The Institute of Medicine says that lysine is one of nine essential protein-precursors called amino acids that a person must obtain from food in order to maintain good health. In addition to its nutritional functions, lysine may modestly diminish the incidence of cold sores among those infected with the oral form of the herpes simplex virus. Lysine, however, does not replace conventional medical treatments for cold sore prevention.
Function
In the 2007 edition of "Integrative Medicine," University of Wisconsin Professor, David Rakel, M.D., explains that lysine exerts its cold-sore preventative effects mainly by antagonizing another amino acid, arginine. The herpes simplex virus relies on arginine to produce proteins critical to its replication. In addition, Dr. Rakel says, the presence of arginine appears to cue the herpes simplex virus to activate in cells where it was previously dormant. Because arginine, like lysine, is an essential amino acid, strategies to prevent cold sores through the modulation of amino acids have generally focused on increasing the amount of lysine, rather than decreasing the amount of arginine.
Dose
Lysine supplements come in tablet, powder, cream and liquid form. The University of Maryland Medical Center says the standard dose of lysine to prevent cold sores is 1,000 mg three times per day. Taking higher doses of up to 3,000 mg three times per day at the first sign of an outbreak may keep the outbreak from becoming worse.
Effectiveness
Dr. Rakel says that studies of the effectiveness of lysine at preventing cold sores have had mixed results. Some studies show a modest positive effect, while others show no benefit at all. In addition, the studies seem to suffer from methodology issues, according to Rakel. For example, critics of the positive studies note that they involved only a small number of people, suggesting that the results may not hold true for the rest of the population. Critics of the studies that failed to find an effect say that 1,000 mg doses simply weren't high enough.
Safety
The Institute of Medicine says that supplementing any one amino acid can disrupt protein synthesis by altering the balance between all of the other amino acids. In addition, the Institute notes, doctors and scientists don't know enough to define the safe maximum dose of any one amino acid, although there is ample evidence that very high amounts of protein can lead to health problems such as kidney disease. Dr. Rakel says that people with kidney or liver disease and women who are pregnant or nursing should probably steer clear of lysine.
Considerations
People who consider taking lysine for the prevention of cold sores should discuss this decision with their doctors first. Lysine is also found in many foods --- particularly animal-based foods such as red meat, pork, poultry, fish, cheese and other dairy products and eggs. Dr. Rakel recommends consuming additional servings of lysine-rich foods before turning to supplements. A registered dietitian can provide specific suggestions about how to incorporate lysine-rich foods into a healthy, balanced diet.
References
- "Integrative Medicine"; David Rakel, M.D.; 2007
- University of Maryland Medical Center: Lysine
- National Academies Press: Institute of Medicine: Dietary Reference Intakes: Protein and Amino Acids
