The Health Benefits of Lysine

May help with cold sores, stress relief, and bone health

Lysine capsules, tablets, beans, eggs, and nuts

Verywell / Anastasia Tretiak

Lysine is an essential amino acid. Reported lysine benefits include improved blood sugar control, management of anxiety and stress, collagen formation, and wound healing. Your body cannot make lysine, so you must get it from food or supplements.

There are two chemical versions of lysine: L-lysine and D-lysine. L-lysine is the bioactive form found in foods and supplements that your body uses, and it's our focus here.

In addition to potential lysine benefits and uses, read on to learn about lysine supplement doses, side effects, food sources, and more.

Supplement Facts

●     Active Ingredients: Lysine

●     Alternate Names: L-lysine, L-lysine hydrochloride

●     Legal Status: Legal, over the counter (OTC)

●     Suggested Dose: Dosage varies, but is generally considered safe at 6 grams (g) or less per day

●     Safety Considerations: Upset stomach, diarrhea, nausea, kidney failure, impaired calcium absorption

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent disease.

Lysine Benefits

Because lysine is an amino acid, your body uses it to make proteins and repair muscles.

Lysine supplements may provide benefits for the following:

The research on many of these benefits is limited. Talk with a healthcare provider before starting lysine supplements to ensure they are safe for you.

Cold Sores

Cold sores are an unpleasant side effect of HSV 1.

A 2017 review found that oral lysine supplementation of 3 grams (g) per day or more improved the experiences of some people with cold sores. However, the review stated that more research is needed to determine whether lysine is an effective treatment for this condition.

An earlier review conducted in 2015 also did not find enough evidence to back up claims that lysine can provide cold sore relief.

Stress and Anxiety

Studies have looked at whether lysine can help manage anxiety and stress. Research is limited, and it should be noted that many of the studies are small and don't include many participants.

A randomized, double-blind study found that cortisol (a hormone that's increased during stress), was lowered in people who consumed lysine-fortified foods for three months. The study also found that these foods reduced anxiety measures in males.

Schizophrenia

Lysine may also be used as a complementary treatment for schizophrenia, according to limited research.

A small pilot study reported that people taking 6 g of lysine daily for four weeks had improved symptoms, including reduced psychosis severity. However, the researchers reported that possible placebo effects could have impacted the self-reported findings.

A randomized, controlled trial looked at the use of 6 g of L-lysine with risperidone (a drug used to treat mental conditions), in people with schizophrenia over eight weeks. The study showed that schizophrenia symptoms decreased more for people who took L-lysine. However, the safety and efficacy of higher doses and longer-term use of L-lysine are still uncertain.

Blood Sugar Control

Lysine supplements may be useful for lowering blood sugar.

A very small study found that high doses of lysine (11 g) taken with glucose resulted in small decreases in blood sugar. Researchers think that lysine supplementation may either help with insulin secretion or help remove glucose from the blood on its own.

However, more research is needed. Follow your healthcare provider's guidance for blood sugar control.

Osteoporosis

Lysine supplements may help the body absorb calcium, which can be beneficial for osteoporosis (a disease that causes weak, brittle bones).

However, many studies have been done in vitro (in a lab or test tube) or on animals. This means that it's difficult to definitively conclude the effect of lysine on treating osteoporosis in humans.

An older review on two small human trials concluded that lysine supplementation helped people absorb more calcium, a mineral vital to bone health. However, no recent trials examine lysine's effects in humans with osteoporosis.

One study on rats concluded that dietary lysine increased the amount of calcium absorbed by the body. The study also reported that lysine supplementation prevented the rats from experiencing loss of bone matter, as seen in osteoporosis. It's important to note that this study was conducted in rats and did not involve human participants. We cannot say that these effects will even happen in humans.

More high-quality studies using lysine need to be done with humans before further conclusions are made. If you have osteoporosis, follow your doctor's prescribed treatment plan. Consult your healthcare provider before taking any supplements.

Side Effects

While lysine supplements are generally considered safe for most people, side effects are possible.

Common Side Effects

Common side effects of lysine supplements include:

Typically, these gastrointestinal side effects don't last for long and can be treated at home. They usually only occur with larger doses of lysine.

However, if you experience long-term side effects from taking oral lysine, visit your healthcare provider.

Severe Side Effects

Severe side effects are rare but possible, like kidney failure.

Kidney failure has been reported from taking too much lysine. One case report on a 44-year-old woman found that high doses of lysine caused Fanconi Syndrome, a severe disorder involving the kidneys. Her symptoms eventually led to kidney failure.

As this case report was done on just one person, the evidence of kidney failure associated with taking lysine is limited. Additional research available on this topic has mostly been performed on animal models.

Eggs, nuts, and beans
Verywell / Anastasia Tretiak

Who Shouldn't Take Lysine Supplements

Certain people should avoid taking lysine supplements, including:

  • People who are pregnant or breastfeeding: There is not enough evidence to know if lysine is safe for these populations.
  • People who take calcium supplements: Lysine may increase the amount of calcium your body absorbs, which could potentially lead to hypercalcemia.
  • Anyone with lysinuric protein intolerance: This is a rare condition in which the body cannot properly digest lysine and other amino acids.

It's important to talk to your healthcare provider first before starting any new supplements.

Interactions

Possible food, drug, or supplement interactions with lysine include:

  • Arginine (another amino acid): Taking a large dose of arginine with lysine may cause lower levels of lysine absorption. This is because some receptors in your body prefer arginine over lysine.
  • Calcium: Lysine has been found to increase the amount of calcium absorbed in the digestive tract.
  • It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included.

    Lysine Dosage

    There is no standard recommended dose for lysine supplements. Fortunately, most people can get enough lysine through their diet.

    Various studies on lysine for cold sores have used a wide range of doses from 300 milligrams per day to 3 grams per day. Other studies performed on lysine supplements have used even higher amounts.

    Because there is no standardized dose for lysine, it's best to talk with your healthcare provider before starting lysine supplements. They may be able to determine the best dosage for you and answer any lingering questions.

    What Happens If You Take Too Much Lysine?

    Lysine is considered to be a safe, non-toxic supplement to take.

    There is no upper limit, or maximum dose because the side effects of taking larger amounts are not severe. Some researchers suggest taking no more than 6 grams of lysine per day.

    Experiencing any common side effects after taking oral lysine may indicate that you've taken too much. Follow your healthcare provider's advice on how much lysine you should take.

    Sources of Lysine

    Lysine is an amino acid found in various protein foods, so most people can get all the lysine they need through their diet.

    Since lysine is so widely available in food, taking a food-first approach to getting enough of it is recommended. Lysine supplements would only be required if recommended by a healthcare professional due to an underlying health issue.

    Some people, like those who follow a vegan diet, may have difficulty getting enough lysine.

    Food

    The best sources of lysine come from animal foods, but it can also be found in some plant-based proteins.

    The best way to ensure you're getting enough lysine in your diet is to eat a variety of protein foods, including both animal and plant sources. The recommended daily intake for lysine is 35 milligrams per kilogram (kg) of body weight.

    Non-vegan food sources of lysine include:

    • Meat
    • Chicken
    • Dairy products
    • Eggs
    • Fish

    Vegan food sources of lysine include:

    Lysine Supplements

    Lysine supplements are available in various forms, including:

    • Capsules
    • Chewable
    • Powders

    The right form of supplement for you will depend on personal preferences.

    Many lysine supplements are also vegan or gluten-free. The label should tell you whether the supplement is either vegan or gluten-free. The label should also list the supplement form.

    Topical lysine (cream) is also available, but only in combination form. This means that lysine creams will include other ingredients, like other various vitamins, minerals, or nutrients.

    What to Look For

    Check the supplement facts label before buying any dietary or herbal supplements. The label provides important information about the number of active ingredients per serving. It should also include information about other ingredients in the supplement.

    Look for a product that has been quality tested by an independent organization. Supplements that have been quality tested will include the logo of the testing agency on the label. Examples of quality testing agencies include:

    • US Pharmacopeia (USP)
    • National Science Foundation (NSF)
    • ConsumerLab.com

    How to Store Lysine

    Lysine supplements should be stored in a cool, dry place that does not receive direct sunlight. Be sure to avoid storing your supplements in an area that could become overly hot or cold.

    Do not store In the bathroom.

    Discard lysine supplements after one year or as indicated on the packaging.

    Similar Supplements

    Other supplements that have been studied for the same uses as lysine include:

    Summary

    Lysine is an essential amino acid that can be found in high-protein foods like meat, nuts, beans, and eggs. It is also available as an oral supplement for those who need it. However, taking a food-first approach to getting enough of it is usually recommended.

    Some research suggests that lysine may be helpful for treating certain conditions, like cold sores and anxiety. More research is needed to determine the full extent of lysine's safety and efficacy when used for these conditions. Before taking lysine, talk to your healthcare provider about dosage and how to best use the supplement.

    Frequently Asked Questions

    • Is lysine safe to take when pregnant?

      Lysine may be safe to take while pregnant, but researchers and healthcare professionals do not know for sure. For this reason, it would be best to avoid taking lysine supplements during pregnancy and while breastfeeding.

      People who are pregnant or breastfeeding should be able to get enough lysine from a healthy diet.

    • Can your body make lysine?

      Lysine is an essential amino acid and cannot be made by the body. Because of this, you must get all the lysine you need through food and supplements.

      There are nine essential amino acids: lysine, leucine, isoleucine, histidine, methionine, threonine, phenylalanine, tryptophan, and valine.

    • What does lysine do for you body?

      Besides potentially treating health conditions like cold sores, high blood sugar, and osteoporosis, lysine has other roles in the body.

      Your body uses lysine to make carnitine, which is needed to make energy. Lysine also helps your body make enough collagen, an important protein found in your skin.

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    By Brittany Lubeck, RD
    Brittany Lubeck, RD, is a nutrition writer and registered dietitian with a master's degree in clinical nutrition. 

    Originally written by
    Cathy Wong
    Cathy Wong

    Cathy Wong is a nutritionist and wellness expert. Her work is regularly featured in media such as First For Women, Woman's World, and Natural Health.

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