Lysine is involved in growth and bone development because it increases the absorption and deposition of calcium.  Lysine and another amino acid, methionine, forms carnitine.  Carnitine helps cells use fats for energy production.

By competing with arginine for absorption, lysine limits the reproduction of herpes virus and prevents herpes outbreaks (cold sores).  Lysine improves cardiovascular health by removing components of atherosclerotic plaques.  It has been shown to increase the diameter of vessels and improve blood flow.  Natural health practitioners for angina, poor circulation, herpes simplex, osteoporosis, improved athletic performance, convalescence and high triglyceride levels recommend lysine.

The biologically active form of lysine is L-lysine.  It is commonly found in capsules.  Lysine and arginine compete for absorption so supplements of these amino acids should be taken at different times.  It is often combined with vitamins and anti-viral agents for prevention of herpes outbreaks.  Take amino acid supplements at least 1/2 hour before or after a meal to maximize their absorption.  If you take an individual amino acid supplement for longer than one month, add an amino acid complex to the protocol to prevent the deficiency of other amino acids.

High arginine intake will lower lysine levels.  Individuals with kidney disease should use lysine cautiously.