Nutrition

Diet

• A diet is one’s usual pattern of food choices.

• Poor diet is a risk factor for serious chronic diseases that are major killers of Americans, such as:– Cardiovascular disease– Diabetes– Obesity– Certain cancers

Nutrients and Non-Nutrients

• Nutrients are substances in food needed for growth, repair, and maintenance of cells.

– Some nutrients regulate cellular activities.

– Some nutrients supply energy.

• Non-nutrients are substances in food that are not needed by the body.

– Some provide health benefits.

– Some can be toxic.

Phytochemicals

• Non-nutrient substances produced by plants that may provide health benefits.

• Fruits and vegetables are rich sources of antioxidant phytochemicals, including:

– Beta-carotene

– Lutein

– Anthocyanin

Antioxidants

• Antioxidants prevent or reduce the formation of free radicals, which are unstable and highly reactive atoms or compounds that can cause cellular damage.– Such damage may contribute to heart

disease and certain cancers.

Natural and Health Foods

• Natural foods are not necessarily more nutritious than foods that are not described as “natural.”

• Health foods such as honey, herbal teas, and cider vinegar provide nutrients, but there is little or no scientific evidence to support claims they prevent or treat various health conditions.

• Regardless of whether it’s natural or manufactured, a healthy food contributes to nutrient needs and is safe to eat.

Organic Foods

• Technically, any substance that contains the element carbon is organic.– Carbohydrates, proteins, fats, and vitamins

contain carbon; therefore foods that consist of these nutrients are organic.

• To be labeled “organic,” a food must meet certain standards.

• For example, fruits and vegetables labeled organic must be grown without the use of synthetic pesticides or fertilizers.

• Organic foods are not nutritionally superior to foods grown using conventional farming methods.

What Happens to Food in Your Body?

• Digestion is the process of breaking down large food molecules into nutrients.

• Absorption is the passage of nutrients through intestinal walls and eventually into the blood.

Metabolism

• Metabolism refers to all chemical reactions that take place in the body.– These reactions are necessary to power

muscular movements, synthesize and repair tissues, release and use energy, and produce enzymes and hormones.

– The amount of energy in food is commonly expressed as a number of “calories.”

Energy Supplying Nutrients: Carbohydrates

• Plants supply most of the carbohydrates in the diet.– The simplest carbohydrates are sugars

(monosaccharides).– Fruits, vegetables, and corn syrup are rich

sources of monosaccharides.– Glucose is blood sugar, a major energy source.– Fructose is the sugar in fruits.

• Starches are complex carbohydrates.• During digestion, starch is broken down into

glucose molecules.• Grains, beans, and certain vegetables are

rich sources of starch.

Carbohydrates (continued)

• In the United States, carbohydrates constitute about 44% to 47% of the typical person’s caloric intake.

• Recommended total carbohydrate intake is 55% to 65% of calories, primarily from starchy foods.

• Recommendations for simple carbohydrate intake range from 10% to 25% of calories.

• Health problems associated with carbohydrates include diabetes mellitus, metabolic syndrome, and lactose intolerance.

Myths About Carbohydrates

• Sugar does not cause hyperactivity, mental illness, or criminal behavior.– Tooth decay is the only health problem clearly

associated with sugar consumption.

• Honey is not nutritionally superior to sugar, and it should not be given to infants. – Honey may contain bacterial spores that

produce toxins and can be life threatening to infants.

Energy Supplying Nutrients: Fiber

• Plants make certain carbohydrates that the human body cannot digest.

• This material is called fiber.• Soluble forms of fiber swell or dissolve in water.

– Rich sources include apples, bananas, citrus fruits, carrots, kidney beans, and oats.

• Insoluble forms of fiber remains fairly unchanged in water.– Rich food sources include brown rice, wheat

bran, and whole grain products.

Fiber and Health

• Fiber helps prevent constipation, hemorrhoids, and diverticulosis.

• It may reduce the risk of colon and rectal cancers, cardiovascular disease, and type 2 diabetes.

• The average American does not consume enough fiber-rich foods.

–At least 25 grams of fiber are recommended each day.

Diabetes

• Diabetes mellitus (diabetes) is a group of chronic diseases characterized by the inability of the body to metabolize carbohydrates properly.

• Insulin helps glucose (“blood sugar”) enter cells where it is metabolized for energy.

• People suffering from diabetes produce no insulin, produce insufficient amounts of insulin, or respond abnormally to insulin.– As a result, blood glucose levels rise to

unhealthy levels.

Diabetes Mellitus (continued)

• Chronic high blood glucose levels can lead to:– Hypertension– Loss of vision– Nerve damage

• In the United States, poorly controlled diabetes is a major cause of:– Kidney failure– Blindness– Lower limb amputations

Diabetes Mellitus (continued)

• Additionally, having diabetes greatly increases one’s risk of cardiovascular disease.

• Type 1 and type 2 diabetes are the most prevalent forms.– People with type 1 diabetes require daily

injections of insulin.– Although it can develop at any age, most

cases are diagnosed in childhood.

Diabetes Mellitus (continued)

• Common signs and symptoms of type 1 diabetes:– Lack of energy– Listlessness– Frequent urination– Excessive thirst– Fruity odor in breath– Increased appetite with weight loss– Vision problems

Diabetes Mellitus (continued)

• Most people with diabetes have type 2.– The typical type 2 diabetic is overweight, older

than 40 years of age, and has a family history of the disease.

• Since 1990, the prevalence of type 2 diabetes has increased dramatically in the United States, particularly among black Americans and Hispanics.– The disease is also becoming more common

among children and adolescents.– Obesity, physical inactivity, and poor diet

contribute to the development of type 2 diabetes in children and adults.

Diabetes Mellitus (continued)

• Common signs and symptoms of type 2 diabetes:– Excessive thirst– Excessive urination– Vision problems– In women, recurrent vaginal infections – Skin sores that do not heal

• Type 2 diabetes can often be controlled by making changes in diet and regular exercise.

• Many diabetics, however, need to take medications to increase the production of insulin.

• Routine health checkups are essential to lessening the long-term damaging effects of diabetes.

Metabolic Syndrome

• A condition that increases the risk for cardiovascular disease and type 2 diabetes

• Signs:– Excess abdominal fat– Slightly elevated fasting blood glucose levels– Elevated blood lipid levels– Hypertension

• Cause: poor dietary habits

Lactose Intolerance

• Condition that involves the body’s inability to metabolize the sugar in milk

• Lactose intolerant people experience:

– Intestinal bloating

– Cramps

– Diarrhea, after consuming milk or milk products

Lipids• Lipids include cholesterol and triglycerides (fat).• Some fat is necessary for health.

– Each triglyceride has three fatty acids.• Fatty acids can be saturated,

monounsaturated, or polyunsaturated.• Saturated fat

– Animal foods generally contain more saturated fat than plant foods.

– Palm and coconut oils are exceptions; they are rich plant sources of saturated fat.

Lipids (continued)

•Monounsaturated fat–Olives, peanuts, and canola oil are rich

sources•Polyunsaturated fat–Corn, safflower, cottonseed, and walnut

oils are rich sources

Cholesterol

• Cholesterol is necessary for cell membranes and the production of vitamin D, bile, and certain hormones.

• It is found only in animal foods.

• Human body makes cholesterol.

• High blood cholesterol levels associated with increased risk of heart disease.

Lipids and Health

• High-fat diets often result in unwanted weight gain.

• Diets that supply too much saturated fat are associated with increased risk of heart disease.– In general, diets high in saturated fat raise

blood cholesterol levels to a greater extent than diets that contain cholesterol.

Lipids and Health (continued)

• Omega-3 fatty acids are certain unsaturated fats that are associated with lower risk of heart disease and may improve joint mobility in people with rheumatoid arthritis.– Rich food sources are canola and soybean

oils, walnuts, flax seeds, and fatty fish from cold water (i.e., wild salmon, herring, tuna, and mackerel).• Fish oil supplements are generally not

recommended (high intakes of omega-3 fatty acids can lead to problems with clotting).

Hydrogenated Fat

• Hydrogenation process hardens liquid oils into more solid forms, such as margarine and shortening.– Process makes unsaturated fat in oil

more saturated– Also produces an unhealthy type of fat

called trans fatty acid• Saturated fat and trans fatty acids are

harmful to health as they raise blood cholesterol levels.

Recommendations for Lipid Intakes

• Healthy adults should reduce total fat intake to 20% to 35% of calories.– No more than 10% of calories from

saturated fat.

• Adults should limit cholesterol intake to no more than 300 mg per day.

Proteins

• Proteins are needed to build, maintain, and repair cells.

• Comprised of 20 amino acids

• Nine amino acids must be supplied by diet (essential amino acids).

• Complete proteins have all 9 essential amino acids.

• Incomplete proteins lack one or more essential amino acids.

Protein Needs

• The average American consumes about twice the amount of protein needed.

• Excess protein does not build more muscle.– If the body needs energy, the extra amino

acids are used for energy.– If the body does not need energy, the extra

amino acids is converted to fat and stored.

• Vegetarian diets are based on plant rather than animal foods.– Vegans (total vegetarians) eat only plant

foods.– Lacto-vegetarians include dairy products.– Lacto-ovo-vegetarians consume eggs and

dairy products.• Vegetarian diets require careful planning to

obtain all the essential amino acids, vitamins, and minerals.

Vegetarian Diets

Nonenergy Supplying Nutrients: Vitamins

• Regulate growth, maintain tissues, and release energy from carbohydrates, proteins, and fats

• Provide no calories (energy)

• Needed in very small amounts

Classes of Vitamins

• Water-soluble vitamins– Eight B vitamins and vitamin C– Not stored in body

• Fat-soluble vitamins are A, D, E, and K– Excesses are generally stored in body– Vitamin A and D are the most toxic

Nonenergy Supplying Nutrients: Antioxidants

• Antioxidants are compounds that protect cells by reducing or preventing free radical formation.

• Include various phytochemicals, such as beta-carotene and vitamins E and C.

• Antioxidant supplements are not recommended. – High doses may promote cancer cell growth.

• Can be obtained by eating a variety of fruits, vegetables, and other plant foods.

Nonenergy Supplying Nutrients: Minerals

• Minerals are a group of elements that: – Regulate chemical reactions– Others are structural components

contained in organic molecules (i.e. iron in hemoglobin and calcium in bone and teeth)

• Small amounts are needed for health.• Excesses can create imbalances with

other minerals or toxicity.

Calcium

• Calcium is the most plentiful mineral in the body.– Calcium is needed for strong bones and

teeth.– It is involved in regulating blood pressure,

clotting blood, and muscular movements.– Bones store and release calcium as

needed.

Osteoporosis

• As people age, bones lose mineral density and strength.

• As a result, bones break easily.• Bones in hip, spine, and wrist are most

likely to break.• An estimated 10 million Americans over 50

years of age suffer from osteoporosis, especially menopausal women.

– Calcium-rich diet, weight-bearing exercise, vitamin D, and magnesium help maintain strong bones.

Iron

• Most of the body’s iron is in hemoglobin, which is in red blood cells.– The iron in hemoglobin picks up oxygen in the

lungs and transports it to cells.• Iron deficiency is one of the most common

nutritional disorders in the United States.– In severe cases, iron deficiency results in

iron-deficiency anemia.• Hemochromatosis (iron storage disease) can be

deadly.– A simple blood test can detect this condition.

Water

• Essential to life—one would die within days without water.

• Water– Dissolves and transports material in the body– Eliminates wastes– Lubricates joints– Is involved in many chemical reactions

• Water is lost through perspiration, urination, breathing, and bowel movements.

• Plain water, other beverages, and most foods, especially fruits and vegetables, supply water.

• Alcohol and caffeine act as diuretics, compounds that increase urinary loss of water.

Water (continued)

• Current recommendations:– Food and beverages should supply about 16

cups of water daily for men and 11 cups for women.

• Dehydration can be deadly.• Sports drinks replenish minerals and water that

are lost during prolonged, heavy exercise in which considerable sweating occurs.

• Eating a variety of foods and drinking plain water before and during regular exercise meets the water needs for most people.

Planning a Nutritious Diet

• The key features of a nutritious diet are nutrient adequacy and nutrient balance.

• By selecting a wide variety of foods you can usually obtain the essential nutrients you need.

• “Everything in moderation” is the best approach to planning a well-balanced and nutritionally adequate diet.

• The Dietary Guidelines are a list of general recommendations that focus attention on the association between diet and chronic disease.– The key recommendations are:

• Manage your weight at a healthy level. • Be physically active daily.• Consume a nutritionally adequate diet.• Consume fruits, vegetables, whole

grains, and fat-free or low-fat dairy foods.• Keep foods safe to eat.

The Dietary Guidelines: 2005

The Dietary Guidelines 2005 (continued)

• Consume 20% to 35% of calories from fat and limit your cholesterol intake to 300 mg daily.

• Consume fiber-rich foods and limit your intake of sugary foods.

• Restrict salt intake to less than 1 teaspoon daily.

• If you drink alcohol, do so in moderation. Avoid alcohol if you are pregnant, breastfeeding, under 21, driving, or operating other machinery.

Using Nutritional Labeling

• The FDA requires nearly every packaged food to have a nutritional label, allowing consumers to determine the nutritional value of most packaged foods.

• Nutritional labels provide information about:– Fat– Cholesterol– Sodium– Total carbohydrates– Fiber– Sugar– Protein

Across the Life Span

Nutrition During Pregnancy

• From conception until birth, the developing embryo/fetus depends on its mother for nutrients.– A woman’s diet before conception has a

significant impact on the health of her infant.– Women who are undernourished during

pregnancy have a high risk of miscarrying, having premature or underweight babies, and delivering babies with birth defects.

Across the Life Span (continued)

Current Infant Feeding Recommendations• Provide breast milk and a supplement that

contains vitamin D and iron for at least the first 12 months of life.

• Do not feed solid foods before 4 months.• Do not feed fresh whole or reduced-fat cow’s

milk before first birthday.• Iron-fortified formulas are acceptable, but

women should consider benefits of breastfeeding.

Across the Life Span (continued)Child Nutrition •Most children eat enough food to maintain normal

growth.•Parents serve as role models as children

establish food preferences and eating habits.•Eating breakfast is an important habit to develop

early in life.•Poor eating habits can result in:

– Lack of energy– Difficulty concentrating on school work– Behavioral problems

Across the Life Span (continued)

Elderly Nutrition • Physical, social, psychological, and economic

factors often influence the quality and quantity of an elderly person’s food intake.

• As a result of aging, absorption of calcium, iron, and vitamins D and B12 declines.

• Vitamin/mineral supplement may be needed.• Many communities offer feeding programs for the

elderly such as Meals-on-Wheels and congregate meals.

• In addition to providing nutritious food, such programs offer social contact that can reduce the risk of depression.