all known to be highly correlated with diet. It is

important to note that correlation is not causation. What we mean by correlation in this

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context is that while diet is one factor that can influence the onset of a disease, there are

certainly other factors as well. For example, other factors that may affect the onset of a

disease would be genetics, exercise, smoking, or environmental conditions such as

pollution or sanitation practices. These other factors can either attenuate or accentuate

the effects of a specific diet. For example, we all probably know a friend who seems to

be able to eat as much of anything they want and they seem to never gain any weight.

This person probably has a unique genetic makeup that tends to offset the negative

impacts of a poor high caloric diet. Alternatively, it is well established that a diet high in

fat may accentuate the chance of heart disease but a consistent vigorous exercise program

would tend to attenuate the effects of the high fat diet on the chance of developing heart

disease. The general point is that when we talk about the connection between diet and

health there is an implicit assumption that we are holding all other variables constant or

equal. This type of “holding all else constant or equal” reasoning is pervasive in science

and usually goes by the Latin name ceteris paribus, which means other things being

equal. So when someone says that a high fat diet increases the likelihood of heart disease

they are implicitly saying, more accurately, that a high fat diet increases the likelihood of

heart disease, ceteris paribus. While more technically correct, adding the ceteris paribus

phrase to every diet health claim becomes extremely repetitive and retentive and is

therefore often usually not included.

Because the relationship between diet and disease (or more generally health) is not

one-to-one, nutritionists and health professional usually refer to the different factors that

can affect the onset and level of a disease as risk factors. Risk factors are factors known

to be related to (or correlated with) diseases but not proven to be causal. To make sure

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we are on the same page we should probably define risk as well. If one goes to a

dictionary and looks up the word risk they will find something like, risk is exposure to

the chance of injury or loss. This is not the definition of risk we will use because it does

not distinguish between measureable risk and unmeasurable risk. There are chances of

loss that can be measured and there are chances of loss that we have no idea of how to

measure. For example, suppose we bet a dollar on a coin toss. You win if it turns up

heads and I win if it turns up tails. Assuming the coin is fair, we know you have a 50%

chance of loss or your risk of loss is 50%. Now contrast this with a dollar bet on Virginia

Tech changing its primary colors to orange and black within the next 5 years. There is

certainly a chance this could happen but there is no precedent or data for assigning a

number to this chance as in the coin toss case. To distinguish these two cases we will

reserve the term risk for cases where there is a quantifiable chance or probability of loss.

We will refer to a chance that is non-quantifiable as referring to uncertainty.5

The table 14 below list the major diet related risk factors for several chronic diseases.

As the table shows, several of the same dietary intake patterns are associated with

increasing the probability of several chronic diseases. For example, a diet high in fat,

saturated fat, and trans fats increases the probability of having all four of these chronic

diseases.

5 This important distinction between risk and uncertainty is based on the distinction made by Economist Frank Knight in his 1921 publication Risk, Uncertainty, and Profit. This distinction is to some extent one of available data and knowledge and will become more important in the economics section.

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Table 14. Diet Related Risk Factors with Some Chronic Diseases Chronic Diseases Risk Factors Atherosclerosis Hypertension Strokes Cancers Diet high in fat, saturated fat and trans fat

Low complex carbohydrate intake

High intake of salty or pickled foods

Low vitamin and mineral intake

Excessive alcohol intake Source: Sizer and Whitney Chpt. 11.

So how does diet affect the probability of these chronic diseases? That is, what are the

mechanisms through which the diet works to increase the probability of these diseases?

A complete answer to this question is beyond the scope of this review but it is important

to understand the processes at some rather basic level. Here we will just cover the

relationship between diet and the cardiovascular diseases and diet and cancer. The

connection between diet and cardiovascular disease is much better understood than the

relationship between diet and cancers.

Diet and Cardiovascular Disease About 80 million people in the US suffer from some form of cardiovascular disease

(CVD). The common form of CVD is atherosclerosis. Atherosclerosis is the condition

of plaques forming on the artery walls. The common name of atherosclerosis is

“hardening of the arteries.” Everyone will have various degrees of atherosclerosis, the

issues is how to reduce it. Figure 3 gives an overview of the sequence of progression of

atherosclerosis.

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Figure 3. Progression of Atherosclerosis (Source??WEB)

Atherosclerosis usually begins with the accumulation of soft, fatty streaks along the inner

walls of the arteries, especially at branch points. These gradually enlarge and become

hardened fibrous plaques that damage artery walls. Plaques are mounds of lipid material

mixed with smooth muscle cells and calcium that develop in the artery walls. A diet high

in saturated fat is a major contributor to the development of plaques and the progression

of atherosclerosis. However, atherosclerosis is a much more complex process than just

an accumulation of lipid material on the cell walls. Atherosclerosis is a complex

response of the artery to tissue damage and inflammation.

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Inflammation is part of the body’s immune defense against injury, infection, or

allergens and is marked by increased blood flow, release of chemical toxins, and the

attraction of white blood cells to the infected area. The damage may begin from a

number of factors interacting with cells that line the arteries but the two most important

are High LDL cholesterol and Hypertension.

High LDL Cholesterol and Artery Integrity  Cholesterol is a member of the group of lipids known as sterols and is a soft, waxy

substance made in the body for a variety of purposes. LDL is the acronym for low-

density lipoproteins. Lipoproteins are clusters of lipids associated with proteins, which

serve as the transport vehicle for lipids in the blood and lymph system. Consequently,

low-density lipoproteins (LDL) denotes one of the major classes of lipoproteins and

they carry cholesterol to the cells, including those lining the arteries. They are the

lipoproteins most likely to produce plaques in arteries (i.e., they are atherogenic). On the

other hand, high-density lipoproteins (HDL) denotes the other main class of

lipoproteins but they carry cholesterol away from the cells to the liver for recycling to

other uses or for disposal. LDL cholesterol and HDL cholesterol are strongly linked to a

person’s risk of developing atherosclerosis and heart disease. The higher the LDL, the

higher the risk of atherosclerosis and heart disease. The lower the HDL, the higher the

risk atherosclerosis and heart disease.

The basic process is that when cells lining arteries are damaged inflammation is

triggered which signals to the immune system to send white blood cells to the site to try

to repair the damage. Soon, particles of LDL cholesterol become trapped in the blood

vessel walls and become oxidized. The white blood cells – macrophages – flood the

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scene to scavenge and remove the oxidized LDL, but to no avail. As the macrophages

become engorged with oxidized LDL, they become foam cells, which themselves become

triggers of oxidation and inflammation that attract more immune scavengers to the scene.

Muscle cells of the arterial wall proliferate in an attempt to heal the damage, but they mix

with foam cells to form hardened areas of plaque. This cycle repeats until the inner

artery walls become virtually covered with disfiguring plaques. The buildup of plaques

in turn affects blood pressure and blood clot formation.

Normally, arteries expand with each heartbeat to accommodate the pulses of blood

that flow through them. Arteries hardened and narrowed by plaques cannot expand, so

blood pressure rises. High blood pressure is also known as hypertension. The increased

blood pressure damages the artery walls further and strains the heart. As pressure builds

up in the artery, the arterial wall may become weakened and balloon out. This ballooning

out is called an aneurism. If an aneurysm burst, especially one in the aorta, the

individual will bleed to death. In addition, abnormal blood clotting also threatens life.

Atherosclerosis, arterial damage, plaques in the arteries, and inflammation all favor the

formation of blood clots. In atherosclerosis, a sudden spasm of the artery wall or surging

in blood pressure can tear away part of the fibrous coat covering a plaque, causing it to

rupture. When a plaque ruptures, the body responds to the damage as an injury – by

clotting the blood. A stationary blood clot is called a thrombus. A thrombus that has

grown enough to close off a blood vessel is called a thrombosis. A thrombosis closing

off vessels that feed the heart muscle is called a coronary. A thrombosis closing off

vessels that feed the brain is called a cerebral thrombosis. Sometimes a thrombus

breaks loose and travels through the blood vessels. This is called an embolus and

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embolus that causes sudden closure of a blood vessel is called an embolism. Heart

attacks and strokes can be caused by either a thrombosis or an embolism.

A diet high in saturated fat and trans fatty acids contributes to high blood LDL

cholesterol. Conversely, reducing those fats in the diet lowers blood LDL cholesterol and

may reduce the risk of CVD. So the logic chain between diet and CVD is

↓ Saturated fat and trans fat ⇒ ↓ LDL cholesterol ⇒ ↓ CVD.

Diet and Cancer

Cancer is a disease where cells multiply abnormally and excessively disrupting normal

functioning of one or more organs. The actual mechanism relating diet to cancer is not as

well understood as in the case of CVD. Cancer ranks second only to heart disease as the

leading cause of death and disability in the United States. For some groups, such as

women age 40 to 79 and men 60 to 79 years, cancer is the leading cause of death. One of

the most challenging aspects of making the connection between diet and cancer is that

there are many different types of cancer and cancer can be located in a wide variety of

locations in the body. An estimated 20 to 50 percent of cancers are influenced by diet

and these relationships are the focus of this section.

Foods play three roles in cancer:

1. Certain foods and their components may cause cancer.

2. Certain foods and their components may promote cancer.

3. Certain foods and their components may protect against cancer.

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As we see here the term may indicates that there are several other risk factors that can

affect the cause, promotion, and protection against cancer. So again, as discussed, when

we talk about the effects of diet we are really making a ceteris paribus statement.

Table 15 list some of the majors types of cancers, the main risk factors, and possible

protective dietary factors.

Table 15. Examples of Cancers and Diet Connections Type of Cancer Intake Association Possible Protective Effect Breast High calories; low

vitamin A; probably high saturated fat and meat; possibly high sucrose

Monosaturated fats; vegetables and fruits; calcium and vitamin D

Cervical Folate Deficiency Adequate folate intake; possibly, fruits and vegetables

Kidney Possibly, high red meat Fruits and vegetable, especially orange-colored and dark green

Liver High iron Vegetables, especially yellow and green

Lung Low vitamin A Fruits and Vegetables Ovarian Possibly, high lactose Vegetables, especially green

leafy Pancreatic Possibly, high red meat Possibly, fruits and vegetables,

especially yellow and green Prostate High in fats, especially

saturated fats and possibly milk products

Possibly cooked tomatoes, soybeans, soy products, flaxseed

Stomach High salt, refined flour starch

Fresh fruits and vegetables, especially tomatoes; possibly foods high in vitamin A and beta-carotene

Source: Sizer and Whitney Chpt. 11.

There are two general points that emerge from table 15. First, there is a heavy dose of

uncertainty and qualification with the term “possibly” repeated several places. Second,

the common theme is that an increased consumption of fruits and vegetables may have a

protective effect.

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E. A Foreshadowing Conclusion

In this module we have taken a whirlwind review of basic nutrition. The focus has been

on the technical relationships between food and nutrients and the dietary

recommendations in terms of nutrients, foods, and health. This emphasis has been

purposeful with a look ahead toward the economics section. A key requirement for

making an optimal economic decision is the presence of accurate, clear, and full

information – what an economist would call complete information. Economic decision

can be difficult enough when there is complete information but they become much more

difficult when there is incomplete information (i.e., when the information is either

inaccurate, unclear, or not easily available or processed). As this brief review has

hopefully made clear, the study of nutrition, food, and health is “informationally dense”

in that there is a lot of information that must be processed in order to understand even the

basics of the connection between nutrition, foods, and health. This is perhaps not

surprising as it is a discipline in its own right but as will become evident in the next

module, nutrition information is just one type of information the consumer must take into

account when making food, nutrient, and ultimately health choices.