Lisina

Lisina, known as lisina in several languages, is an essential amino acid in humans and many other organisms. It is one of the 20 standard amino acids used to build proteins, and the body cannot synthesize it in sufficient amounts, so it must be obtained from the diet. Lisina has a basic side chain, giving it a positive charge at physiological pH and influencing protein structure and interactions.

Biological role: Lisina is required for protein synthesis, growth, and tissue repair. It participates in the production of enzymes, hormones, and antibodies, and contributes to collagen formation and bone health. It is a precursor in the biosynthesis of carnitine, a molecule involved in fatty acid transport into mitochondria, and may influence calcium absorption and immune function.

Dietary sources and intake: Rich sources include meat, fish, eggs, and dairy products, as well as plant foods such as legumes, soy, and quinoa. Cereals and grains tend to be relatively low in lisina, so balanced diets often combine complementary proteins to ensure adequate intake. Much of the lisina used in food and feed is produced commercially by microbial fermentation.

Deficiency and supplementation: Lisina deficiency is uncommon in developed countries but can occur with very restrictive diets, leading to fatigue, slowed growth in children, anemia, and impaired immune responses. Supplements are used to support protein synthesis and recovery, and, in some contexts, to help manage herpes simplex virus infections; evidence for the latter is mixed. High doses can cause gastrointestinal upset and may interact with certain medications, so intake should follow dietary guidelines and medical advice.