Once you have a herpes virus in your body, it is with you for life. After an initial infection, which can be mild or severe, it will go dormant in the body. If the immune system becomes weakened, from another illness or from stress for example, the virus can reactivate and cause a flare up. One example is shingles which happens when the varicella zoster virus, which is herpes virus 3, reactivates and causes a painful rash. The body uses the amino acid lysine to keep herpes viruses dormant. Several factors can influence the amount of lysine that is available in the body for this purpose. Yeast produces a metabolite that deprives the body of lysine.
Also, our diet can matter. Lysine competes in the body with arginine, another amino acid. Depending on which sources of protein we eat, we may be taking in more lysine or more arginine. Eating a lot of arginine can actually cause a flare up of a herpes virus. To keep the viruses dormant, ideally we should consume a ration of 2:1 lysine to arginine or better.
This is a list of how much lysine and arginine various foods contain:
Notice that generally sources of animal protein, dairy and meat, have more lysine to arginine, and plant sources of protein (grains, nuts, beans, etc) tend to have lower amounts of lysine to arginine or even more arginine than lysine (and PLEASE don't eat margarine!!). The ratio isn't the only significant number here though, the total number of mgs matters. For example, 246 grams of Ricotta cheese has 3290 mg of lysine to 1550 mg of arginine, the difference is large and it is an excellent source of lysine despite the large amount of arginine that it also contains. 3 grams of garlic contains 8 mgs of lysine and 19 mgs of arginine, for a ratio that favors arginine, but the actual amount of arginine above the lysine is so low that it won't cause problems. I hope that makes sense.
You can also use supplements to increase your intake of lysine relative to arginine. Many sites and groups recommend around 1000 mg 3 x a day of lysine during an outbreak, but differ on how much to take to prevent outbreaks. That would probably depend somewhat on your dietary intake of lysine and arginine, the amount of yeast you have in your body, as well as your own individual needs. Some people take high doses of arginine for mitochondrial support or when detoxing oxalates, so these may be times when a supplement is particularly helpful.
About.com lists some of the common herbal supplements used to fight herpes as well.
