What is it? Lysine is an essential amino acid that plays many important roles in the body, including protein synthesis and immune function. It is used to fight the symptoms of cold sores, and is commonly paired with Vitamin C during winter months as to prevent development of the common cold!
What does it do? Being an essential amino acid, Lysine cannot be produced by the body itself and therefore must be consumed via diet or supplementation. The studies assessing Lysine have examined its role as a suppressor of the herpes complex virus (mainly cold-sores); its ability to function as a precursor to the amino acid Carnitine (useful for fat-burning); and increasing the intestinal absorption of calcium (also eliminating its excretion by the kidney) suggesting that it might be helpful in osteoporosis.
It is commonly found in all animal products and some lentils, however its content in vegetables and fruits (excluding Avocado) is very low. So, it is quite common that a vegan/vegetarian diet would lead to deficiencies (especially if lentils are not a major staple in the diet). Lysine and Arginine use the same metabolic pathway, so excessive use of Arginine (including its precursors like ornithine and citruline) has also been reported to lead to deficiencies in Lysine. This is usually represented in developing a cold-sore or a general immune decline (depending on the severity of deficiency).
From personal experience, greater use of citruline as a vasodilator (6g or more) in pre-workouts have led to symptoms of cold-sores, however same cannot be said of Arginine (excess of 10g at night for a boost in growth hormone production has not resulted in side-effects associated with Lysine deficiency). This only occurs if you are predisposed to cold-sores, if you’ve never had one, chances are greater use of citruline will not lead to sudden development.
Who Should take it? Anyone who wants to keep on top of their immune system, especially during the winter season, anyone who’s at risk of osteoporosis, and those who commonly develop cold-sores. If following a diet low in Lysine (no animal products or lentils) it is recommended to consume Lysine with meal(s).
How do I take it? 1 to 3 grams daily seems to be the standard dosage for general immunity and symptom prevention. Higher dosages of 5g per day are needed to combat actual cold-sore breakouts.