A dietary supplement extracted from pineapples, used as an aid to protein digestion. It may be combined with papain, a similar enzyme extracted from papaya fruit. Bromelain can also be used in cookery as a meat tenderizer.

Availability: widely available in health food shops.

Brown fat (see Adipose tissue)

Buckwheat

Buckwheat is not a variety of wheat and is not related to wheat. It is the seed of a herbaceous plant related to dock and rhubarb, and is a rich source of the flavonoid rutin. A Russian porridge-like cooked cereal called kasha is made from roasted buckwheat. Buckwheat is free of gluten, and can be cooked like rice. It is also ground into flour.

Bulghur wheat

Wheat grains which have been cracked between rollers and then hulled, steamed and roasted. Bulghar wheat swells when water is added and can be combined with chopped raw vegetables and salad dressing to make a cold dish which is high in complex carbohydrates.

Bulimia nervosa

An eating disorder involving compulsive binge eating, usually in secret, often accompanied by self-induced vomiting and laxative abuse to control weight. As with anorexia nervosa, there is a morbid fear of becoming fat.

Butyric acid

A short-chain fatty acid found in butter, which gives butter its characteristic smell and taste. It is also formed during the colonic fermentation of dietary fibre and is an important energy source for the colonic mucosa (mucous membrane), accounting for the major part of its energy needs even in the presence of glucose. This makes it an important nutrient for growth and repair and nutritional therapists may accordingly administer it in supplement form for this purpose. Individuals who have been on a diet low in fibre may develop deficiencies of this nutrient.

Availability: From nutritional therapists.