- Introduction -

WHY NUTRITION IS IMPORTANT

There is considerable truth in the adage 'You are what you eat'. The state of your body and how well it works depends to a large extent on how appropriately it is nourished. Malnutrition can be found in contemporary Western society and is not peculiar to developing countries.

Malnutrition occurs when a person's body is not adequately serviced by its food intake. Each individual's needs change under different circumstances. Moreover, the foods needed by an athlete, a grandmother, a growing boy, an office worker or a pregnant woman are not the same. Nutritional needs vary even from one office-worker to another, according to genetic make-up, level of activity, general state of health and environment.

Some groups of people who are at risk from nutrient deficiencies can be generally identified. These include those who are socio-economically disadvantaged; women during the reproductive years because of the added nutritional demands of menstruation and of pregnancy; the elderly; those who have a particular health problem, such as diabetes, faulty absorption of food or who are on certain medications; those with lifestyle problems such as cigarette smoking and alcohol abuse.

Diet and health

The most significant nutritionally related problems in industrialized nations are those health conditions that are the result of, or are made worse by, a diet that is not prudent:

Diet can increase the risk of heart disease in several ways. Eating foods that are high in saturated fat, low in polyunsaturated fat and high in cholesterol can raise the level of cholesterol in the blood. When the blood cholesterol level is increased the risk of coronary heart disease is increased. Another kind of blood fat (lipid) known as triglyceride can also be elevated and increase the risk of heart disease. Conversely, when relatively more fruits, vegetables and wholegrain cereals are eaten the blood fats are lower.

High blood pressure (hypertension) also increases the risk of heart disease, strokes and kidney failure. Blood pressure is higher when sodium intake is high, potassium intake (an element obtained mainly from plant foods) is low, alcohol intake is high and there is excess body weight. Eating too much, with consequent obesity, increases the risk of heart disease by increasing the work of the heart, increasing blood pressure, and increasing blood fats; obesity also increases the risk of diabetes. Nutritional factors can also alter the 'stickiness' of some blood cells, called platelets; this contributes to hardening of the arteries and may result in a blockage of the artery. Some polyunsaturated fish oils reduce the stickiness of platelets and may account for the rarity of heart disease amongst fish-eating communities, such as the Eskimos.

As far as tumours or cancers are concerned, a number of interesting food factors are emerging from research. A food intake low in fat and cholesterol, high in dietary fibre from wholegrain cereals, with plenty of vegetables and little alcohol seems protective against large bowel (colon and rectum) cancer. The reasons for this are not yet known. The same kind of dietary pattern may also reduce the risk of tumours of lung, breast, uterus, prostate and pancreas. There is little evidence so far to suggest that food additives are significant in the development of cancer.

Diabetes is a condition where the blood sugar (glucose) is too high because not enough insulin is produced by the pancreas for the body's needs. The glucose spills from the blood into the urine, leading to a large loss of water as urine; thirst then follows. Broadly there are two types of diabetes, one where it is necessary to administer insulin from the time of diagnosis and the other where it is not. Amongst Caucasians in industrialized nations two to three people in every 100 are affected. When non-Caucasians adopt the food habits of affluent society, they appear to be particularly susceptible to diabetes; from 15 to 40 per cent of Australians of Aboriginal or Pacific-Islander descent suffer from diabetes. Being overweight is a particularly important risk factor for developing the type of diabetes where administered insulin is not usually needed. A diet with a high intake of high-carbohydrate, high-dietary-fibre foods and a low intake of fat seems protective against the development of this type of diabetes.

Since most premature deaths in affluent societies result from atherosclerotic disease of blood vessels (vascular disease), and from lung, breast and large bowel cancer, there is great potential for dietary change to increase life expectancy and, indeed, to reduce morbidity and chronic illness.

-  Diet and health