Some evidence suggests that L-tryptophan supplements may help to treat conditions such as anxiety and sleep disorders. However, more research into the safety and efficacy of L-tryptophan supplements is necessary.

L-tryptophan is an essential amino acid that performs many functions in the body, including the production of serotonin. Serotonin is a chemical in the brain that affects mood.

Although some evidence suggests that L-tryptophan may help with certain conditions, such as anxiety or sleep disorders, additional research is necessary to prove whether or not taking L-tryptophan supplements is effective.

This article examines the safety and efficacy of L-tryptophan supplements.

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L-tryptophan, or tryptophan, is an essential amino acid that plays a part in creating serotonin. Serotonin is a hormone present in various parts of the body, including the brain. The serotonin in the brain helps regulate a person’s mood, anxiety, and levels of happiness.

L-tryptophan is also available as a supplement.

Because L-tryptophan plays a role in the production of serotonin in the brain, some experts suspect that it may help with conditions such as anxiety and sleep disorders. There is some evidence to support its use for these purposes.


In one small study of 25 young adults, the researchers found that changing the diets of the participants to include more L-tryptophan created positive changes in their mood. It also reduced symptoms of anxiety and depression.

In a 2016 review, the researchers found that there may be a connection between low levels of L-tryptophan and depression and anxiety symptoms in rodents.

In humans, the authors noted that those most likely affected are people with risk factors for developing depression. It is possible that at risk populations may benefit from increased tryptophan levels.


In a 2016 study of young people undergoing drug detox, the researchers found that the participants saw minimal or no improvements in mental symptoms associated with their detox process.

However, they did note that L-tryptophan was effective in helping the participants sleep during the detox process. The researchers also noted that additional studies are necessary to prove how effective it may actually be.

Premenstrual dysphoric disorder

According to an older study, L-tryptophan may help alleviate pain associated with premenstrual dysphoric disorder. The study also found that people who had limited amounts or none of the amino acid in their diets had worse symptoms of premenstrual syndrome (PMS).

Pain tolerance

In a 2017 study, the researchers examined how L-tryptophan levels affect a person’s tolerance for pain. The study found that higher levels of this amino acid made pain more manageable.

L-tryptophan is safe when a person consumes it as part of their regular diet. When consuming it in supplement form, a person may experience minor side effects.

According to one study, some common but mild side effects include:

  • nausea
  • tremor
  • sleepiness (in those not taking it for sleep disorders)
  • dizziness

Although this is not common, a person may experience serotonin syndrome if they take multiple medications for depression or anxiety at the same time.

Though rare, serotonin syndrome is most likely to occur when a person takes an L-tryptophan supplement with medications that alter serotonin levels, such as antidepressants.

Symptoms of serotonin syndrome may include:

  • coma
  • involuntary twitching or jerking
  • delirium
  • hyperthermia

In 1989, researchers temporarily linked tryptophan supplements to eosinophilia myalgia syndrome (EMS). EMS causes symptoms such as debilitating muscle pain and a high peripheral eosinophil count. The cause of EMS turned out to be a bad batch and not the result of the supplement itself.

It is also important to note that the Food and Drug Administration (FDA) do not currently regulate supplements.

However, there are several different independent testing agencies that do look at supplements for purity and potency. People should look for supplements that have certification from third party evaluators to help minimize their risk of exposure to bad products or ineffectiveness.

L-tryptophan is naturally present in many foods. Some food sources include:

  • turkey
  • tuna
  • nuts
  • seeds
  • bananas
  • dairy products
  • red meat
  • shellfish
  • soy products

It is not likely that the amount of the nutrient present in food will have any positive or negative effects on a person’s sleep or mood.

Melatonin is another supplement that people may use to help ease insomnia or sleep disorders. Melatonin is a hormone that the body releases to stimulate sleep in the evening and waking in the morning.

A person can also try non-supplement-related sleep aids. Some steps that may help facilitate a better night of sleep include:

  • drinking warm milk
  • ensuring that the bedroom is cool and dark
  • exercising during the day

People should talk to their doctor if they have other conditions that they were considering using L-tryptophan for to get advice on possible treatments.

People should talk to their doctor before starting any supplement. In particular, people who take antidepressants should talk to their doctor before taking L-tryptophan supplements.

People should stop taking the supplement and talk to their doctor if they notice any unusual symptoms after taking it.

L-tryptophan may be an effective sleep aid and may also help with other conditions, such as chronic pain, anxiety, depression, or PMS.

However, the supplement may not be for everyone, and it may not be helpful for all conditions. People should talk to their doctor before starting a new supplement, and they should stop using it if they experience any side effects.

More research is necessary to determine whether or not L-tryptophan is safe and effective in easing any of these conditions.