Lysine

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

Lysine has many functions in the body because it is incorporated into many proteins, which are used by the body for a variety of purposes. Lysine interferes with replication of herpes viruses and is therefore often prescribed by 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.2

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

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

Rating Health Concerns
3Stars Cold sores (recurrence prevention)
2Stars Genital Herpes
1Star Shingles
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? Most people, including vegans (vegetarians who also avoid dairy and eggs), consume adequate amounts of lysine. However, vegans whose diets contain large amounts of grains and only minimal amounts of beans could become deficient in 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.

How much is usually taken? Most people do not require lysine supplementation. Doctors often suggest that people with recurrent herpes simplex infections take 1,000–3,000 mg of lysine per day.

Are there any side effects or interactions? In animals, high amounts of lysine have been linked to increased risk of gallstones3 and elevated cholesterol.4 At supplemental amounts, 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.5

Lysine supplementation increases the absorption of calcium and may reduce its excretion.6 As a result, some researchers believe that lysine may eventually be shown to have a role in the prevention and treatment of osteoporosis.7

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.

References:

1. Civitelli R, Villareal DT, Agneusdei D, et al. Dietary L-lysine and calcium metabolism in humans. Nutrition 1992;8:400–4.

2. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr 1997;16:7–21 [review].

3. Kritchevsky D, Weber MM, Klurfeld DM. Gallstone formation in hamsters: influence of specific amino acids. Nutr Rep Int 1984;29:117.

4. Leszczynski DE, Kummerow FA. Excess dietary lysine induces hypercholesterolemia in chickens. Experientia 1982;38:266–7.

5. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr 1997;16:7–21 [review].

6. Civitelli R, Villareal DT, Agnusdei D, et al. Dietary L-lysine and calcium metabolism in humans. Nutrition 1992;8:400–5.

7. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr 1997;16:7–21 [review].