Lysine is an essential amino acid, meaning that it is a building block of protein — needed to maintain our health — that does not occur naturally in the body. The only way to ensure that you have enough lysine to stay healthy is to ingest it through foods or supplements. Lysine is found in proteins, including meats, eggs, nuts, lentils, soybeans and cheeses, particularly parmesan cheese. It is credited with helping our bodies absorb calcium, repair and maintain connective tissue and is also used as a natural treatment for cold sores. Lysine deficiency can cause nausea, fatigue, anemia, slow growth, agitation and reproductive disorders.

Peanut Oil

Peanut oil not only contains high levels of lysine, it is also cholesterol free, free of trans fat and low in saturated fats, making it one of the healthiest cooking oils on the shelf. In addition to its health benefits, one unique characteristic of peanut oil is that it does not absorb the flavors of the food it is cooking. According to The Peanut Institute, this allows you to use the oil to fry more than one item at a time without crossover tastes.

Soybean Oil

You may know it as vegetable oil, but that amber liquid you add to your frying pan and favorite baked products is actually soybean oil. Like the beans it’s extracted from, this oil contains lysine. Soybean oil is also a core component of margarine and many salad dressings.

Cod Liver Oil

Codfish is high in lysine. Accordingly, so is codfish-extracted cod liver oil. This well-known naturopathic treatment is used by many to ease the symptoms of arthritis, thanks in part to lysine’s role in repairing and maintaining the health of connective tissue. The oil, which also contains high levels of vitamin D, is available at health food stores in liquid or capsule forms.

Parmesan Oil

Parmesan oil, also know as parmesan-infused olive oil, is made by heating olive oil and then adding either shaved parmesan cheese or the rinds of the cheese. The mixture is left to sit for about six months, then the cheese is strained out. In addition to acquiring a parmesan taste, the olive oil absorbs the nutrients — including the lysine — from the cheese.