Glycerine or glycerol forms about 5-10 per cent by weight of most triglycerides (fats). Fats are composed of a glycerol 'backbone' attached to three fatty acid molecules. Glycerol is also a component of lecithin.

Glycine (also see Detoxification)

Amino acid

Glycine is the simplest of the amino acids, and can be synthesized by the body from the amino acids serine or threonine. Like taurine and GABA it acts as a major inhibitory neurotransmitter and is highly concentrated in the brain, particularly in the areas that are involved in Parkinson's disease. Glycine is rapidly broken down in the body.

Glycine is a glycogenic amino acid - it is capable of building up glycogen, or stored carbohydrate. It assists in the manufacture of DNA, glycerol and phospholipids, cholesterol conjugates, collagen and glutathione. Glycine can be converted to pyruvate and thus act as fuel for energy production. It is essential for glycine conjugation - one of the key liver detoxification pathways. Glycine is a potent stimulator for the secretion of glucagon, which raises blood sugar levels, and when supplemented in large amounts can also raise growth hormone levels. Low glycine levels are often found in manic-depressive and epileptic patients, who may respond to supplementation since glycine is an inhibitory neurotransmitter.

Glycine supplementation can increase the clearance of uric acid by the kidneys, and may be a useful aid to the treatment of gout. It is essential for wound healing, and may be added, along with zinc, to ointments and creams for this purpose. Glycine, in combination with alanine and glutamic acid, has been used to improve the symptoms of benign prostate hypertrophy (prostate enlargement).

One third of the protein gelatin consists of glycine. Gelatin is therefore a cheap and useful source of this amino acid.

Glycogen

The storage form of carbohydrate within the body. Glycogen is mostly stored in the liver (where it is used to maintain the blood sugar level between meals) and in the muscle cells, (where it is used as a source of energy). Higher amounts of muscle glycogen can be induced by feeding a high-carbohydrate diet after heavy exercise which depletes muscle glycogen stores.

Glycolysis (see Energy production)

Glycoproteins

Proteins attached to oligosaccharides. They form part of many substances and components of the human body, including cell walls, collagen, bone matrix, mucous secretions, hormones, enzymes and nutrient transport mechanisms.

Goitrogens

Naturally-occurring substances found in some foods, which in large amounts can inhibit the body's production of thyroid hormone. Some of these foods are: cabbage, peanuts and soya products.