L-Lysine is an essential amino acid. Here's why it matters.
While research shows that the global dietary supplements' market was already exploding back in 2021 when it was valued at more than $152 billion, the industry is showing no signs of slowing down. In fact, one report shows that the global market will reach a staggering $300 billion by 2028.
Though dietary supplements aren't regulated in the United States by the Food and Drug Administration the same way foods and drugs are - and many popular supplements have been shown to be ineffective or even dangerous in high amounts - most of the supplements sold in the industry are considered to be generally safe when taken as directed.
Among the most commonly taken supplements is L-Lysine, though registered dietitians don't usually stress a need to take it unless you have a medical condition or dietary restriction that prevents you from getting enough of it naturally in your diet.
What is L-Lysine?
L-Lysine, or lysine, is an amino acid - which are organic compounds that link together to form proteins. Lysine is considered an essential amino acid because the body needs it but can't produce it. "Lysine is a necessary building block for the proteins in every cell of our body," says Dr. Walter Willett, a physician and professor of epidemiology and nutrition at Harvard T. H. Chan School of Public Health.
Because the body doesn't make lysine, we need to get it from dietary sources. Fortunately, "very few generally healthy Americans are protein deficient," says Willett. This is because the amino acids (including lysine) that form protein are abundant in most protein-rich food sources such as eggs, meat like pork, beef, chicken and fish, and dairy such as milk, yogurt and cheese. Willett says lysine is also in all whole plant foods such as wheat and beans.
In other words, if you're eating a well-balanced diet, you're already getting plenty of the lysine and other amino acids your body needs.
At the same time, people with certain medical conditions or people with dietary restrictions that cause them to be deficient in protein are sometimes encouraged to take L-Lysine as a dietary supplement.
As a supplement, L-Lysine is available in pill, powder, liquid, and cream form.
What is L-Lysine good for?
Lysine has many important functions and health benefits. It helps the body absorb calcium - which is important for bone health; it supports a healthy immune system by helping with the production of antibodies; research shows it may reduce feelings of stress and anxiety by lowering cortisol levels; and it plays important roles in protein synthesis such as helping with the production of enzymes and hormones and by aiding in tissue growth and repair. Lysine can also help with the formation of collagen production, making it important for skin health.
But again, the vast majority of people receive all associated benefits simply by eating a wide variety of healthy foods.
As a supplement, lysine is most commonly recommended to prevent herpes outbreaks and especially cold sores, says Dr. Denise Millstine, a women's health specialist and director of the Mayo Clinic integrative medicine clinic in Arizona. But in research, she says, lysine's strength is in preventing outbreaks, "and very little data supporting using it as a treatment for an active cold sore." It's helpful in this way because lysine has antiviral effects that block the activity of arginine, which promotes replication of the herpes virus, per the Mount Sinai Hospital in New York.
The role lysine has in improving muscle and bone structure, "is one reason lysine supplements are often also promoted to help with bodybuilding," says Willett, though no studies support taking it as a supplement for that purpose.
Lysine supplements are also often touted for boosting a healthy immune system, "and some animal studies have offered a potential mechanism for this effect," explains Millstine, "but that has not been demonstrated so far in human studies."
Is L-Lysine OK to take as a supplement?
Despite there being very little scientific evidence that supports taking lysine as a supplement to enhance athletic performance, improve skin quality, prevent one from getting sick, and many other purported benefits, taking up to 3,000 milligrams (3 grams) of it as a supplement daily is generally considered to be safe for most people.
If taken in excess, Millstine says lysine supplements can cause adverse digestive issues such as an upset stomach and diarrhea - and Willett says there may be more serious risks associated with taking it over extended periods of time, though he says long-term adverse effects "are not well studied."
"Outside of using it for the prevention of a herpes outbreak," Millstine adds, "it is likely sufficient to get L-Lysine from protein food sources."
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This article originally appeared on USA TODAY: What is L-Lysine?
