L-Allothreonine (L-allo-Threonine) is an essential amino acid in humans. L-Allothreonine is abundant in human plasma, particularly in newborns. Severe deficiency of threonine causes neurological dysfunction and lameness in experimental animals. L-Allothreonine is an immunostimulant which promotes the growth of thymus gland. L-Allothreonine also can probably promote cell immune defense function. L-Allothreonine is highly concentrated in meat products, cottage cheese, and wheat germ.