Nutrition and Weight Control - How food relates to disease

Just as proper food is essential in the prevention of some diseases, it is helpful in the treatment of others. It also plays an important role in protecting and fortifying the general health of a patient while a specific illness is being treated.

The components of therapeutic diets are usually prescribed by the physician in charge, but some general principles will be presented here. Remember that diets designed to treat a given disease must supply the patient's basic nutritional requirements.


Special diet is a major treatment consideration in the case of peptic ulcer, whether located in the stomach (gastric) or in the small intestine (duodenal). A major aim of such a diet is the neutralizing of the acidity of gastric juices by the frequent intake of high protein foods such as milk and eggs. Foods which irritate an ulcer chemically, such as excessive sweets, spices, or salt, or mechanically, such as foods with sharp seeds or tough skins, and foods that are too hot or too cold, should be avoided. It is also advisable to eliminate gravies, coffee, strong tea, carbonated beverages, and alcohol, since all of these stimulate gastric secretion. Such a diet is called a bland diet. A soft diet is recommended for some forms of gastrointestinal distress and for those people who have difficulty chewing. It is often combined with the bland diet recommended for peptic ulcer patients to reduce the likelihood of irritation. See Ch. 11, Diseases of the Digestive System , for further information about ulcers.


As the section on diabetes mellitus indicates (see Ch. 15 ), the major objectives of the special diet are weight control, control of the abnormal carbohydrate metabolism, and as far as possible, psychological adjustment by the patient to his individual circumstances. To some extent, he must calculate his diet mathematically. First, his daily caloric needs have to be determined in terms of his activities.

If he is overweight or underweight, the total calories per pound of body weight will have to be adjusted downward or upward by about five calories per pound.

After his total daily caloric needs have been figured out, he can calculate the number of grams of carbohydrate, protein, and fat he should have each day: 58 percent of the calories should come from carbohydrates, 12 percent from protein, and 30 percent from fat. One-fifth of the total should be obtained at breakfast and the rest split between lunch and dinner. Snacks that are taken during the day should be subtracted equally from lunch and dinner.

It is important that meals and planned snacks be eaten regularly and that no food servings be added or omitted. Growing children from 1 to 20 years of age who have diabetes will require considerably more daily calories. A rough estimate is 1,000 calories for a one-year-old child and 100 additional calories for each year of age.

Salt-Free Diets

There are a number of chronic diseases which are treated in part by restricting the amount of sodium in the diet. These diseases, which are associated with fluid retention in the body, include congestive heart failure, certain types of kidney and liver diseases, and hypertension or high blood pressure.

The restriction of sodium intake helps to reduce or avoid the problem of fluid retention. The normal daily diet contains about seven or more grams of sodium, most of it in the form of sodium chloride or table salt. This amount is either inherent in the food or added during processing, cooking, or at mealtime. Half the weight of salt is sodium.

For people whose physical condition requires only a small restriction of the normal sodium intake, simply not salting food at the table is a sufficient reduction. They may decide to use a salt substitute, but before doing so should discuss the question with their physician.

A greater sodium restriction, for example, to no more than 5 grams a day, requires the avoidance of such high salt content foods as ham, bacon, crackers, catsup, and potato chips, as well as almost entirely eliminating salt in the preparation and serving of meals. Severe restriction—1 gram or less a day—involves special food selection and cooking procedures, as well as the use of distilled water if the local water has more than 20 milligrams of sodium per quart. In restricting sodium to this extent, it is important to make sure that protein and vitamins are not reduced below the minimum daily requirements. See “Sodium Restricted Diets.”

Other Diseases Requiring Special Diets

There are several other disorders in which diet is an important consideration: all chronic gastrointestinal disorders, such as ulcerative colitis, enteritis, gallbladder stones, and diverticulitis; a variety of hereditary disorders such as phenylketonuria and galactosemia; atherosclerosis, especially when it is associated with elevated blood levels of cholesterol or triglycerides or both; liver disease such as cirrhosis; many of the endocrine diseases; kidney stones; and sometimes certain neurological diseases such as epilepsy. Diet also plays a special role in convalescence from most illnesses and in post-surgical care. A modified fat diet and low fat diet are recommended for some diseases of the liver and gallbladder. A minimal residue diet is recommended for some digestive troubles and before and after gastrointestinal surgery.

Diet and Individual Differences

Most discussions about food and eating tend to suggest that all normal people have identical gastrointestinal and metabolic systems. This is simply not true. There are many individual differences that explain why one man's meat is another man's poison. A person's intolerance for a given food may be caused by a disorder, such as an allergy or an ulcer, and it is possible that many of these intolerances will ultimately be related to enzyme deficiencies or some other biochemical factor.

More subtle are the negative physical reactions to particular foods as a result of psychological conditioning. In most such cases, the choice is between avoiding the food that causes the discomfort or eating it and suffering the consequences. Of course, compulsive overeating can also cause or contribute to discomfort. Practically no one can eat unlimited quantities of anything without having gastrointestinal discomfort or dyspepsia .

The establishment of so-called daily minimum food requirements suggests that every day's intake should be carefully balanced. Although this is beneficial, it is by no means necessary. Freedom from such regimentation can certainly be enjoyed during a holiday, or a trip to another country, or on a prolonged visit to relatives with casual food habits.

Sometimes a change in diet is dictated by a cold or an upset stomach or diarrhea. Liquids containing carbohydrates, such as tea with sugar and light soups, should be emphasized in treating a cold, while at the same time solid food intake should be somewhat reduced. In the case of an upset stomach or diarrhea, the discomfort may be eased by not eating or drinking anything at all for a whole day. This form of treatment may be helpful for an adult, but since children with diarrhea can become dehydrated in a day or so, professional advice is indicated when cutting down liquid intake.

Diet and Disease Prevention

More and more, medical specialists agree that diet can be helpful in preventing various diseases. Consensus has become general that a diet low in cholesterol and saturated fats can help prevent cardiovascular disease caused by atherosclerosis. Among the foods that reduce total cholesterol levels are rice bran and oat bran. Other sources of the soluble fiber that decreases blood cholesterol include peas, lentils, barley, and pectin fruits like apples, oranges, pears, and prunes. Also recommended are skinless poultry and fish, lean meat, and low-fat dairy products.

Food-Borne Diseases

There are several ways in which food can be the cause of disease, most commonly when it becomes contaminated with a sufficient amount of harmful bacteria, bacterial toxin, viruses, or other poisonous substances. The gastrointestinal diseases typically accompanied by nausea, vomiting, diarrhea, or stomach cramps that are produced in this way are not, strictly speaking, caused by the foods themselves, and are therefore called food-borne diseases.

Most food-borne illnesses are caused by a toxin in food contaminated by staphylococcal or salmonella bacteria. In general, milk, milk products, raw shellfish, and meats are the foods most apt to be contaminated. This is most likely to happen when such foods are left standing at room temperature for too long between the time they are prepared and the time they are eaten. However, food can also become contaminated at many different points in time and at various stages of processing. Standards enforced by federal and local government agencies provide protection for the consumer for foods bought for the home as well as for use in restaurants, although whether the protection is adequate is a matter of dispute.

Food Storage

Food is best protected from contamination when it is stored below 40 degrees Fahrenheit or heated to 145 degrees or more. Cold slows bacterial growth; cooking kills it. Bacteria present in food can double in number every 15 minutes at room temperature.

All food stored in the refrigerator should be covered except ripe fruits and vegetables. Leftover foods cannot be kept indefinitely, nor can frozen foods be stored beyond a certain length of time. Specific information about these time periods for individual items is available from the Agricultural Extension Service in each state.

Commercially processed foods sold in the United States are under government control and generally are safe. However, any food can spoil or become contaminated at any point in time, and the consumer should not buy or serve food whose container (package or can) has been broken, cracked, or appears unusual.

Food Additives

From time to time, concern is expressed about one or another food additive as a hazard to health. Most of these additives are put into foods during processing in order to increase their nutritional value, or to improve their chemical or physical characteristics, such as taste and color. Perhaps as many as 2,000 different substances are used in this way in the United States. Some are natural products such as vanilla, others are chemicals derived from other foods, and a few, like artificial sweeteners, are synthetic. Other additives are referred to as indirect, since they are residues in the food from some stage of growing, processing, or packaging. Although additives are controlled and approved by agencies such as the federal Food and Drug Administration, they continue to be a cause of concern to many people.


The pesticides and fertilizers used in growing fruits and vegetables and the additives given to livestock may pose additional health hazards to humans. The National Academy of Sciences, for example, in 1988 estimated the national risk of cancer from pesticide use alone at as many as 20,000 cases a year.

Although it is not known how much is too much, it only makes sense to try and eliminate as much of the risk as possible. This is fairly easy to do. First of all, eat a wide variety of foods to help minimize your exposure to any one pesticide. Eat what's in season and what's grown locally or domestically. (The right season and less transportation mean less chemicals to ripen and preserve food; food and animals from abroad are subject to different health standards that are hard to regulate and check.) Wash all meat and produce carefully; many toxins are easily removed with soap and water. Peel any fruit or vegetable with a wax coating. (Although it is generally advisable to retain as much of the skin of produce as possible for higher vitamin content, wax coatings hold in toxic residues.) Trim produce.

You may also want to go further in reducing your chances of consumption of added toxins by buying organically grown and raised produce and meat. These foods are not widely available in all areas of the country, and they often cost quite a bit more than foods raised with chemicals, but many people not only feel safer eating these foods, but find them tastier as well. Home gardening without the use of chemical fertilizers and pesticides is another healthful option. Be sure to wash and trim carefully all organic or home-grown vegetables, however, to guard against ingestion of naturally occurring toxins such as fungus.

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