What does it do? Lysine is an essential amino acid needed for growth and to help maintain nitrogen balance in the body. Essential amino acids cannot be made in the body and must be supplied by the diet or supplements. Lysine appears to help the body absorb and conserve calcium.¹ Linus Pauling believed that lysine helps maintain healthy blood vessels, an idea based on biochemistry and results from three people with angina pectoris who responded to lysine supplementation.^{2 3}

Lysine has many functions in the body because it is incorporated into many proteins, each of which is used by the body for a variety of purposes. Lysine interferes with replication of herpes viruses and is therefore often prescribed by nutritionally oriented doctors to people with cold sores or genital herpes. A review of the research trials investigating the effects of lysine on people with cold sores shows that most though not all trials support the use of lysine.⁴

Where is it found? Brewer’s yeast, legumes, dairy, wheat germ, fish, and meat all contain significant amounts of lysine.

Lysine has been used in connection with the following condition (refer to the individual health concern for complete information):

Who is likely to be deficient? Most people, including vegans (vegetarians who also avoid dairy and eggs), consume adequate amounts of lysine. Athletes involved in frequent vigorous exercise have increased need for essential amino acids, although most diets meet these increased needs. The essential amino acid requirements of burn patients may exceed the amount of lysine in the diet.

Are there any side effects or interactions? In animals, high doses of lysine have been linked to increased risk of gallstones⁵ and elevated cholesterol.⁶ At supplemental doses, no consistent problems have been reported in humans, though abdominal cramps and transient diarrhea have occasionally been reported at very high (15-40 grams per day) intakes.⁷

Lysine supplementation increases the absorption of calcium and may reduce its excretion.⁸ As a result, some researchers believe that lysine may eventually be shown to have a role in the prevention and treatment of osteoporosis.⁹

Lysine works with other essential amino acids to maintain growth, lean body mass, and the body’s store of nitrogen.

At the time of writing, there were no well-known drug interactions with lysine.

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References:

1. Civitelli R, Villareal DT, Agneusdei D, et al. Dietary L-lysine and calcium metabolism in humans. Nutrition 1992;8:400–404.
2. Pauling L. Case report: Lysine/ascorbate-related amelioration of angina pectoris. J Orthomol Med 1991;6:144–46.
3. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutri 1997;16:7–21 [review].
4. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutri 1997;16:7–21 [review].
5. Kritchevsky D, Weber MM, Klurfeld DM. Gallstone formation in hamsters: influence of specific amino acids. Nutr Rep Internat 1984;29:117.
6. Leszczynski DE, Kummerow FA. Excess dietary lysine induces hypercholesterolemia in chickens. Experientia 1982;38:266–67.
7. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutri 1997;16:7–21 [review].
8. Civitelli R, Villareal DT, Agnusdei D, et al. Dietary L-lysine and calcium metabolism in humans. Nutrition 1992;8:400–405.
9. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr 1997;16:7–21 [review].