Protein derived from collagen and obtained by boiling bones, hooves, tendons etc in water. Commonly used in cookery. One third of gelatin consists of the amino acid glycine.

Gene

A discrete unit of DNA, carrying instructions for the proteins which make up the structures and functions of all living organisms. Genes ensure that the right proteins are made in the correct place, at the right time and in the appropriate amount. This strict control is incessary for the integrated and balanced functioning of complex biological structures and processes.

Genetic engineering

The isolation, cutting, joining and transfer of single or multiple genes between unrelated organisms. As a result, combinations of genes are produced that would never occur naturally. Natural species barriers can be circumvented, producing, for example, 'transgenic' tomatoes and strawberries containing the 'anti-freeze' gene from an arctic fish, to allow greater tolerance to frost. Transgenic so-called super salmon are being produced, with genes from the arctic sea flounder which allow the salmon to grow six times larger and ten times faster. Already on the market are soya beans containing a bacterial gene to confer pesticide resistance. An engineered insect virus possessing the scorpion toxin gene is being tested for spraying on crops as a broad-spectrum pesticide. Hundreds more projects are poised for commercialization.

Genetic engineering is said to promise disease- and pesticide- resistant crops and animals, crops which can grow in poor climatic and soil conditions, and tastier food with better nutritional value. Critics argue that transgenic crops and animals are experimental life forms with unpredictable long-term effects on human health and the environment. For instance a transgenic bacterium developed to overproduce the amino acid tryptophan for use in dietary supplements caused 37 deaths and more than a thousand cases of the rare blood disorder eosinophilia myalgia syndrome in 1989. Field trials in Scotland and Denmark using transgenic, herbicide-resistant oilseed rape have cross-pollinated with wild Brassica species, generating herbicide-resistant super-weeds. To allow consumers the opportunity to reject transgenic foods such as soya beans, used in some 60 per cent of processed food products, environmental organizations are campaigning for the segregation and labelling of such foods.

Genistein (see Soya products and Oestrogen)

Gentian

Herb

Gentian is known as the most important of all the European 'bitter' herbs. These are herbs containing bitter-tasting substances which act as digestive stimulants, stimulating gastric secretion and motility and promoting gastric tone, thus enabling food to be more easily digested. Gentian is active the moment that it is absorbed by the mucous membrane of the mouth. It may be beneficial in anorexia.

In the Chinese classification system, gentian is a 'cold bitter' which means that it is best applied in conditions of excessive vitality and avoided in any conditions involving coldness, such as depressed circulation or low metabolic rate, frequent urination or chronic respiratory congestion.