Threonine, an essential amino acid, is not manufactured by the body and must be acquired from food. It is an important constituent in many body proteins and is necessary for the formation of tooth enamel protein, collagen and elastin. It is a precursor to the amino acids glycine and serine. It acts as a lipotropic in controlling fat build-up in the liver.
One researcher considers Threonine, along with B vitamins, magnesium, ascorbic acid, iodine, potassium, tryptophan, lysine, inositol and glutamic acid, as being essential in the treatment and prevention of mental illness. Another states that Threonine “is very useful in indigestion and intestinal malfunctions and prevents excessive liver fat. Nutrients are more readily absorbed when threonine is present.” Preliminary studies in patients with the degenerative neuromuscular disease ALS showed definite symptom improvement with L-threonine supplements. Since there is no other treatment for this disease, it may prove useful in allowing these people a better quality of lifestyle.
There are good levels of threonine in most meats, dairy foods and eggs and moderate levels in wheat germ, many nuts, beans and seeds and some vegetables. Threonine is an immune stimulant-it promotes thymus growth and activity. L-threonine deficiency in rats has been associated with weakened cellular response and antibody formation. In humans, deficiency results in irritability and generally difficult personality, according to one researcher. The range of human requirements is stated to be between 103 milligrams and 500 milligrams daily .