The Amino Acid L-Lysine

Parmesan cheese has l-lysine.
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Carbohydrates, fats and proteins -- each nutrient has smaller building blocks. In the case of proteins, amino acids are the smaller parts of the whole. One such amino acid is l-lysine. Your body doesn't make lysine on its own, so you've got to take in enough from the foods you eat. If you don't, you can experience some unpleasant symptoms.

Essential Amino Acids

Amino acids can be divided up into three categories: essential, non-essential and conditional. Your body can make the non-essential amino acids all on its own, so you don't need them from your diet. Conditional amino acids are those your body needs under special instances, such as illness or stress. Essential amino acids are those you have to get from your diet because the body cannot synthesize them. These include lysine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan and valine.

Food Sources

You'll need about 12 milligrams of lysine per kilogram of bodyweight per day to meet your recommended intake, according to the University of Maryland Medical Center. Lucky for you, a variety of foods contain lysine, including red meat, pork and poultry. Fish such as cod and sardines also contain lysine as do nuts, eggs, soybeans, spirulina and fenugreek salad. Beans, legumes and dairy products also have lysine, which means if you eat a diet that features a variety of foods, you'll likely take in enough lysine.


Lysine's functions have a lot to do with healthy growth. For example, lysine is responsible for making collagen, a substance present in your bones, skin, tendons and cartilage. Lysine also helps your body make carnitine, a substance that helps your body use fats for energy and reduces your cholesterol. If you don't get enough lysine, you can experience symptoms such as unexplained fatigue, nausea, dizziness, appetite loss, bloodshot eyes, anemia and slow growth. Athletes and vegans who don't eat beans may have difficulty getting enough lysine in their diets.

Lysine as a Supplement

You can get an extra lysine boost by taking a supplement. Though not everyone needs a supplement, if you have a history of the herpes simplex virus, lysine may help to prevent cold sores from occurring. You can take about 1,000 milligrams of lysine per day to prevent a breakout, according to the University of Maryland Medical Center. Lysine may not be so good at defending against current cold sore breakouts, however. The amino acid also may be able to help prevent bone loss due to osteoporosis, a bone-wasting condition that chiefly affects women. Lysine encourages bone cells to build new bone. Always check with your doc before starting to take lysine supplements because too much is associated with increased risk for developing gallstones. It may also interfere with certain medications.

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