In the 2006 edition of "Modern Nutrition in Health Disease," University of Vermont Professor Dwight E. Matthews, Ph.D., explains that lysine constitutes one of the nine essential amino acids that humans must obtain from their diets in order to survive. In addition to its role in normal growth and metabolism, lysine may suppress the reproduction of the herpes simplex virus that causes fever blisters, reducing the number and severity of outbreaks.
Function
In the 2007 edition of "Integrative Medicine," complementary and alternative medicine specialist, David Rakel, M.D., explains that lysine works mainly by opposing the effects of another amino acid, arginine. The herpes simplex virus requires arginine to reproduce, and arginine may even play a role in stimulating the virus to reproduce, according to Dr. Rakel. Because arginine, like lysine, is an essential amino acid, it cannot be safely eliminated from the diet. So, Dr. Rakel says, strategies have generally focused on providing increased amounts of lysine.
Sources
Foods rich in lysine include red meat, pork, poultry, cheese, fish, nuts, eggs, soybeans, brewer's yeast and legumes such as lentils, according to the University of Maryland Medical Center. Supplemental lysine may also be purchased in tablets, capsules, creams or liquid form. Those who undertake a lysine-rich diet should do so in the context of a balanced diet that also includes fruits, vegetables and grains. Those who consider taking lysine supplements should talk to their doctors before beginning treatment.
Doses
The amount of lysine required to treat or prevent fever blisters far exceeds the requirements for normal growth and metabolism. The University of Maryland Medical Center recommends supplement doses of 3g per day for the prevention of fever blisters and 3 to 9 g per day for the treatment of an active outbreak. Dr. Rakel recommends starting conservatively by increasing portions of lysine-rich foods before turning to supplements.
Effectiveness
Dr. Rakel describes a study of 52 people with a history of fever blisters randomized to receive either 1 g of lysine or a placebo three times each day. At the end of six months, 74 percent of the patients who received lysine reported that it was effective or very effective in treating or preventing fever blisters, compared with 28 percent of patients who received the placebo. In addition, those taking lysine averaged 3.1 fever blister outbreaks, compared with 4.2 outbreaks for people who took the placebo. But Dr. Rakel also cautions that other studies have failed to find that lysine has any effect on fever blister outbreaks.
Safety
The University of Maryland Medical Center says studies demonstrate an increased risk of gallstone formation and elevated levels of cholesterol among animals treated with high doses of lysine. Lysine supplements may not be safe for people with kidney, liver or inherited metabolic disorders involving amino acid metabolism, as well as infants and women who are pregnant or nursing. Lysine does not replace conventional medical treatments for fever blisters. A registered dietitian can provide ideas on how to increase lysine intake from foods. As with any other dietary supplement, those who consider taking lysine in supplement form should consult their doctors.
References
- "Integrative Medicine"; David Rakel, M.D.; 2007
- University of Maryland Medical Center: Lysine
- "Modern Nutrition in Health and Disease"; Maurice E. Shils, M.D. et al.; 2005
