Diet Therapy

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Diet Therapy

Definition

Diet therapies are specially designed and prescribed for medical and/or general nutritional reasons.

Purpose

Today's major health care problems are increasingly the result of acute and chronic conditions related to poor nutrition and/or overconsumption. A large proportion of coronary disease and cancer can be attributed to unhealthy eating habits and obesity. Chronic diseases continue to increase due to such factors as the rise in obesity in the American population.

Diet therapy promotes a balanced selection of foods vital for good health. By combining foods appropriate for each individual and drinking enough water, one can help maintain the best possible health. Eating a proper diet is critical for the health of individuals, groups with special medical and dietary needs, and entire populations afflicted with malnutrition.

Individualized diet therapy can provide the patient important insight into food-related illnesses and education regarding how various nutrients (protein, carbohydrate, fat, alcohol) affect illness, diseases, or obesity. Dietary therapy can be tailored to meet the treatment needs of patients on diagnosis of specific illnesses, can help reduce complications and/or side effects, and can improve general well-being.

Precautions

A particular modified diet is prescribed specifically for each individual. Those individuals who have medical conditions or who are sensitive to certain foods need to be very compliant and cautious about what they eat.

Individuals should not follow a "fad" diet without first consulting a registered dietitian or physician. Popular (but sometimes dangerous) low-carbohydrate diets, for example, may deprive the body of the glucose it needs for central nervous system and brain functions.

Description

Nutrition is the science concerned with the human body's use of nutrients and food substances. Proper nutrition decisions are important for the optimal health of each individual. This is especially true for those individuals with specific dietary needs and acute or chronic diseases. The nutrients necessary to maintain normal growth and health include proteins, carbohydrates, fats, vitamins, and minerals. Included in these nutrients are eight amino acids the body cannot produce but that must be derived from proteins, four fat-soluble and 10 water-soluble vitamins, 10 minerals, and three electrolytes.

Nutrient classes

PROTEIN. Protein is important for building body tissue and synthesizing enzymes. Enzymes are specialized organic substances that act to regulate the speed of chemical reactions in human metabolism. Twenty amino acids of the 100 or more occurring in nature make up proteins. Animals and plants are quick and available sources of what are termed "essential" amino acids; they are called essential because the body cannot build them internally. Normal growth and health are dependent upon these essential amino acids. Dietitians recommend that a healthy diet includes 10-20% of daily calories from protein (poultry, fish, dairy, and vegetable sources).

CARBOHYDRATES. Carbohydrates provide most of the energy in the majority of human diets. Foods rich in carbohydrates are usually the most abundant and cheapest. The carbohydrates containing the most nutrients are the complex carbohydrates, such as unrefined grains, tubers, vegetables, and fruits. Simple carbohydrates or sugars should be eaten in moderation, since they are high in calories but low in nutrients.

Carbohydrates are needed in the form of glucose by the brain and central nervous system (CNS). A minimum of 1.6 oz (50 g) of glucose is required daily for proper functioning of the CNS. If the body is denied carbohydrates, it will use ketone bodies for energy, but this is not a good energy source for the body, and may have unfavorable health effects.

FATS. Fats supply energy and essential fatty acids and promote absorption of the fat-soluble vitamins A, D, E, and K. The accumulation of body fat has become a serious health concern; almost two-thirds of Americans are considered overweight. Fats are compact fuels efficiently stored in the body for later use when carbohydrates are in short supply. Fats produce more than twice as much energy as carbohydrates, approximately 9 Kcals/gram versus about 4 Kcals/gram for carbohydrate and protein. Dietary fats are broken down into fatty acids that pass into the blood. These fatty acids are either saturated or unsaturated (monounsaturated, polyunsaturated, or transunsaturated). Saturated fats, derived mostly from animal sources, have been found to raise the level of total cholesterol in the bloodstream, and certain unsaturated fats tend to lower the level of total cholesterol in the blood stream. For example, monounsaturated fats like oleic acid in olive oil reduce low-density lipoprotein cholesterol (LDL, what is considered bad cholesterol) and increase high-density lipoprotein cholesterol (HDL, also known as good cholesterol), thus reducing the risk of heart disease. Saturated and transunsaturated fatty acids both raise serum cholesterol; in contrast, neither monounsaturated nor polyunsaturated fats have this effect.

INORGANIC MINERAL NUTRIENTS. Inorganic mineral nutrients are required to build tissues. They are also important for muscle contractions, nerve reactions, and blood clotting. All of these mineral nutrients must be supplied in the diet. Minerals are categorized as major elements or trace elements. Major elements consist of calcium, phosphorus, magnesium, iron, iodine, and potassium. Trace elements include copper, cobalt, manganese, fluorine, and zinc.

VITAMINS. Vitamins increase the breakdown and absorption of proteins, carbohydrates, and fats. Certain vitamins help form blood cells, hormones, nervous system chemicals, and genetic materials. Vitamins are classified into two groups: fat-soluble vitamins, such as A, D, E, and K; and water-soluble vitamins, such as vitamin C and the B-vitamin complex. Fat-soluble vitamins are usually found in foods that contain fat. Because excess amounts are stored in the body's fat and in the liver and kidneys, fat-soluble vitamins do not have to be consumed every day. The water-soluble vitamins, C and B complex, cannot be stored and must be consumed daily to replenish the body's supply.

Food types

Foods can be widely grouped into breads and cereals; legumes, tubers or starchy roots; vegetables and fruits; meat, fish, and eggs; milk and milk products; fats and oils; and sugars. Breads and cereals are high in starches (carbohydrates), but whole cereals also often supply significant amounts of protein. However, these cereals should be eaten in conjunction with other protein foods to supply all the essential amino acids. Meat, fish, and eggs supply all the essential amino acids that the body needs to build its own proteins.

Milk and milk products also provide a plentiful amount of protein, phosphorus, calcium, and vitamins. Legumes are rich in starch but also furnish more protein than cereals or tubers. Tubers provide a variety of minerals and vitamins. Vegetables and fruits are a direct source of many minerals and vitamins. Fats and oils are high in calories but usually contain few nutrients. Sugars, which are heavily consumed in more affluent countries, contain few nutrients and can cause tooth decay.

Dietary guidelines

A guide to the amount an average person needs to remain healthy has been determined for each vitamin and mineral as well as macronutrients. In the United States, this guide is called the Dietary Reference Intakes (DRI). Dietary counselors may use the DRI as a guide when providing counseling. A dietitian can advise the patient about any vitamin or mineral inadequacy concerns during the dietary counseling session. The DRIs have replaced the Recommended Dietary Allowance (RDA), but encompass both the RDAs and the upper intake limits for each nutrient.

The Dietary Guidelines for Americans, published by the USDA and Health and Human Services, can provide a broad overall view of good nutrition. They provide science-based guidance to promote health and reduce risk for major chronic diseases through diet and physical activity. These dietary guidelines include these basic recommendations:

eat a variety of foods; let the food pyramid guide your food choices
control weight
be physically active each day
eat a diet low in saturated fat (less than 10% of total calories) and cholesterol (less than 300 mg/day), and moderate in total fat (20-35% of total calories)
limit intake of fats and oils high in saturated and trans-fatty acids
eat a variety of vegetables and fruits, and whole grains
eat a variety of whole-grains
eat sugar in moderation
use salt in moderation
if you drink alcohol, do so in moderation; no more than two drinks per day of wine, beer, or spirits
keep food safe to eat; follow the government safety precautions as outlined on the food package

Energy requirements

Carbohydrates, proteins, and fats provide energy in the form of calories to fuel the body for metabolic processes, growth, and activity. When an individual consumes as many calories each day as the body uses, they are in a state of energy balance and will neither gain nor lose weight. When more calories are eaten than the body uses, the excess calories are stored as fat and weight increases. On the other hand, when fewer calories are consumed than the body needs, stored fat and muscle is burned for fuel and weight decreases. The amount of energy required depends on such factors as an individual's weight, gender, age, and activity level, so an estimation should be made based on these parameters. The DRIs provide energy (caloric) estimates based on activity level (sedentary, low active, active, very active) and body mass index. An equation is used to calculate energy needs based on these parameters in addition to age and gender. Using the metric system nomenclature, a kilojoule (kJ) is used instead of a kilocalorie (kcal), where 1 kcal = 4.184 kJ and F1 megajoule (MJ) = 1000 kJ.

Calorie-modified diet

Calorie-modified diets are prescribed to correct weight problems with a healthy diet. Low-calorie diets are designed for weight reduction and are prescribed for people who are overweight or obese. High-calorie diets are recommended for people with greatly increased energy needs such as athletes in training or individuals fighting diseases such as cancer, AIDS, or cystic fibrosis. High-calorie diets are also prescribed to treat anorexia nervosa.

Calorie-modified diets are planned by dietitians and should be prescribed following a complete physical examination and dietary assessment or dietary history. A low-calorie diet provides enough energy to meet the person's metabolic needs and activity level. It includes a balanced variety of foods, but limits carbohydrates and alcohol. A low-calorie diet should not aim to promote a weight loss of more than approximately 1-2 lb (500 grams to one kilogram) per week. In general, for a slightly overweight person, it is not wise to lose more than 1 lb (about 500 grams) per week. A high-calorie diet usually provides an extra 500-1,000 calories, leading to a weight gain of about 1 lb (500 grams) per week for most people. It has a high protein content, normal fat content, and emphasizes foods that pack many calories into a small volume. Snacking between meals is encouraged as a way to increase the calories consumed.

When caloric limits allow, have no more than two drinks of wine, beer or liquor per day.

Fiber-modified diet

Fruits and vegetables are excellent sources of fiber. Fiber has important nutritional benefits such as facilitating the movement of food through the digestive tract, helping to prevent constipation. Research suggests low dietary fiber may be responsible for increasing the incidence of diverticulosis and may also be associated with cancer of the colon.

High-fiber diets, including whole grains (especially bran), raw vegetables, unpeeled fresh fruits, nuts, and seeds, are recommended to:

increase fecal bulk
increase intestinal movement
prevent or treat constipation, diverticulosis, Crohn's disease, or irritable bowel syndrome
help lower cholesterol
assist with weight loss in people who are overweight and improve sugar tolerance in diabetics

Low-fiber diets exclude raw fruits and vegetables, whole grains, nuts, and seeds, while emphasizing soft, mild foods. They are recommended to:

decrease fecal bulk
slow intestinal movement
decrease stomach acid secretion
treat a variety of disorders including indigestion, diarrhea, bowel inflammation, and heart attack

Protein-modified diet

High-protein diets are designed to provide about 0.05 oz (1.5 g) of protein for each kilogram of a person's body weight. Complex proteins, such as milk and meats, should make up one-half to two-thirds of the daily protein requirement. High-protein diets are recommended for people who:

have an increased need for protein due to proteincalorie malnutrition, severe stress, or conditions such as AIDS, cancer, or burns with high metabolic rates that lead to the loss of large amounts of protein
have malabsorption syndromes, celiac disease, or other disorders characterized by poor food absorption

A low-protein diet excludes dairy products and meats, and requires that about three-fourths of the daily food intake of protein come from high-value protein sources. Supplements may be prescribed to prevent amino acid deficiencies. Low-protein diets are used in treatment of cirrhosis and kidney disease.

Low-cholesterol diet

Dietary modification is the first weapon in the fight against the high cholesterol levels that contribute to heart disease and atherosclerosis. Low-cholesterol diets are prescribed to reduce the risk of heart disease and to treat atherosclerosis, diabetes, high serum cholesterol (which may be hereditary and might also require cholesterol-reducing drugs), and high blood pressure. A low-cholesterol diet is not a cure for the conditions it is prescribed to treat, so most people must stay on the diet for the rest of their lives.

The American Heart Association eating plan recommends that total cholesterol intake should be less than 0.01 oz (300 mg) per day and total fat intake should be 30% or less of total calories. Saturated fatty acid intake should be less than 10% of calories or for anyone with elevated blood cholesterol levels or heart disease, saturated fat and cholesterol intake is limited even further to 7% of total calories per day.

The AHA eating plan also suggests:

Polyunsaturated fatty acid intake should be 8-10% of calories.
Monounsaturated fatty acids should make up the rest of the total fat intake, up to 15% of total calories.

These guidelines apply to all healthy individuals over two years of age.

Low-fat diet

Most American diets contain too much fat. Fat often makes up about 40% of total calories consumed each day. Dietary guidelines recommend limiting fat to 20%-35% or less of daily calories, since consumption of too much fat has been linked to obesity, heart disease, and several types of cancer. A low-fat diet usually limits daily fat intake to 1.76 oz (50 g), while an extremely low-fat diet limits fat consumed each day to 0.88-1.05 oz (25-30 g). The grams of fat in your diet will depend on the calories you need. Low-fat diets are recommended to:

help prevent heart disease
help prevent colon, prostate, and breast cancers
help treat a variety of conditions including gout, AIDS, gallbladder disease, liver disease, celiac disease, inflammatory bowel disease, and heartburn
lose or control weight

Some fat is required in the diet to prevent essential fatty acid deficiencies, but most people consume more than enough fat to meet these needs. Cutting back on fat will likely help individuals eat fewer calories, thus reducing weight and helping to prevent coronary diseases.

Gluten-free diet

Gluten and gliadin are proteins found in certain grains and grain-containing products. These proteins are toxic to cells within the intestinal tract of an individual who is "intolerant" and cause difficulty in food absorption. Celiac disease is caused by intolerance to these proteins. This intolerance causes patients with celiac disease to suffer weight loss, diarrhea, malnutrition, and bloating. By eliminating foods containing gluten from the diet, further damage to the intestines can be prevented, symptoms are relieved, and malabsorption of nutrients is corrected. A gluten-free diet eliminates all foods containing wheat, rye, barley, and malt, and must be followed for life.

Low-purine diet

This diet restricts food, such as sardines, liver, and eggs, that cause the body to produce uric acid. It is usually prescribed as part of a treatment program for gout (a disease usually caused by having too much uric acid in the body) and kidney stones, which also includes exercise and medication. In addition to excluding organ meats (sweetbreads, liver, kidney) and certain types of fish (anchovies, sardines, mackerel) and limiting the amount of other purine-containing foods such as shrimp, meats, and dairy products, this diet emphasizes drinking about 2 qt (1.89 l) of water and fruit juice daily, to promote the excretion of uric acid, and eating fruits and vegetables that increase urine alkalinity and the solubility of uric acid.

Low-salt diet

On the average, Americans consume about 0.17 oz (5 g) of salt or sodium daily. Dietary guidelines suggest that 0.08 oz (2.4 g) of sodium should be the upper limit, even if there are no signs of heart disease. Most people with heart disease should limit their sodium intake to less than 0.07 oz (2 g) a day, and some low-salt diets restrict sodium to as little as 0.008 oz (250 mg) per day. The amount of salt in the diet is important for people who have high blood pressure or congestive heart failure.

Some experts believe excessive intake of salt is a major reason for high blood pressure, especially in Western countries. Excess sodium encourages the body to retain fluid, thereby increasing fluid pumped by the heart and circulating in the bloodstream. Diets high in salt also can be harmful to people with congestive heart failure because the excess fluid backs up into the lungs, causing congestion.

Potassium chloride is a common ingredient in salt substitutes. But too much potassium can be harmful for people with kidney problems. One way to enhance the flavor of food while eliminating salt is to add lemon juice, herbs, spices, or flavored vinegar.

Low-phenylalanine diet

A low-phenylalanine diet is normal treatment for phenylketonuria (PKU). PKU is a rare genetic disorder in the degradation of dietary phenylalanine that if left untreated, can result in severe progressive mental retardation. The diet is extremely restrictive, and rigorous dietary compliance is necessary to reduce or prevent mental retardation. Close supervision by a registered dietitian or physician is necessary.

A normal diet cannot be tolerated by people with PKU. Dietary treatment necessitates avoiding foods containing high levels of protein. A prescribed diet contains only the amount of phenylalanine that is essential for the body. Basic principles of the PKU diet state that:

Meat, fish, cheese, eggs, milk, and nuts are not allowed because they are rich in protein and thus phenylalanine.
Other foods which contain moderate amounts of protein (e.g., potato and cereals) are given in small measured quantities. These foods are spread out between the day's meals to keep the phenylalanine levels steady.
Most fruits, some vegetables, and salads can be taken in normal quantities but excessive use should be avoided.
Sugar, jam, syrups, and fats such as butter, lard, and cooking oil can be used fairly freely.
There are many low-protein manufactured foods available on prescription. These can all be taken freely to provide variety in the diet. Foods include pasta, low-protein bread, biscuits, flour, spaghetti, etc.
Infants can be fed phenylalanine-free formulas.

There is a high incidence of tooth decay among individuals affected by PKU because of the increased amounts of carbohydrates consumed.

Diabetic diet

For the most part, dietary management is the key to keeping diabetes in check. There no single diet that meets the needs of all diabetics. The general rules for healthy eating as discussed previously apply to diabetics as well.

Several dietary methods are available for controlling blood sugar levels. The Dietary Guidelines for Americans can be followed by everyone over 2 years old, including diabetics. Some experts believe these dietary guidelines may be sufficient for diabetics, although there are more detailed dietary methods available for controlling blood sugar. These methods may be complex, however, which deters many diabetics from using them. The American Diabetic Association developed the Diabetic Exchange Lists, the most common system used for controlling blood sugar. Other nutrition experts recommend adopting a Mediterranean diet because they point out the food pyramid has some drawbacks; for example, there is little focus on meal planning. Carbohydrate counting plans may assist but may also be complicated and require a committed learner; the concepts of the Diabetic Exchange Lists may be difficult to understand for some people.

Type 1 and type 2 diabetics on insulin or oral medication must focus on controlling blood glucose levels by coordinating food intake with insulin administration or medication, or other variables such as exercise.

Nutrition habits that assist in glucose control:

Stick to a meal plan.
Appropriately treat hypoglycemia (low blood sugar).
Quickly respond to hyperglycemia (high blood sugar).
Maintain consistent snacking habits.

The recommendation given by the American Diabetes Association is to eat more complex carbohydrates. This is the opposite of what has been advised in past years. Current research studies now show it is healthiest for everyone to eat more grains, beans, and starchy vegetables to control fat and cholesterol. Total carbohydrate intake has greater impact on blood glucose control than the source of carbohydrate. However, consumption of complex carbohydrates (e.g., whole grain bread, beans, etc.) are better than eating foods that are sucrose (simple sugar) based.

Both weight loss and blood sugar control are particularly important for overweight type 2 diabetics who are not taking medication. Health effects are most beneficial after initial weight loss. A 10% decrease in body weight can control the progression of type 2 diabetes. Other important issues are controlling lipid (cholesterol and triglyceride) levels, and blood pressure. Controlling fat intake is important because diabetics are about twice as likely to get cardiovascular disease compared to other people.

Research shows that diabetics have the same protein requirements as other people, but with onset of nephropathy, protein should be limited to 0.8 grams/kg per day for adults, with 80% coming from high biological value protein.

Traditional diets may offer some health advantages

Certain populations have dietary habits that are much healthier than the typical Western diet, which is often too high in fat and cholesterol. Research has shown that the traditional Mediterranean diet, Japanese diet, or "hunter-gatherer" diets have health advantages. The dietary habits characteristic of Mediterranean countries with the consumption of olive oil (monounsaturated fatty acid) as the main fat source appear to provide optimal health benefits with a low incidence of coronary heart disease. The Mediterranean diet consists of large amounts fruit, vegetables, pulses, nuts, cereal products, and fish, while generally only small amounts of meat and dairy foods are consumed.

Preparation

Effective estimation of an individual's diet is required in order to provide dietary counseling and guidance. If a dietary assessment is not conducted in preparation, using proper methodologies, it will be difficult for the dietitian to draw any conclusions regarding the need for diet therapy.

Despite the diet type, all foods should be prepared appropriately. This includes adequate cooking time and proper storage. Some diets must be phased in gradually.

Aftercare

Regular follow-up with a dietician or physician is always important when an individual has been placed on a special diet because of a health condition.

One cannot live on "a diet" permanently, because strict guidelines are difficult and painstaking to follow. Therefore, dietary modifications have to be about lifestyle changes in food selections and healthier attitudes regarding nutrition and wellness.

Risks

There is always the possible risk of non-compliance of any diet. However, when the individual is placed on the appropriate diet and the primary physician is aware of any known allergies, there are very few risks involved, if any.

Results

When special diets are followed as prescribed, better health is the expected outcome, with a decreased risk of acquiring many diseases. However, it is up to an individual to implement the necessary dietary modifications. If a patient does not follow the recommended dietary guidance, then they will not benefit. Typically, modest effects are seen in weight loss or reduction in serum lipids (cholesterol) often due to failure to fully comply with the dietary recommendations provided by a dietitian or doctor.

The outcome of any diet therapy will be better when combined with exercise unless the patient is unable to exercise for medical reasons.

If the appropriate diet is prescribed by medical professionals, abnormal results are very rare.

Health care team roles

A certified nutrition professional such as a registered dietician (R.D.) should be seen for a dietary assessment and professional dietary counseling prior to commencing diet therapy. Beware of individuals prescribing diets without an education in dietetics and nutrition. In general, only registered dietitians have sufficient training and knowledge to accurately assess the nutritional adequacy of a patient's diet, especially if chronic disease is present. Some dietitians call themselves nutritionists, but the term "nutritionist" is not regulated by law; therefore anyone can call themselves a nutritionist. A doctor may also have a nutrition background or specialization and may thus be able to conduct a dietary assessment or to provide general nutrition advice and/or diet therapy. However, many physicians do not have any specialized knowledge in dietary therapy because they have not studied nutrition.

KEY TERMS

Calorie— Commonly referred to as a calorie, but is actually a kilocalorie (kcal). A kilocalorie is the energy required to raise the temperature of one kilogram of water one degree Celsius. It is how the energy content of food is measured.

Dietary assessment— An estimation of food and nutrients eaten over a particular time point. Some of the most common dietary assessment methods are food records, dietary recalls, food frequency questionnaires, and diet histories.

Dietitian— A dietitian is a health professional who has a bachelor's degree, specializing in foods and nutrition, and in addition undergoes a period of practical training in a hospital or community setting. Many dietitians further their knowledge by pursuing master's or doctoral degrees. The title "dietitian" is protected by law so that only qualified practitioners who have met education qualifications can use that title.

Electrolytes— Any of the various ions, such as sodium, potassium, or chloride, required by cells to regulate the electric charge and flow of water molecules across the cell membrane.

Kilojoule— In Europe and other countries, food energy values are frequently given in kilojoules (kJ), the metric unit of energy. Using the metric system nomenclature, a calorie is converted into a kilojoule (kJ), where 1 kcal=4.184 kJ and 1 megajoule (MJ)=1000 kJ. To convert kilojoules to kcals, divide by 4.184.

Legumes— A pod, such as a pea or bean, that splits into two valves with the seeds attached to one edge of the valves.

Nutritionist— Some dietitians call themselves "nutritionists" but in general, the term "nutritionist" is not protected by law; therefore anyone can call themselves a nutritionist.

Trans-unsaturated fatty acids (also called transfatty acids or trans-fat)— To make foods that will stay fresh on the shelf or to get a solid fat product, such as margarine, food manufacturers hydrogenate (add hydrogen) to polyunsaturated oils. This changes the double bond on the carbon atom from a cis configuration to a trans configuration, making the fatty acid saturated, and more of a health concern. For example, stick margarines are known to contain more trans fatty acids than liquid oils.

Resources

BOOKS

Bronner, Felix, ed. Nutritional and Clinical Management of Chronic Conditions and Diseases.Boca Raton, FL: CRC Press, 2005.

Eskin, N. A. Michael, and Tamir Snait. Dictionary of Nutraceuticals and Functional Foods (Functional Foods & Nutraceuticals Series). Boca Raton, FL: CRC Press, 2005.

Institute of Medicine, ed. Dietary Reference Intakes for Energy, Carbs, Fiber, Fat, Fatty Acids, Cholesterol, Protein, And Amino Acids. Washington: National Academies Press, 2005.

Lutz, Carroll A., and Karen Rutherford Przytulski Nutrition And Diet Therapy, 4th ed. Philadelphia, PA: F. A. Davis Company, 2006.

Temple, Norman J., Ph.D., et al. Nutritional Health: Strategies For Disease Prevention, 2nd ed. Totowa, NJ: Humana Press, 2005.

PERIODICALS

Cristina F. "Mediterranean diet health benefits may be due to a synergistic combination of phytochemicals and fatty-acids." British Medical Journal. 331 no. 7508 (2005): E366.

Westman, E.C., Yancy, W.S., Jr, Vernon, M.C. "Is a lowcarb, low-fat diet optimal?" Archives in Internal Medicine. 165 no. 9 (2005): 1071-72.

Price, S. "Understanding the importance to health of a balanced diet." Nursing Times. 101 no. 1 (2005): 30-31.

ORGANIZATIONS

American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, IL 60606-6995. (800) 877-1600. 〈http://www.eatright.org/〉.

American Heart Association National Center. 7272 Greenville Avenue, Dallas, Texas 75231. (800) AHAUSA1. 〈http://www.americanheart.org〉.

Food and Nutrition Information Center, Agricultural Research Service, USDA. National Agricultural Library, Room 105, 10301 Baltimore Avenue, Beltsville, MD 20705-2351. (301) 504-5719. Fax: (301) 504-6409. 〈http://www.nal.usda.gov/fnic/〉. [email protected].

International Food Information Council. 1100 Connecticut Avenue, NW, Suite 430, Washington, DC 20036. (202) 296-6540. Fax (202) 296-6547, 〈http://www.ific.org/〉. Email: [email protected]

U.S. Department of Agriculture (USDA), Agricultural Research Service. 5601 Sunnyside Avenue, Beltsville, Maryland 20705. "USDA Nutrient Database for Standard Reference, Release 18." Nutrient Data Laboratory Homepage 2005. 〈http://www.ars.usda.gov/ba/bhnrc/ndl〉. USDA home page 〈http://www.usda.gov/wps/portal/usdahome〉.

U.S. Department of Health and Human Services. 200 Independence Avenue, S.W., Washington, D.C. 20201. (202) 619-0257 or (877) 696-6775. 〈http://www.hhs.gov/〉.

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC). 1600 Clifton Rd, Atlanta, GA 30333. (800) CDC-INFO. 〈http://www.cdc.gov/〉. Email: [email protected]

U.S. Department of Health and Human Services, CDC, National Center for Health Statistics, 3311 Toledo Road, Hyattsville, MD, 20782.(866) 441-NCHS (6247). 〈http://www.cdc.gov/nchs/〉. Email: [email protected]

USDA Food and Nutrition Service. 3101 Park Center Drive, Alexandria, VA 22302 〈http://www.fns.usda.gov/fns/〉.