Food Sciences and Nutrition 112

Principals of Human Nutrition

Food and Nutrition: An Introduction

From birth to death food is a dominant factor in our life. Besides providing

the energy for breathing at night and full activity during daytime, food builds,

maintains, and regulates muscles and bones, nerves and brain, eyes, hair, and all

our physical being. Food is also used as a link in our friendship, and as a symbol

of our religious life. Through the ages, people have learned that some foods are

more nourishing than others. The science of nutrition, on the other hand, was

grown only after the development of the sciences of chemistry and physiology and

had its beginning in the late eighteen century. Thereafter, since 1900, the

functions of the nutrients in the body, the nutritive values of foods, the body

requirements for nutrients, and the role of nutrition in health and disease were

studied. It should be emphasized that much still remains to be learned.

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Commonly used terms in nutrition

Nutrition : The sum of processes involved in taking in food and using them for

growth, development, and the maintenance of health. It includes eating the correct

kind and amount of food, digestion, and absorption of the nutrients for the

maintenance of body tissue, production of energy, and elimination of wastes.

Nutritional science: The body of knowledge developed through controlled

research that relates to the process involved in nutrition. It includes managing

food requirements of humans for maintenance, growth, activity, reproduction, and

lactation.

Nutrients: Any chemical substance found in food that is used to promote body

functions. They are divided into six basic groups: carbohydrates, fats, proteins,

vitamins, minerals, and water.

Nutrient requirement: A Specific amount of a specific nutrient needed by the

body at a certain age.

Essential Nutrients: Nutrients that are necessary for life and can’t be synthesized

by the body and therefore, must be included in the diet.

Food: Any substance, usually of plant or animal origin, when eaten, digested, and

absorbed provides one or more of the nutrients.

Diet: Includes the kinds and amounts of food and drink consumed each day. It

includes both the normal and the therapeutic diet.

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Balanced Diet: A diet that provides all the essential nutrients in appropriate

amounts.

Nutritional Status: The physical condition of the individuals that can be

determined by their diet.

Nutritional Assessment: The measurement of nutritional status based on

anthropometric and biochemical data and dietary history.

Health: The state of complete physical, mental, and social well-being and not

merely the absence of disease.

Malnutrition: Any disorder concerning nutrition. It may result from an

unbalanced, insufficient, or excessive diet. It includes:

Overnutrition: The condition that results from excessive caloric intake

and/or one or more nutrients.

Undernutrition: The condition that results from an insufficient caloric

intake and/or one or more nutrient.

Recommended Dietary Allowance (RDA): The average daily nutrient intake

level that is sufficient to meet the nutrient requirements of nearly all (97-98%)

healthy individuals in a particular life stage and gender group.

Energy: The capacity to do work. Food provides the body with energy or fuel it

needs to stay alive, move, and grow. The chemical energy found in food and used

by the body is measured in kilocalorie (Kcal) or calorie (cal).

Energy Yielding Nutrients: Nutrients that the body can use for energy

production (carbohydrate, fat, and protein).

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Calories: Units of energy. It is the amount of heat required to raise the

temperature of a kilogram of water one-degree Celsius.

Metabolism: The sum of all chemical changes that take place in the body by

which it maintains itself and produces energy for its functioning. Metabolism is of

two types:

Anabolism: The synthesis of complex molecules from simpler ones. The

reaction is energy dependent (e.g: growth).

Catabolism: The break down of complex molecules to simpler ones,

which leads to the release of energy (e.g: starvation, illness).

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Tools for Choosing a Healthy Diet

Understanding Food Labels

Ingredient List: The ingredient list includes all of the substances added

when preparing a food, including food additives, colors, and flavoring. The

ingredients are listed in order of their prominence by weight.

Nutrition Facts: Lists the serving size of the food followed by the total

calories, calories from fat, total fat, saturated fat, cholesterol, sodium, total

carbohydrate, dietary fiber, sugars, and protein per serving of the food.

Illustration:

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The Food Guide pyramid: In June 2011, MyPlate replaced MyPyramid.

A website — ChooseMyPlate.gov — which contains resources and tools

for more specific information about what and how much to eat.

On this website, consumers will find specific recommendations for each

USDA Food Group, based on the 2010 Dietary Guidelines for Americans

(DGA), including proportions based on research that relate to individual

calorie and nutrient needs.

The new MyPlate icon is a plate split into four sections, each representing a

different type of food (protein, whole grains, fruits and vegetables). The sections

vary in size depending on the recommended portion of each food a person should

eat. A circle shape next to the plate represents dairy products, especially milk.

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Viewing the icon online allows consumers to click on each section of the plate

for more information.

Functions of Foods

Food is any material, solid or liquid, which after ingestion, digestion and

absorption is used to build and maintain body tissues, regulate body processes and

supply energy.

Foods provide:

Water (environment in which cells live)

Fuel for energy (so that cells can do their work)

Building blocks (nutrients that cells use to build and repair themselves)

Metabolic regulators (nutrients that cells use to coordinate life’s processes)

The six essential nutrients and their functions

Carbohydrates Provide energy and heat

Fats Provide energy and heat

Proteins Build and repair body tissue

Provide energy and heat

Vitamins Regulate body functions

Minerals Regulate body functions

Water Regulate body functions

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1. Energy and Heat:

Dietary carbohydrates: starches and sugars are body’s primary source of fuel for

heat and energy. They also maintain the body store of quick energy as glycogen.

Each gram of carbohydrates yields 4 calories. Carbohydrates should provide 50-

66% of the total calories.

Dietary fats: provide the body with heat and energy. It is the most concentrated

form of energy yielding 9 calories/gm. Fats should provide no more than 25-30%

of the total calories, with at least 50% of this amount being unsaturated fats from

plant sources.

Dietary proteins: the body may use dietary or tissue proteins to obtain energy

when the supply of fuel from carbohydrates and fats is not enough. The fuel factor

for protein is 4 calories. Protein should provide 15-20% of the total calories.

2. Tissue building:

Proteins: primary function is tissue building. Dietary protein provides amino

acids, the building units necessary for constructing and repairing body tissues.

This is a constant process that ensures growth and maintenance of a strong body

structure as well as vital substances for the tissue function.

Minerals: such as calcium and phosphorus, which build and maintain bone tissue.

Iron is part of Hemoglobin.

Vitamins: Vitamin C is involved in developing the cementing intercellular ground

substance. The substance helps build strong tissue and prevents tissue bleeding.

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Fat: Fatty acids help build the central fat substance of cell walls, which promotes

transport of fat-soluble material across the cell wall.

3. Regulation and control:

All the chemical processes in the body needed for providing energy and building

tissue are regulated and controlled to maintain a smooth, balanced operation.

Nutrients that help regulate body processes are:

Vitamins: many vitamins function as coenzyme factors. They are components of

cell enzymes that control chemical reactions in cell metabolism (for example most

of the b-complex vitamins). Almost every action in the body requires the

assistance of vitamins.

Minerals: many minerals serve as coenzyme factors such as cobalt, which is a

central constituent of B12 vitamin (antipernicious anemia vitamin).

Water and fibers: function as regulatory agents. Water is the fundamental agent

for life, providing the essential case for all the metabolic processes. Fibers help in

regulating the passage of food materials through the gastrointestinal tract and

influence the absorption of various nutrients.

Balanced Diet:

1. Adequate (provides enough of each essential nutrient, fiber and energy).

2. Balanced (does not over emphasize one food type or nutrient at the expense of

another).

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3. Caloric controlled (provides the desired energy for the body).

4. Moderate (does not provide excess intakes of fat, salt, sugar).

5. Variety (different foods to provide different nutrients).

6. Energy intake balanced with energy expenditure (calories in = calories out).

Digestion, absorption and metabolism

Digestion:

The process whereby food is broken down into smaller parts (absorbable

units), chemically changed, and moved through the gastrointestinal (GI)

system. The process of digestion begins in the mouth.

Digestive system: All body structures that participate in digestion.

Digestion is of two parts:

1. Mechanical (teeth: crush large pieces of food into smaller ones; peristalsis: wavelike muscular contractions of the GI tract that push its contents along)

2. Chemical (hydrolysis: addition of water to break a molecule into smaller pieces; digestive enzymes: proteins that act on food substances, causing them to break down into simpler compounds)

Digestion in the mouth:

Chewing food and mixing with saliva (salivary amylase), initiates the

digestion of carbohydrates.

Salivary amylase acts on starch (very little is changed)

Digestion in the stomach:

Gravity and peristalsis transfer food down the tract.

Stomach mixes food with gastric juices.

Gastric juices:

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Pepsin → Protein

Rennin → Proteins in milk

Gastric Lipase → Emulsify fat

Gastric juices contain HCL

Functions of HCL:

- Break down food to make them easily attacked by the enzymes.

- Provides the acid medium necessary for the action of pepsin.

- Increases the solubility of calcium and iron salts to enhance their

absorption.

- Destroys bacteria present in food.

Mucus, a thick, slippery, white substance that coats the stomach’s cells, is

secreted by the goblet cells of the stomach wall to protect themselves from

gastric juice.

Peristalsis moves the chyme towards pylorus, which is then released

gradually into the duodenum (first part of the small intestines).

Digestion in the small intestine:

Chyme in the duodenum, specifically fat, stimulates the secretion of a

hormone cholecystokinin (CCK), which causes the gallbladder to contract to

release bile into the duodenum.

Bile is produced in the liver and stored in the gallbladder.

Bile has the function of fat emulsification (brings fat into suspension so

enzymes can act upon them).

Chyme stimulates the pancreas to secrete pancreatic juices into small

intestine.

The pancreatic juice contains enzymes that act on all three energy nutrients.

Pancreatic juices:

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- Pancreatic amylase (split starch to maltose)

- Trypsin (break down proteins to smaller molecule)

- Lipase (break down fats to fatty acids and glycerol)

- Sodium bicarbonate, which is basic (a neutralizing agent)

Intestinal juices (cells of the intestinal wall): lactase, maltase, sucrase,

peptidases.

Most of the other nutrients-vitamins, minerals, and water-need no such

disassembly; some are altered slightly, but most are absorbed as they are.

Absorption:

The passage of nutrients into the body fluids and tissues.

Nutrients must be in simplest form

Carbohydrates → glucose, galactose, fructose

Proteins → amino acids

Fat → fatty acids and glycerol

Most absorption of nutrients occurs in the small intestine through villi,

fingerlike projections from the folds of the small intestine, which are

composed of the microvilli, hairlike projections on each cell of every villus

that trap nutrient particles and transport them into cells.

Large intestine absorbs water and salts and collects bulk.

In healthy individuals more than 90% of the nutrients are absorbed.

Metabolism:

Complex process that changes the nutrients in order to produce energy,

which form tissues, and maintain control and regulation over body

functions.

Nutrients undergo oxidation

Carbohydrates, fats Co2 + H2 O

Proteins Co2 + H2O + N

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Anabolism: the formation of complex molecules from simpler ones

Catabolism: the breakdown of molecules to simpler ones like in surgery

burns and during period of high fever.

Metabolism is regulated by the thyroid gland.

Carbohydrates

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Definition: Carbohydrates are organic compounds that consist of carbon,

hydrogen, and oxygen arranged as monosaccharides or multiples of

monosaccharides. All carbohydrates except dietary fibers provide 4 kcal/g.

Sugars and Starches

Nature: Carbohydrates are formed from green plants through photosynthesis by

which sugar is formed from Co2 and H2O by the aid of sunlight and chlorophyll.

Functions:

1. Provide energy for body functions and heat to maintain body temperature.

2. Spare proteins for energy.

3. Aid in the synthesis of non-essential amino acids.

4. Required for the complete oxidation of fat.

5. Lactose increases the absorption of calcium and phosphorus and favors the

growth of certain intestinal bacteria that synthesize some of the B-complex

vitamins.

6. Gives flavor and texture to the diet.

Daily Requirements:

The daily diet should not contain less than 100 gms of carbohydrate.

About 55 to 60% of the total caloric intake should be provided through

carbohydrates.

Sources:

Cereal grains (rice, wheat, corn, oats, rye).

Green leafy vegetables are high in fibers.

Roots, tubers and seeds contain more complex carbohydrates (corn, potatoes,

dried peas, beans).

Fruits contain sugars and fibers.

Sweets provide different types of sugars.

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Animal sources include lactose in milk and glycogen in meats (limited extent).

Classification:

Class Examples

Monosaccharides (single sugars) Glucose

Fructose

Galactose

Disaccharides (double sugars) Sucrose

Maltose

Lactose

Polysaccharides (complex carbohydrates) Starches

Glycogen

Dextrin

Dietary Fibers

Monosaccharides (simple carbohydrates):

Simplest form of carbohydrates.

Requires no digestion and are absorbed directly from the small intestine.

Disaccharides (simple carbohydrates):

Lactose composed of glucose and galactose.

Principal carbohydrate of milk

Maltose composed of two glucose molecules.

Whenever starch breaks down

Fermentation process yields that yields alcohol

Minor constituent of a few foods

Sucrose composed of glucose and fructose.

Natural sweetness of fruits, vegetables, and grains

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Refined to make table sugar

These carbohydrates and all the other energy nutrients are put together

and taken apart by a similar chemical reaction: condensation and

hydrolysis.

Must be changed to simple sugars before they can be absorbed.

Maltose is an intermediate product in the digestion of starch inside the

body.

Polysaccharides (complex carbohydrates):

Starch is the plant storage form of glucose (long, branched or un-

branched chains of hundreds or thousands of glucose molecules).

Derived from plants

Richest in grains; wheat or rice, in tubers such as potatoes, and in

legumes such as peas and beans.

Glycogen is the form in which carbohydrates are stored in the body

(liver and muscles).

Dextrin is a digestible polysaccharide that is an intermediate product

from the hydrolysis of starch.

Fibers provide structures in stems, trunks, roots, leaves, and skins of

plants, which are compose of a variety of monosaccharides and other

carbohydrate derivatives.

Digestion, Absorption and Metabolism:

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The goal of digestion is to reduce the complex and double sugars to simple sugars.

Digestion

Mouth: cooked starch Small Poly, Maltose

Stomach: No action. Acid inactivates salivary enzyme.

Small intestine: Starch Maltose

Sucrose Glucose, Fructose

Maltose 2 Glucose

Lactose Glucose, Galactose

Absorption

Small Intestine: Glucose absorbed. Fructose and galactose can eventually

become glucose after being processed in the liver.

MetabolismGlucose Co2 + H2O + energyChanged to glycogen and stored in liver and muscles.Changed to fat and stored in fatty tissues.

Dietary fiber

- Divided into two groups

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Salivary amylase

Sucrase

Maltase

Amylase

Lactase

Oxidation

- Fibers that are not soluble in water (structural fibers): whole wheat and rye,

wheat bran, seeds, nuts.

- Water-soluble (nonstructural): apples, grapes, plums. Citrus fruits, oatmeal,

oat bran, beans.

Health benefits of fibers:

Increase sense of fullness

Reduces energy consumption, which helps in weight control.

Prevent constipation.

Increase fecal weight (promotes bowel movements).

Help prevent bacterial infection.

Reduces colon cancer.

Improve the regulation of blood sugar (delaying glucose absorption).

Lower the blood cholesterol and triglycerides (benefits heart health).

Glucose in the body:

Every body cell depends on glucose for its fuel to some extent, and ordinarily, the

cells of the brain and the rest of the nervous depend primarily on glucose for their

energy.

Homeostasis: the body must maintain blood glucose within limits that permit

the cells to nourish them-selves. If the glucose falls below normal, the person

may become dizzy and weak; if it rises above normal, the person may become

fatigued.

Regulating hormones:

o Primarily by two hormones (from cells in the pancreas): insulin, which

moves glucose from the blood into the cells, and glucagon, which

brings glucose out of the storage when necessary.

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o Epinephrine: another hormone of the adrenal gland that modulates the

stress response. Like glucagon, it works to release glucose from the liver

glycogen to the blood.

Proteins

Definition:

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- Proteins are large, complex, nitrogen containing compounds.

- In addition to the carbon, hydrogen, and oxygen that carbohydrates and lipids

contain, proteins also contain nitrogen.

- Each gram of nitrogen = 6.25g protein.

- Amino Acids: building blocks of proteins. Each contains an amino group

(NH2), a hydrogen atom, an organic acid/carboxyl group (COOH), and a

distinctive side group, all attached to a central carbon atom.

- Side group is a unique structure that differentiates one amino acid from

another.

- The kinds of amino acids, the order in which they are arranged, and the

frequency in which they are used in a chain determines the kind of protein.

- About 20 AAs with 20 different side chains make up most of proteins of living

tissue.

Classification:

Proteins are made up of about 20 common amino acids. Amino acids are classified

as essential (those the body can’t make - that must be supplied by the diet) and

nonessential (can be synthesized in the body).

Essential Amino Acids

Histidine (His) Valine (Val)

Isoleucine (Ileu) Lysine (Lys)

Leucine (leu) Methionine (Met)

Phenylalanine (Phe) Threonine (Th)

Tryptophan (Try)

Non-essential amino acids

Alanine Cysteine Proline

Arginine Glutamic acid Serine

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Asparagine Glutamine Tyrosine

Aspartic acid Glycine

Proteins:

- Cells link AAs end to end in a virtually infinite variety of sequences to form

thousands of different proteins. Each amino acid is connected to the next by a

peptide bond.

- The unique shapes of proteins enable them to perform their various tasks in the

body.

o Hemoglobin – packs the red blood cells and carries oxygen – is made of

four associated polypeptide chains, each holding the mineral iron.

- Heat, acid, or other conditions may disturb proteins’ stability, they undergo

denaturation, in which they uncoil and lose their shapes and, consequently,

their ability to function.

Daily Requirements:

- Many factors determine the requirements (body size, protein quality, new

tissue requirements, stress,…).

- 0.8 g/kg body weight for adults.

- 2.2 g/kg body weight for infants 0-6 months

- 1.6 g/kg for infants 6-12 months.

- 28 g/day for children 7-10 years.

- 71 g/day for pregnant and lactating.

Nutritional Quality of Proteins:

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The protein quality is of great concern, especially in countries where malnutrition

is of great concern. Low quality proteins fail to provide enough of all the essential

amino acids needed to support the body’s work.

Complete Protein:

- Contains the kinds and amounts of essential amino acids to support

maintenance & growth in relatively the same amounts that human

beings require. Generally proteins derived from animals (milk, eggs,

meat, poultry, Fish)

- Gelatin is a exception, it lacks tryptophan and cannot support growth

and health as a diets sole protein.

Partially complete Protein:

- Protein from plants in which one or more essential amino acids are

supplied in amounts inadequate for tissue synthesis (legumes, grains,

nuts)

Incomplete Protein:

- Some plant proteins are notoriously incomplete, in which one or more

of essential amino acids are absent (corn and soy proteins).

High quality protein: an easily digestible complete protein (egg protein, assigned

a value of 100).

Measurement of protein quality:

- Protein Efficiency Ratio (PER) =

Proteins of high quality have a PER of 2.5 or better.

Official method for assessing protein quality, and it is still used to evaluate

proteins for infants by the United States and Canada.

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Wt gain (g)

Protein fed (g)

- Biological value (BV) is measuring nitrogen content of the food eaten and the

nitrogen content of the urine and feces (protein nitrogen absorbed).

A BV of 70 or more is considered adequate for growth.

Sources:

- Animal sources include milk, eggs, cheese, meat, poultry, and fish.

Protein in these foods provides all the essential amino acids.

- Plant sources are beans, lentils, and other legumes, breads & cereals,

nuts, and seeds. Protein from these sources must be complemented with

another animal or plant proteins.

Functions of Protein:

1. Supporting growth and maintenance.

2. Supplies some energy upon need (4 kcal/g).

3. Supplies essential substances necessary for the construction and proper

functioning of body compounds (enzymes, hormones, regulators of fluid

balance, acid-base regulators, hemoglobin, transporters, antibodies, and others

such as being integral parts of most body structures as skin, bones, and

muscles).

Digestion, Absorption, and Metabolism:

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The goal of digestion is to release the amino acids that make up the protein

molecule.

Digestion

Mouth Crushed and moistened, mix with saliva

Stomach Protein proteoses peptones

Milk casein calcium caseinate

Small Intestine protein peptones Amino acid

Small intestine in the form of amino acid

- In the stomach:

o HCL uncoils protein strands and activates stomach enzymes

(pepsinogen to pepsin).

o Pepsin cleaves proteins – large polypeptides – into smaller

polypeptides and so AAs.

- In the intestines:

o Pancreatic and small intestinal enzymes split polypeptides further

(tripeptides, dipeptides, and AAs)

o Intestinal proteases hydrolyze peptides and then cells absorb them.

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Gastric Pepsin

Rennin

Trypsin* Erepsin

Absorption

Metabolism

Amino acids

- Build new tissues

- Repair old tissues

- Deamination (if not needed):

Nitrogen removed urea excreted

Carbon, hydrogen, oxygen glucose

Clinical Problems:

Protein excess:

- Protein intake urinary loss of Ca

- protein intake based on increased amount of meat, poultry, whole

milk in the diet will lead to increase intake of saturated fat.

- Protein rich foods are expensive this may lead to exclusion of other

foods that are needed for minerals and vitamins from the diet.

Protein deficiency:

- Nutritional edema

- Reduces the immune response

Protein-energy malnutrition (PEM): a deficiency of protein, energy, or both,

including kwashiorkor, marasmus, and instances in which they overlap.

- Kwashiorkor: older infants and young children (1 to 3 yr). The protein

content of the food is law.

- Acute PEM

- Protein deficiency, illness such as measles or other infection

- Loss of body wt and body fat not as severe as in marasmus, edema

(distinctive feature), belly bulges with a fatty liver.

- Marasmus: Infancy (less than 2 yr). The infant is fed a diet low in

calories and protein.

- Chronic PEM

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- Children look like little old people – just skin and bones, extreme

loss of muscle and fat.

- Muscles including heart waste and weaken.

In all cases, children are likely to develop diarrhea, infections, and multiple

nutrient deficiencies.

Fats

Composition

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- Composed of three chemical elements: Carbon, hydrogen, and oxygen.

- Fat is often used to refer to all the lipids, including triglycerides (fats and oils),

phospholipids, and sterols.

- The triglycerides - composed of one glycerol molecule attached to three fatty

acids – predominate, both in foods and the body.

- Each gram of fat yields 9 kcals.

Fatty acids

- Organic acids – a chain of carbon atoms with hydrogens attached – that has an

acid group (COOH) at one end and a methyl group (CH3) at the other end.

- Some fatty acids have short chains (fewer than 6 carbon atoms), others have

medium length carbon chains (6-10 carbon atom), and the most commonly

occurring in diet has long chains (12-24 carbon atoms).

- Long chain fatty acids include meats and fish; short and medium chains

primarily in dairy products.

- Fatty acids maybe saturated or unsaturated depending on the amount of

hydrogen in their composition.

- Saturated if there is a single bond between the carbon atoms (fully loaded with

hydrogen atoms and contains only single bonds between its carbon atoms).

- Unsaturated if there is a double bond between two carbon atoms (hydrogens

missing and presence of double bonds is an indication of unsaturated fatty

acids).

- One double bound monoustaturated.

- Two or more double bounds polyunsaturated.

Classification of lipids- Triglycerides (the chief form of fat in the diet and the major storage form of fat

in the body; composed of a molecule of glycerol with tree fatty acids attached),

and their component parts, fatty acids (few occur free in foods or in the body).

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- Phospholipids are fats in which another group has replaced at least one of the

fatty acids.

- Best-known phospholipid is lecithin.

- Each lecithin has a backbone of glycerol with two of its three attachments

sites occupied by fatty acids and a phosphate group with a choline molecule

occupies the third site.

- Unique chemical structure that allows them to be soluble in both water and

fat.

- Part of cell membranes; food industry uses them as emulsifiers.

- Sterols are compounds with a multiple-ring structure. Many vitally important

body compounds are sterols; among them are bile acids, the sex hormones

(testosterone), the adrenal hormones (such as cortisol), and vitatamin D, as

well as cholesterol (most famous sterol that the body makes and uses for its

functioning).

- Cholesterol in the body can serve as the starting material for the

aforementioned compounds.

- Structural component of cell membranes (cholesterol).

Properties- Fats are insoluble in water, but soluble in ether, chloroform, benzene, and

acetone.

- Rancidity (the change in flavor and odor of fats when they are oxidized) occurs

specially in fats that have a high proportion of unsaturated fatty acids.

- Hydrogenated fats are polyunsaturated vegetable oils in which hydrogen has

been added commercially to double bond carbons (monounsaturated and

polyunsaturated fats) making the fats more saturated (solid) and more resistant

to oxidation by a process known as hydrogenation.

- Molecules that remain unsaturated after processing change shape from cis

to trans, trans-fatty acids.

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- Trans fatty acids have health effects similar to those of saturated fats.

Functions1. Fat foods furnish 9 kcal/g; provide the body with energy.

2. Spare the burning of protein for energy.

3. Provide insulation under skin; help to maintain constant body temperature.

4. Serve as shock absorbers, supporting and cushion vital organs.

5. Facilitate the absorption of fat-soluble vitamins A, D, E, & K.

6. Food fats contribute flavor, palatability, and satiety to the diet.

Essential Fatty AcidsHuman body can make all except two and therefore, must be supplied by the diet:

- Linoleic acid (18-carbon omega-6 fatty acid with 2 double bonds).

- Linoleic acid is converted to arachidonic acid in the body. Arachidonic

acid is required for normal growth, healthy skin, regulation of cell

permeability, strength of capillaries, transport and metabolism of

cholesterol, and as a precursor of prostaglandin.

- Linolenic acid (18-carbonomega-3 fatty acid with 3 double bonds).

- Needed so body can make EPA (eicosapentaenoic acid) and DHA

(docosahexanoic acid).

- These are essential for normal growth and development, and may play an

important role in the prevention and treatment of heart disease,

hypertension, arthritis, and cancer.

- Both, in addition to serving as structural parts of cell membranes, they make

eicosanoids – powerful compounds that help regulate blood pressure, blood

clot formation, and the immune response to injury and infection.

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Recommended Intakes of FatThere is no daily-recommended allowance for fat. Fats should provide no more

than 30% of the total caloric intake. Other recommendations concerning fats are:

- Reduce saturated fat intake to less than 10% of calories, increase

polyunsaturated fats to about 10% of calories.

- Reduce cholesterol intake to less than 300 mgs daily.

Food sources- Animal sources are whole milk, butter, egg yolk, cheeses, and cream.

- Plant sources are vegetable oil (corn, sunflower, sesame, etc.) and salad

dressings made from oils, nuts, and olives.

Digestion, Absorption, and metabolism of fat

Almost all the digestion of fat occurs in the small intestine. Fat stimulates the

secretion of hormone CCK, which causes the gallbladder to contract so that the

stored bile is released into the small intestine. Bile breaks up the fat into tiny

particles and hold them in suspension in the watery intestinal content: this is

known as emulsification.

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Digestion

Mouth: No significant action, fats begin to melt (at body temp) Lingual lipase plays a small role in fat digestion

Stomach: fats Fatty acids and glycerol

Small intestine: emulsified fats Monoglycerides, fatty acids aand glycerol

Absorption

Small intestine: Glycerol and fatty acids absorbed into blood

stream

monoglycerides and fatty acids new fat

Metabolism Oxidized for energy Stored in adipose tissue Synthesis of phospholipids

*Pancreatic lipase**Intestinal lipase

In the large intestine: some fat and cholesterol trapped in fiber, exit in feces.

Transport:

The body makes four main types of clusters of lipids and proteins that are used as

transport vehicles for fats. As a group, these vehicles are known as lipoproteins,

and they solve the body’s problem of transporting fatty materials through the

watery blood stream.

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G. Lipase

P. Lipase*

I. Lipase**

Chylomicrons: They transport diet –derived lipids (mostly triglycerides) from

the intestine to the rest of the body.

VLDL: very low-density lipoprotein: made primarily by the liver cells to

transport lipids to various tissues in the body; composed primarily of

triglycerides.

LDL: low density lipoprotein: derived from VLDL lipoproteins as cells

remove triglycerides from them; chief carrier of cholesterol (bad fat).

HDL: high-density lipoprotein: high in protein: appear to reduce the risk of

coronary heart disease (good fat). Lipoprotein that transports cholesterol and

other lipids back to the liver from the cells for recycling or disposal.

Risk factors associated with increased fat intake:

Obesity

Cardiovascular diseases, Atherosclerosis, stroke, myocardial infarction

Hypertension

Diabetes

Some types of cancer

Energy metabolism

The body’s need for energy:

* The human body requires fuel to do its work. The energy needed for the body

takes priority over the maintenance and building of tissues or the regulation of

body functions.

32

* Glucose-from carbohydrates and glycerol and fatty acids-from triglycerides

provide most of the body’s energy needs. However, if the supply is inadequate

amino acids-from proteins will also be used for energy. Therefore:

* Glucose, fatty acids, glycerol, amino acids + oxygen Energy +

carbon dioxide + water

* The release of energy occurs during a series of pathways that ultimately lead to

the tricarboxylic acid cycle (TCA cycle) and electron transport chain (ETC),

which produce the greatest amount of energy.

* The energy released during catabolism is often captured by go-between

molecules that can easily transfer that energy to other compounds. These

molecules are sometimes called the body’s “common energy currency”, or

“high-energy compounds”. One such compound is ATP.

* Released energy is taken up in tiny packets known as ATP (adenosine

triphosphate). Energy can then be released from these tiny packets by

breaking one of the phosphate bonds, leaving a compound known as ADP.

ADP is rapidly regenerated to ATP.

Units of energy:

* Kcal is used to measure the energy value of the foods. Kcalories are units of

heat energy.

* Joule: mechanical equivalent of heat.

1 kcal = 4.2 kJ 1kJ = 0.24 kcal

Caloric value of nutrients /g

1 g CHO = 4 kcal = 17 kJ

1 g fat = 9 kcal = 37 kJ

1 g protein = 4 kcal = 17 kJ

33

* A bomb calorimeter is an instrument that measures the heat energy released

when foods are burned, thus providing an estimate of the potential energy of

foods.

Components of Energy Expenditure (energy needs of the body):

Heat is released whenever the body breaks down food for energy and again when

that energy is used to do work. The body’s generation of heat is known as

thermogenesis. The total energy a body spends reflects three main categories of

thermogenesis:

1. Basal thermogenesis (basal metabolism).

2. Exercise-induced thermogenesis (physical activity).

3. Diet-induced thermogenesis (thermic effect of food).

A fourth category is sometimes involved – adaptive thermogenesis (energy of

adaptation).

* The total energy requirement of the body includes the basal metabolism,

energy needed for activities, the influence of food, the environmental

temperature, and the special needs for tissue building during growth,

pregnancy and lactation.

* Basal metabolism (BM): energy needs of the body while at rest: includes the

involuntary activities of the body.

* Basal metabolism is the largest component of energy expenditure (about

2/3 of the energy the average person spends).

* It includes bodily activities that we can’t control. Examples are breathing,

heart beating, circulation of blood, peristaltic movements of the intestinal

tract, and the metabolic activities – in short, they support all the basic

processes of life.

* The basal metabolic rate (BMR) is the rate at which the body spends energy for

these maintenance activities. The rate may vary from one person to another.

34

* BMR is regulated by the thyroid gland.

Factors affecting BMR:

* Body size: Greater skin surface loses more heat.

* Age: Lean body mass diminishes with age, slowing the BMR.

* Height: In tall, thin people, the BMR is higher.

* Sex: BMR is 10% higher in men than in women

* Muscle mass and body fat: athletes have higher rate than the non-athlete (the

more the muscles mass the more heat loss).

* Fever: fever elevates BMR. For each degree increase in body temperature the

BMR increases 13%.

* Stresses: Raises the BMR (including many diseases and certain drugs).

* Environmental temperature: Both heat and cold raise the BMR.

* Fasting/starvation: Lowers the BMR.

* Malnutrition: Lowers the BMR.

* Hormones: The thyroid gland hormone thyroxin, for example, can speed up or

slow down the BMR.

* Growth: Building new tissues accounts for a high rate of BMR in infants.

Increase in metabolism during the growth period of adolescence and also for

the development of the fetus during the second and third trimesters of

pregnancy. Therefore, in children and pregnant women, the BMR s higher.

* Smoking: Nicotine increases energy expenditure.

* Caffeine: increases energy expenditure.

* Sleep: BMR is lowest when sleeping.

Diet-Planning Guides:

Diet planning is the bridge between nutrition theory and the food on the table. To

plan a diet that achieves all of the dietary ideals, a person needs tools as well as

knowledge. To help people plan diets, two most widely kinds of guides are

available:

1. Food group plans (FGP):

35

- The U.S. Department of Agriculture (USDA) released a new food guide,

MyPlate, to replace the Food Guide Pyramid.

- Describes the daily number of servings recommended for gender and age

groups.

- The five-food group (MyPlate) is part of a larger communication initiative

based on 2010 Dietary Guidelines for Americans to help consumers make

better food choices.

- The plan can provide a reasonable foundation for diet planning.

- For information on what’s in each group, how much is needed, what counts as

a cup, and health benefits, visit www.Choose MyPlate .gov .

Problems with the five food groups- It does not specify calorie amount.

- A person may fail to meet the daily needs for some nutrients.

- It ignores the needs of vegetarians.

In general food group plans organize foods by their nutrients and origins to

provide patterns of food intake that cover nutrient needs.

2. Exchange lists :

- Lists of foods that can be used with food group plans to help achieve kcalorie

control and moderation.

- The system sorts foods into three main groups by their proportions of

carbohydrate, fat, and protein and specifies their portion sizes.

- Provides a sense of which foods are similar to each other in their energy and

selected nutrient contents.

- Can facilitate weight control, controls fat intake (saturated vs.

polyunsaturated), fiber and salt intakes for preventing many diseases

36

- Organizes foods into three main groups according to their CHO, fat and protein

contents (and therefore, total energy content as well). Foods on any single list

can be used interchangeably.

Problems with the exchange system:

- It pays strict attention to portions.

- Foods are based on their content of CHO, fat, protein and not their content of

vitamins and minerals.

In general exchange system facilitates kcalorie control because foods on each list

provides approximately equal amounts of carbohydrate, fat, and protein, as well

total kcalorie.

Dietary guidelines for disease prevention:

Eat a variety of foods

Maintain healthy weight

Choose a diets low in fat, saturated fat, and cholesterol

Choose a diet with plenty of vegetables, fruits, and grain products

Use sugar in moderation

Use salt and sodium in moderation

37

38

Glucose

Pyruvic AcidAmino Acid

PROTEIN

Glycerol FAT

Acetyl CoA Fatty Acid

TCACycle

CO2 H2OEnergy

NH2

NH2

CARBOHYDRATE

Exchange List for Meal Planning--------------------------------------------------------------------------------------------------------

Groups/Lists Carbohydrate Protein Fat Calories (grams) (grams) (grams)

--------------------------------------------------------------------------------------------------------

CARBOHYDRATE GROUP:Starch 15 3 -- 80Fruit 15 -- -- 60Milk, skim 12 8 -- 90Milk, reduced fat 12 8 5 120Milk, whole 12 8 8 150Other Carbohydrates 15 varies varies variesVegetables 5 2 -- 25

MEAT AND MEAT SUBSTITUTE GROUPVery lean -- 7 0-1 35Lean -- 7 3 55Medium-fat -- 7 5 75High-fat -- 7 8 100

FAT GROUP -- -- 5 45

_____________________________________________________________________

(ADA & A Diet A, 1995)

39

Nutrition AssessmentNutritional assessment evaluates a person’s health from a nutrition perspective.

Many factors influence or reflect nutrition status. Therefore, nutritional assessment

includes:

Anthropometric measurments.

Physical examinations (clinical assessment).

Historical information (dietary assessment).

Biochemical analyses (laboratory evaluations).

Anthropometric Measurments

Anthropometrics are physical measurments that reflect body composition and

development.

Height

Weight

Skinfold

Circumferences

Height:

Malnutrition and certain illness during growing period can prevent an

individual from reaching optimal height.

Best obtained with standing straight with the back to a measuring device

attached to a vertical surface.

For infant and very young children recumbent (lying down) length is

measured.

Weight:

Measured using a beam-balance (preferred) or electronic scales – most

accurate types.

40

Pediatric scale is used for measuring the weight of infants and children too

young to stand.

Body mass index:

An index of a person’s weight in relation to height, which is useful for estimating

the risk to health associated with malnutrition.

BMI = Weight, kg / Height, m2

BMI < 18.5 = underweight

BMI 18.5 to 24.9 = normal

BMI 25 to 29.9 = overweight

BMI 30 = Obese

Skinfold/fatfold Measures:

Means for assessing the energy reserves in the form of fat.

Help distinguish between professional athletes and overweight individuals.

Triceps (TSF) and subscapular (SSF) measurements are most frequently taken.

Measurements are conducted using a caliper.

Other Measures of Body Fat and Lean Tissue:

Waist Circumference

Waist-to Hip Ratio

Hydrodensitometry

Bioelectric Impedance

Clinicians use many other methods to estimate body fat and its distribution.

Physical Examinations (clinical assessment)

Physical examinations are used to search for signs of nutrient deficiency or

toxicity.

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Many signs appear most rapidly in parts of the body where cell replacement

occurs at a high rate

Such as in the skin, hair, eyes, and digestive tract (including the mouth and

tongue), which are most frequently examined for possible nutritional

deficiencies.

The epithelial and mucosal cells have a rapid turnover rate so symptoms of

deficiencies may appear earlier.

Advantages: non-threatening, easy to obtain, most informative and

communicate much information about nutrition health.

Disadvantages: many physical signs are nonspecific; they can reflect any of

several nutrient defeciencies as well as conditions not related to nutrition.

Historical Information (dietary assessment)

Clues about present nutrition status become evident with a careful review of a

person’s historical data. Historical data used in nutrition assesments includes the

following:

Health history: current and previous health problems and family health

history that affect nutrient needs, nutrition status, or the need for

intervention to prevent health problems.

Socioeconomic history: personal, cultural, financial, and environmental

influences on food intake, nutrient need, and diet therapy options.

Drug history: mediations, dietary supplements, and alternative therapies

that affect nutrition status.

Diet history: nutrient intake excesses or deficiencies and reasons for

imbalances.

Evaluation of the diet history provides a record of a person’s eating habits and

food intake and can help identify possible nutrient imbalances.

42

Food choices are an important part of lifestyle and often reflect a person’s

thoughts.

Methods for collecting intake information includes the following:

1. 24-hour recall: The easiest and the most common methods of obtaining dietary

information. Provides data for one day only, in which the assessor asks the

client to recount everything eaten or drunk in the past 24 hours or for the

previous day.

Disadvantages:

Patient may not be able to recall the foods eaten.

Patient may not be able to estimate the amount of food eaten.

Patient may not be telling the truth.

The intake may not be a typical one.

2. Food frequency questionnaire:

A checklist of foods on which a person can record the frequency with ehich

he or she eats each day.

Helps pinpoint food groups and therefore, nutrients that may be excessive

or deficient in the diet.

Does not provide information on the quantities.

Useful when used with the 24-hour recall, enabling the assessor to double

check the accuracy of the information obtained.

3. Food record:

An extensive, accurate log of all foods eaten over a period of several days or

weeks, including the quantity and method of preparation. A food record that

includes associated information such as when, where, and with whom each food is

eaten is sometimes called a food diary.

43

4. Observation of food intake:

Members of the care team can obtain information about food intake and factors

affecting it in the hospital and at home through observing the clients.

5. Usual intake: An assesor asks questions about a person’s usual intake until a

typical daily pattern emerges.

Useful especially in verifying food intake when the past 24 hours have been

atypical, as well as helps the assesor verify food habits.

Difficult for a person whose diet intake varies widely from day to day.

Nutrition History:

Collect information on the general pattern of food intake and other factors

influencing the patient’s food habits.

Includes 24-hour recall, a food frequency list, an extensive interview and

through reading the patient’s medical record.

Estimating nutrient content of the diet:

Dietary intake is evaluated by comparing it to some standards

Biochemical Analyses (laboratory assessment)

Biochemical analyses help to determine what is happening to the body internally.

Common tests are based on analysis of blood and urine samples, which contain

nutrients, enzymes, and metabolites that reflect nutrition status. Low nutrient

concentrations in the blood may occur due to inadequate intake, impaired

absorption, transport, or metabolism, increased excretion, or combinations of the

above.

Nutrient levels including glucose, lipids, or minerals, hemoglobin, hematocrit,

erythrocyte, leukocyte, etc. counts are used to measure nutrient levels.

44

Low Hb can be obsereverd in cases of anemia, hemorrhage, and protien-energy

malnutrition while elevated in dehydration.

WBC may increase in cases of infections and leukemia

RBC counts would decrease in anemia, chronic infectious diseases and

hemorrahage and are elevated in dehydration.

Serum albumin and serum transferrin are depressed in protein malnutrition

Decreased lymphocyte counts are associated malnutrition, stress, trauma, and

lowered immune response.

Vitamins

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- Vitamins are organic essential nutrients containing carbon, oxygen, and other

elements that are required in tiny amounts for body processes, including

functions that promote growth, reproduction, or the maintenance of health and

life.

- Vitamins do not provide energy but they enable the body to use the energy

provided from fats, carbohydrates, and proteins.

- Vitamins are found in minute amounts in natural foods. Eating a balanced diet

can provide all the vitamins needed.

- Vitamin deficiencies can occur if the diet is not balanced, or if so much alcohol

is used. Just as an inadequate intake can cause harm, so can an excessive

intake.

- The amounts of vitamins people ingest daily from foods and the amounts they

require are measured in micrograms or milligrams, rather than grams.

Hypervitaminosis: excess of one or more vitamins.

- Vitaminosis means without vitamins. This word followed by the name of a

specific vitamin is used to indicate a serious lack of that particular vitamin.

Preserving vitamin content in food (minimize nutrient loss):

- Buy the freshest, unbruised vegetables and fruits.

- Use raw vegetables and fruits whenever possible.

- Prepare fresh vegetables and fruits just before serving.

- Heat canned vegetables quickly and in their own liquid.

- Follow package directions when using frozen vegetables or fruit.

- Use as little water as possible in cooking (boil water).

46

- Save the cooking liquid for later use in soups, stews…..etc.

- Store fresh vegetables and fruits in a cool dark place.

Classification of vitamins:

- Vitamins are grouped according to solubility. Vitamins A, D, E, and K are fat-

soluble while the B vitamins and vitamin C are water-soluble.

- Vitamins A and D are sometimes classified as hormones, and B vitamins can

be classified as catalysts or co-enzymes that assist certain enzymes in the

release of energy from food.

Fat-soluble vitamins:

- They require bile for their absorption due to being insoluble in water.

- They travel through the lymphatic system within chylomicrons before entering

the blood stream, where many of them require protein carriers for their

transport.

- Absorbed fat-soluble vitamins are stored primarily in liver and adipose tissue;

therefore deficiencies of these vitamins are slower to appear.

- Mega-doses of these vitamins can be toxic (since they are stored in liver).

Vitamin A:

Found in 2 forms

1. Active in the body: vitamin A “retinol, retinal, retinoic acid”.

2. Precursors of vitamin A: provitamin A, “Carotenoids”. Beta-carotene is

the most studied and greatest vitamin A activity.

Functions:

- Essential for maintaining healthy eyes (promoting vision), skin (participating

in protein synthesis and cell differentiation), and supporting reproduction and

bone and tooth growth.

47

- Aids in the prevention of infections by helping to maintain healthy mucus

membranes.

Sources:

- Retinoids are found in fat-containing animal foods, such as liver, fish liver oils,

butter, cream whole milk, cheeses (from whole milk) and egg yolk.

- Carotenoids are derived from plant foods such as yellow and dark green leafy

vegetables, in yellow and orange fruit.

Deficiency:

- Night blindness: slow recovery of vision after flashes of bright light at night or

an inability to see in dim light.

- Blindness: progressive blindness caused by severe vitamin A deficiency.

- Dry, rough skin (keratinization), epithelial tissues weaken, and decreased

mucus secretion.

- Increased susceptibility to infections: measles, pneumonia, severe diarrhea,

malaria, lung disease etc.

Vitamin D:

- Found in 2 forms:

D2 (ergocalciferol) and D3 (cholecalciferol).

- Different from all other nutrients in that the body can synthesize it, with the

help of sunlight, from a precursor that the body makes from cholesterol. Given

enough time in the sun, people need no vitamin D from foods.

- D3 is formed in humans by the sun’s ultraviolet rays that hit the precursor in

the skin.

- D2 formed is the plant version.

- Vitamin D is a prohormone because it is converted to a hormone in the human

body; vitamin D is heat stable and not easily oxidized.

Functions:

- Mineralization of bones including the teeth

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- Promote calcium and phosphorus absorption from the GI tract

- Regulation of calcium and phosphorus levels in the blood

The bones grow stronger and denser as they absorb and deposit these minerals.

Vitamin D is the director, but the star of the show is calcium.

Sources:

- Synthesized in the body through exposure to sunlight

- Food sources of vitamin D include fortified milk, butter, egg

yolks, liver, fatty fish and their oils, and fortified margarine.

Deficiency:

- Decreased calcium and phosphorus absorption (low production of the protein

that binds calcium), which results in poor bone and tooth formation due to

being undersupplied.

- Young children develop rickets (growth retardation and skeletal deformities) -

bowed legs are often the most obvious sign.

- Adults develop osteomalacia (softening of bone).

- Osteoporosis is a condition of reduced bone density (a disease characterized by

brittle, porous bones). Inadequate vitamin D sets the stage for a loss of calcium

from the bones, which can result in fractures.

Vitamin E:

- Called tocopherols. Alpha-tochopherol is the only active vitamin E in the

human body.

- It deteriorates when exposed to heat.

Functions:

- Acts as an antioxidant

1. Protection of cell structure from the adverse effects of free radicals.

2. Prevents the oxidation of PUFA, but it protects other lipids and vitamin A.

- Improves physical performance, enhances sexual performance, or cures sexual

dysfunction in males.

49

Sources: wheat germ, vegetable and seed oils, leafy green vegetables, nuts,

and margarine. (Animal foods are poor sources of vitamin E).

Deficiency:

- Primary symptom: increased rate of hemolysis in the RBCs (erythrocyte

hemolysis), due to oxidation of PUFA in their membranes

- Anemia

- Neuromuscular dysfunction involving the spinal cord and retina of the eye.

Vitamin K

Functions:

- Acts primarily in synthesis of blood clotting proteins.

- Synthesis of bone proteins that regulate blood calcium.

Sources:

- Billions of bacteria in the GI tract (mainly in small intestines) make the

vitamin; this source provides about half of a person’s needs.

- Other half from: rich foods include green leafy vegetables, liver, and members

of the cabbage family, fruits, cereals, and milk.

Deficiency:

- Defective blood coagulation (Hemorrhaging, uncontrolled bleeding).

50

Water-soluble vitamins:

- Include B vitamins and vitamin C.

- Absorbed directly into the blood.

- Dissolve in water; circulate freely in water filled parts of the body.

- Not stored in the body; kidneys detect and remove excess in urine.

- Possible to reach toxic levels when consumed from supplements.

Reminder – key info:

Several B vitamins form part of coenzymes that assist certain enzymes in

the release of energy from carbohydrate, fat, and protein.

A coenzyme is a small organic molecule that associates closely with certain

enzymes; many B vitamins form integral parts of coenzymes.

B1 (Thiamin):

Functions: part of coenzyme TPP (thiamin pyrophosphate) used in energy

metabolism of all cells.

Sources: whole-grain, fortified, or enriched grain products; moderate amount in

all nutritious food.

Deficiency:

- Loss of appetite (anorexia), fatigue, nervous irritability and constipation.

- Extreme deficiency causes the disease beriberi (characterized as wet, with

edema or dry, with muscle wasting), a disease that affects the nervous system,

heart and other muscles.

B2 (Riboflavin):

- sensitive to light

Functions:

- Essential for carbohydrate, fat and protein metabolism.

51

- Part of coenzymes FMN (flavin mononucleotide) and FAD

(flavin adenine dinucleotide) used in energy metabolism.

Sources: milk products (yogurt, cheese); enriched or whole grains; organ meats;

dark green leafy veg.

Deficiency: Ariboflavinosis: inflammation of the members of the mouth, skin,

eyes, and GI tract.

Cheilosis is sores on the lips and cracks at the corners of mouth.

Dermatitis; eye sensitivity (burning, itching).

B3 (Niacin):

Other names: nicotinic acid, nicotinamide

- Stable in foods, stand reasonable heat, acid and storage.

- Functions:

- Serves as coenzyme in energy metabolism.

- Part of coenzyme NAD and NADP used in energy metabolism.

Sources: meats, poultry, fish and peanuts, whole grain and enriched breads

and cereals, and all protein containing foods.

- Tryptophan (an amino acid) is a precursor of niacin. The body can

make it from the amino acid tryptophan; 1 mg niacin equals 60 mgs

tryptophan.

52

Deficiency:

- Essential for the prevention of pellagra, a disease that produces the symptoms

of diarrhea, dermatitis, dementia, and eventually death (often called “the four

Ds”).

- Other deficiency symptoms include blurred vision, abdominal pain, inflamed

tongue, depression, fatigue apathy.

Biotin:

Functions and sources:

- Part of a coenzyme used in energy metabolism, fat synthesis, amino acid

metabolism, and gluconeogenesis.

- Widespread in foods; organ meats, egg yolks; also produced by GI bacteria.

Requirements: needed in very small amounts

Deficiency: skin rash, hair loss, and neurological impairment (consumption of

raw egg whites, more than two dozens every day for several weeks, which contain

a protein than binds biotin and prevents its absorption).

Pantothenic acid:

Functions: Part of coenzyme A, used in energy metabolism.

- Involved in the more than 100 steps in the synthesis of lipids,

neurotransmitters, steroid hormones, and hemoglobin.

Sources: Widespread in foods; organ meats, poultry, mushrooms, avocados,

broccoli, whole grains.

53

Deficiency: Its symptoms involve a general failure of all the body’s systems and

include fatigue, GI distress, and neurological disturbances.

Vitamin B6:

Occurs in three forms - pyridoxine, pyridoxal and pyridoxamine.

Functions: part of coenzyme PLP (pyridoxal phosphate) used in amino acid

metabolism.

Enhances the conversion of tryptophan to niacin and to serotonin;

also to make red blood cells (heme, nonprotein portion of

hemoglobin).

Sources: fish, poultry, meats, potatoes, a few other vegetables (green)

including legumes, and fruits (purple) including noncitrus

ones, and fortified cereals.

Deficiency: early symptoms include depression, confusion; advance symptoms

include abnormal brain wave patterns and convulsions; scaly

dermatitis and anemia (small cell type – microcytic)

are other symptoms.

Folate: also known as folic acid or folacin, and chemical name is pteroylglutamic

acid (PGA).

- Destroyed by storage, processing, heat or oxidation.

Functions:

- Part of coenzyme THF (tetrahydrofolate) and DHF (dihydrofolate) used in

DNA synthesis and therefore in new cell formation.

54

Sources: fortified grains, green leafy vegetables, legumes (black beans,

kidney beans, and black eyed peas), liver and seeds.

Requirements: Adults: 400 g/d

Deficiency: Impairment of cell division and protein synthesis – processes

critical to growing tissue.

Two of the first symptoms are anemia and GI tract

deterioration. “megaloblastic anemia”, a condition in which

RBCs are large and immature, and unable to carry oxygen

properly.

Elevated homocysteine, which is an amino acid that cannot be

broken down without adequate folate

B12: (Cobalamin)

Functions: Vitamin B12 and folate are closely related: each depends on the

other for activation.

Part of coenzyme methylcobalmin and deoxyadenosylcobalamin

used in new cell synthesis; helps to maintain nerve cells;

reform folate coenzyme.

Sources: Animal products: meats, fish, poultry, eggs, dairy products, and

fortified cereals.

Deficiency: Most reflect inadequate absorption, not poor intake due to two

reasons: a lack of HCL or intrinsic factor.

55

Deficiency disease, pernicious anemia, is caused by atrophic

gastritis and a lack of intrinsic factor, and is characterized by

abnormally large immature red blood cells.

Deficiency symptoms include anemia of folate deficiency, sore

tongue, fatigue, and degeneration of peripheral nerves progressing to

paralysis.

Vitamin C (Ascorbic acid):

- Anti-oxidant properties (protects food from oxidation and defends body from

free radicals).

- Readily destroyed by heat, air alkalis.

Functions:

1. Enhances iron absorption.

2. Collagen synthesis (a fibrous structural protein that strengthens blood

vessels, forms scar tissue, provides matrix for bone growth).

3. Antioxidant, by losing its electrons to defend against free radicals.

4. Synthesis of hormones, including thyroxin.

5. Metabolism of amino acid.

6. Strengthens resistance to infection.

Sources: Citrus fruits, tomatoes, potatoes, melon, strawberries, magoes,

cabbage-type vegetables, and dark green vegetables (such as

broccoli and bell peppers).

56

Deficiency:

- Scurvy (a disease characterized by spongy and bleeding gums, loose teeth,

sore joints and muscles. Symptoms of the disease includes bruises, poor

wound healing, easily fractured bones).

- Symptoms include bleeding gums, loose teeth, bruises and rough skin, poor

wound healing, anemia and infection.

57

Minerals- Minerals are inorganic substances found in all body tissues and fluids.

- They do not furnish energy and are stable in water.

- Minerals are divided into two classes

Major minerals (macrominerals) are those that occur in largest amounts in foods

and in the body. Examples are Calcium, Phosphorus, Sodium, Potassium,

Chloride, Magnesium, and sulfur.

Trace minerals (microminerals) are those that occur in very small amounts in

foods and in the body. Examples are Iron, Iodine, Zinc, Selenium, Fluoride,

Copper, and Manganese.

General Functions:

- Bone and tooth formation

- Constituents of soft tissues, vitamins, enzymes, and hormones

- Nervous response and muscle contraction

- Water and acid-base balance

Dietary allowance:

- RDA for eight of the elements is set

- For other minerals a “safe and adequate” range of intakes has been

recommended.

- Based on weight, the allowance for infants, children, and teenagers are

higher to allow for growth.

- Allowances are also higher for pregnancy and lactation.

Factors that affect the absorption of minerals:

- Body need

- The chemical form of the mineral

58

- Stomach acidity

- Lactose improves Ca absorption

- Ascorbic acid enhance the absorption of Ca, Fe, Zn

- Some drugs and excess fiber bind minerals

- Laxatives and diarrhea decrease absorption

- Excess of some minerals decrease the absorption of other minerals

- Damage to the intestinal mucosa interferes with the absorption of minerals

MINERALS FOOD SOURCES FUNCTIONS DEFICIENCY

Major

minerals

Calcium

MilkCheeseSome dark green,

leafy vegetables

- Normal development and maintenance of bones and teeth

- Clotting of the blood - Nerve irritability- Normal heart action- Normal muscle activity - Activates enzymes

- Retarded growth- Poor tooth and bone

formation- Slow clotting time- Osteoporosis

Phosphorus Milk and CheeseLean meatPoultryFishWhole grain cerealsLegumesNuts

- Normal development and maintenance of bones and teeth

- Maintenance of normal acid-base balance of the blood

- Constituent of all body cells

- Necessary for effectiveness of some vitamins

- Poor tooth and bone formation

- Weakness- Pain in bones

Magnesium AvocadosNutsMilkWhole grainsGreen, leafy vegetablesLegumesBananas

- Constituent of bones, muscles and red blood cells

- Regulate the transmission of nerve impulses and activate enzymes including those involved in energy metabolism

- Severe prolonged vomiting

- Kwashiorkor severe malabsorption disease

- Impair central nervous system activity

59

MINERALS FOOD SOURCES FUNCTIONS DEFICIENCY

Sodium Table saltMeatMilk and cheeseSoy sauceProcessed foods

- Water balance & osmotic pressure

- Acid-base balance- Transmission of nerve

impulse- Muscle contraction- Cell permeability

- Nausea- Exhaustion- Muscle cramps

Potassium VegetablesFruits, especially oranges, Bananas, and prunes

- Osmosis- Fluid balance- Regulate muscle

contraction including heart muscle

- Cell metabolism

- Muscle weakness- Paralysis- Confusion- Abnormal heart

beats

Chloride Table saltMeatMilkEggsProcessed foods

- Osmosis- Fluid balance- Acid-base balance- Formation of

hydrochloric acid

- Do not occur in normal conditions

- Nausea- Exhaustion

Sulfur All protein containing foods (meat, poultry, fish, eggs)

- For building hair, nails, and all body tissues

- Constituent of all body cells

- Metabolism

- Unknown (no deficiency has been observed)

60

MINERALS FOOD SOURCES FUNCTIONS DEFICIENCY

Trace

Minerals

Iron

Red meatsFishPoultryShell fishEggsLegumesDried fruits

- Essential for formation of hemoglobin of the red blood cells and provision of oxygen to cells

- Constituent of cellular enzymes

- Anemia: Characterized by weakness, dizziness, reduced resistance to infection, loss of weight, and pallor

Copper SeafoodLegumesNutsWhole grain Cereals

- Essential for formation of hemoglobin and red blood cells

- Component of several enzymes

- Anemia- Diarrhea- Liver damage

Iodine SeafoodFoods grown in soil bordering salt waterIodized salt

- Formation of hormones in thyroid gland that help to regulate growth development, and metabolic rate

- Goiter (enlargement of the thyroid gland)

- Cretinism (a congenital disease characterized by mental and physical retardation)

Manganese

Whole grainsNutsVegetables

- Cofactor for several enzymes - Unknown

Zinc Protein containing foods:Seafood, especially oystersLiverMeatEggsMilk

- Component of insulin and many enzymes

- Involved in making genetic material and proteins

- Immune reactions- Transport of vitamin A- Wound healing- Taste perception- The making of sperm- Essential for growth

- Growth failure in children

- Loss of appetite- Skin changes

(dermatitis)- Impaired wound

healing- Loss of taste- Sexual retardation

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Fluoride Fluoridated waterSeafood

- Helps form bones and teeth; confers decay resistance on teeth

- Susceptibility to tooth decay

Cobalt Organ meatsMuscle meatsMilkEggs

- A component of vitamin B12 necessary for formation of the red blood cells

- Unknown

Selenium SeafoodsOrgan meatsOther meatsWhole grainSome vegetables

- Part of an enzyme that defends against oxidation

- Regulates thyroid hormone

- Associated with Keshan disease (predisposition to hear disease characterized by cardiac tissue becoming fibrous

Chromium MeatsUnrefined grainsVegetable oils

- Associated with insulin- Needed for energy

release from glucose

- Unknown

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WaterIn the body, water becomes the fluid in which all life processes occur. Water

constitutes about 60 percent of an adult’s body weight and a higher percentage of a

child’s. Water content is the highest in metabolically active tissues (muscles)

Functions:

* Component of most cells

* Regulate body temperature

* Act as lubricants around joints

* Elimination of waste products

* Act as a media for the chemical reactions

* Transport of nutrients to the tissue

* Serves as a solvent for mineral, vitamins, amino acids, glucose

and other molecules

Sources of water:

* Fluids (water, tea, coffee)

* Solid foods

* Metabolic water

Requirements:

* Insufficient data to establish EAR or RDA for Water

* Insufficient data available to make recommendations based on reduction of

chronic risk diseases

* BW can be lost quickly from PA and heat

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