Constipation often results from a diet low in fibre or fluid, or from generally poor eating habits. Prunes are often recommended to counteract it as they contain a substance which prompts bowel motion. Pregnant women and the elderly are particularly susceptible to constipation or it can be a side-effect of iron tablets or certain drugs. To relieve it, eat more unprocessed bran, potatoes and their skins, fresh fruits and raw vegetables, drink more water and fruit juices. However, if the problem persists, consult your doctor.

Diarrhoea occurs as a result of infection, defective enzyme production (lactose intolerance, for example), organic disease or a side effect of certain drugs such as antibiotics. It can also be a symptom of niacin (a B group vitamin) deficiency or part of a sunstroke reaction. Take plenty of fluid to guard against dehydration. Extra dietary potassium, sodium and chlorides may be needed to replace losses. if your diarrhoea persists without obvious cause, consult your doctor.  If you are taking the pill you should use an additional form of protection.

Malnutrition is not normally found in Western societies, except occasionally among the elderly, and among vegetarians who are not careful to account for the lack of animal animal in their diet. In some Eastern and African countries, long-term malnutrition is a common problem due to carbohydrate and particularly to overall food energy deficiency. There are 2 forms: marasmus results from a chronic lack of protein and carbohydrate in the diet; kwashiorkor results from a diet in which the carbohydrate intake may be sufficient but a simultaneous lack of protein stunts growth.