A family of substances: caffeine, theophylline and theobromine, which are derived from xanthine, are found in tea, coffee, cola and chocolate, and have pronounced physiological effects on the body.

Caffeine stimulates the central nervous system, while theophylline and theobromine stimulate the heart. Theophylline is also available as an anti-asthma drug.

There is some evidence that the consumption of methylxanthines is associated with breast lumps and cysts. Women who have ceased consuming methylxanthine-containing foods have experienced a reversal of this condition.

Micronutrients

Substances required in the diet in amounts measurable in milligrams or smaller units. These substances include vitamins, minerals and trace elements.

Milk

The natural food of infants, milk is a good source of protein, fatty acids, vitamins and some minerals. However cow's (and other animals') milk is not a suitable substitute for human breast milk before weaning, and special formula feeds must be fed to young babies. Some authorities believe that cow's milk should not be fed to infants below one year of age because an immature digestive system may be unable to digest it sufficiently. The improper digestion of any food can lead to the development of an allergy.

Other authorities believe that cow's milk and dairy produce are not suitable foods for children or adults because other mammals do not continue to consume milk after weaning. A large percentage of the world's population is lactose-intolerant - they cannot digest the sugar lactose found in milk, and develop diarrhoea if they try to drink it.

Cow's milk allergy is one of the most common food intolerances and can be responsible for a wide range of symptoms from migraine to sinusitis, eczema and irritable bowel syndrome. The promotion of milk drinking by workers in the public health sector is intended to ensure that those who know and understand little about healthy eating and who may eat and may feed their children an otherwise poor diet, will at least be assured of a good range of vital nutrients if they consume milk daily.

Those eating a well-balanced wholefood diet rich in nuts, seeds, wholegrains and leafy vegetables do not normally need to consume milk and dairy produce in order to obtain sufficient calcium.

Mineral water

Natural spring water containing small amounts of dissolved minerals such as iron sulphide and sodium bicarbonate.

Miso

A Japanese food made from soya beans (and sometimes grains such as rice or barley) and sea salt fermented for 18 months to 3 years with the koji culture. Koji produces enzymes which break down the starches, oils and protein of the beans into easily assimilated simple sugars, fatty acids and amino acids. The fermentation process is also said to produce vitamin B12, but analysts have found only 0-0.02 mcg B12 in miso samples.

Miso is said to be excellent for people with weak digestive systems and, for those who have been taking antibiotics, to help repopulate the gut with friendly bacteria.

Miso is sold as a dark brown paste which should be diluted with hot water and used as soup or stock. It has a pleasant savoury flavour similar to stock made from yeast extract. Traditional miso soup consists of miso dissolved in hot water and flavoured with spring onion (scallion) and a little wakame seaweed. Instant miso soup can be bought in packets in powdered form.

Availability: from health food shops and macrobiotic suppliers.