Nutritional deficiencies are rare in Britain although some cases of anaemia due to deficiencies of iron, vitamin B12 or folic acid are reported. Without sufficient iron the body cannot make enough haemoglobin. Vitamin B12 and folate deficiencies give rise to kinds of anaemia in which there are large blood cells and a low concentration of haemoglobin. Pernicious anaemia is associated with lack of a substance in the stomach which allows vitamin B12 to be absorbed. Women have higher requirements for these nutrients, particularly iron, than men owing to menstrual blood losses. Should dietary intake fall below the requirement it is feasible to supplement with iron tablets.
Some cases of scurvy are still found, underlining the need for a regular intake of vitamin C and fresh food. Vitamin D deficiency still exists in some city children, elderly people and in some Asian communities whose dietary and social customs restrict access to vitamin D rich foods and sunlight.
Some people are born without certain enzymes to digest specific nutrients which then have to be omitted from the diet. Lactose cannot be digested by some babies who have to be fed with special lactosefree milk. The ability to digest lactose in adulthood only remains in European people. Many other races lose their lactose enzyme as they age and they cannot eat dairy produce without ill effect. Newborn babies have their blood tested to check that they have the enzymes which allow the digestion of amino acids in milk.
Coeliac disease occurs most often in childhood and may be due to a type of allergic reaction to gluten in the gut. Gluten is a protein in wheat and rye flour so bread and many manufactured products have to be eliminated. Some people suspect that certain foods cause them to have allergic reactions such as rashes, irritations, sickness, diarrhoea, headaches or swellings. This can be tested by a starvation period of a few days followed by the gradual rcintroduction of test foods in order to see whether the symptom is produced.
Diabetes is a condition where blood glucose levels cannot be closely regulated within the narrow range necessary for health, owing to an insufficiency of insulin production. Insulin is secreted by certain cells in the pancreas which in some people are absent or malfunctioning. Diabetes which develops in childhood is often more severe than that in adult life, the latterbeing commonly associated with overweight. Treatment may be by insulin injections, or oral insulin plus possibly dietary restrictions. A system of carbohydrate unit counting is recommended for diabetic diets with weight reduction where necessary.
Some diabetic foods use artificial sweeteners to encourage slimming, others use sorbitol, a derivative of glucose, which is sweet but does not cause blood glucose to rise and does give dietary energy.
Gout is a form of arthritis which causes painful joints owing to the accumulation of uric acid which has not been excreted. The disease tends to run in families, is more common in men than in women and is associated with an affluent way of life. Drug treatments can help relieve pain but dietary measures can also help. Food should be eaten in small, regular amounts and liver, kidneys, sardines, anchovies, fish roes, meat extracts and alcohol should be avoided.
Many things we do in our modern life are known to increase the risk of cancer. Probably at least eighty per cent of human cancers are environmental in origin. The extent to which cancers of the gut or organs are induced by food or chemicals is difficult to test. Stomach cancer appears to be related to salt intake. Many cancer producing agents (carcinogens) occur in food naturally. They can be produced by processing, for example smoking, or occur in preservatives. Such occurrences are tested and monitored. Some food colourings are carcinogenic and many countries are trying to agree on lists of permitted colourings. Nevertheless there is no room for complacency as further research in this area is needed.
Cancer of the lower intestine is increasing in prevalance along with uncomfortable diseases of the bowel like diverticulitis. A new theory suggests that our modern diet is so low in roughage that digestive products form a very small, hard bolus (food processed in the stomach), which needs strong contractions to move it along the gut. This can cause damage to the gut wall and the slow passage of food encourages the growth of undesirable bacteria. These microorganisms make carcinogenic compounds which accumulate and irritate the damaged walls. Roughage, particularly cereal fibre like bran, has the property of holding water, increasing the bulk of the faeces and allowing easier, faster passage of stools. Increasing dietary fibre can be achieved by changing to wholemeal bread, pastry and biscuits, or supplementing ordinary foods with bran. This treatment is being tried by some doctors for patients who already have intestinal disorders. It is a safer method of preventing constipation than using laxatives. Health claims for fibre preventing obesity, vascular disorders and coronary heart disease are less well accepted. High fibre intakes can reduce the absorption of some nutrients so this should only be practical if the diet is nutritionally sufficient.