Histidine is a semi-essential amino acid - adults generally produce adequate amounts, but in infancy it is lacking and therefore essential. It is one of the basic amino acids due to its aromatic nitrogen-heterocyclic imidazole side chain.
Histidine is found abundantly in haemoglobin, and comes from dairy, meat, poultry and fish sources. It is a metalloprotein that can bind and transport several metals, including copper, iron, and zinc, and it is also a precursor of histamine, a compound released by immune system cells during allergic reactions, and responsible for a wide range of physiological processes.
Histidine is needed for growth and for the repair of tissue, as well as the maintenance of the myelin sheaths that act as protectors for nerve cells. Because of histidine's zinc-binding properties, the myelin is compacted and provides more nerve-insulating protection. One study showed that by increasing absorption of zinc, histidine stimulated growth and thickened the growth plate in bone.
Zinc is a factor in insulin sensitivity, prostaglandin synthesis, and immune function. It helps remove heavy metals from the body, and protect the body from damage caused by radiation. It is required for the manufacture of red and white blood cells, and supports the activity of suppressor T cells.
Histidine is also beneficial in the following ways;
In the stomach, histidine is helpful in producing gastric juices, and therefore reduces indigestion
It is an important mechanism in clotting factors and can minimise internal bleeding from microtrauma
Histidine is used as a treatment for sufferers of rheumatoid arthritis, since it has been shown that in these patients, histidine levels are low
Older men who experience a decrease in sexual response may be helped by histidine supplementation, as may men suffering from impotence, as histidine has a vasodilating effect, thus making blood flow to the sex organs easier
In the heart, the ability of histidine to act as an electron donor results in improved heart function during heart attack and cardiac procedures such as angioplasty, heart bypasses and heart transplants.