This Amino Acid May Help Support Mood, Sleep, and Cognitive Health—What To Know

Tryptophan is an essential amino acid—meaning it must be obtained from diet—that is found in many proteins. Tryptophan is necessary to help build many peptides and proteins in the body, supporting many biological functions.

Tryptophan may help produce several important compounds, including serotonin and melatonin. For this reason, tryptophan may improve health conditions such as mood disorders, sleep, and age-related cognitive decline.

Researchers have studied the use of tryptophan for treating mood disorders, such as anxiety and depression, as well as other neurological conditions. The research results so far have been conflicting on whether tryptophan can help these disorders.

Once in the body, tryptophan is converted to a product called 5-hydroxytryptophan (5-HTP) in the stomach. 5-HTP is then converted to serotonin. Serotonin is a hormone that can affect your mood, sleep, and stress. Serotonin can then be converted into melatonin, the hormone that helps with sleep.

Anxiety and Depression

Tryptophan helps produce serotonin in the body. Several bodily processes involve serotonin, including blood clotting, sleep, appetite, and memory. It is most commonly known as the hormone that helps control your mood and makes you “feel happy.” In theory, increasing your tryptophan levels will help increase your serotonin levels, improving your mood.

Data on tryptophan’s role in mood disorders like anxiety and depression are conflicting. Some studies have found that consuming a high-tryptophan diet may lead to a more positive mood. This data typically occurs in studies involving people without preexisting conditions. People with a history of severe mood disorders did not see as much benefit.

More studies are needed to understand whether tryptophan supplementation would be useful in treating mood disorders such as anxiety and depression.

Sleep Disorders

Have you ever felt especially sleepy after eating turkey on Thanksgiving? This may be due to the tryptophan found in the turkey. Clinical studies have found that tryptophan, through diet or supplementation, may help improve sleep quality.

In the body, tryptophan received from your diet is converted to melatonin. Melatonin is the hormone responsible for the sleep-wake cycle. Melatonin is released in response to darkness, helping you fall asleep. Serotonin is also relevant to the sleep-wake cycle, helping to regulate brain activity during the various cycles.

Researchers have found that tryptophan doses of 1 gram or higher may help improve sleep quality by helping you stay asleep longer. More research is needed to understand how tryptophan may help with other components of sleep and the full extent of the amino acid’s impact on sleep.

Age-Related Cognitive Decline

Due to its role in increasing serotonin production, tryptophan may also help prevent age-related cognitive decline. One study found that typical signs of cognitive decline in the brain were delayed in rats receiving a high tryptophan diet. Human research is still needed to understand how the supplement affects the brain.

Autism Spectrum Disorder

Research has shown that children with autism spectrum disorder (ASD) may have low levels of tryptophan in the body. Low levels of tryptophan may affect the production of other important compounds, such as serotonin and melatonin, and worsen autism symptoms.

One small study examined the relationship between tryptophan levels and symptoms in children with ASD. They compared the amount of tryptophan in the bodies of children who received B vitamins and magnesium supplements to children who did not. Children receiving the B vitamins and magnesium supplements had more stable levels of tryptophan and did not lose as much of the amino acid through the urine.

It is unclear what role tryptophan levels play in autism symptoms or how beneficial B vitamins and magnesium are in the regulation of tryptophan. More research is needed to truly understand the role tryptophan may play in treating or maintaining ASD.

Tryptophan may be helpful in the following conditions:

Athletic performance: Small studies have found that tryptophan may improve your power output and lower your feelings of exhaustion during exercise.
Cardiovascular disease: Research has found that high tryptophan levels are associated with a lower risk of cardiovascular (heart and blood vessel) disease.
Gastrointestinal disease: People with gastrointestinal conditions, such as inflammatory bowel disease (IBD) or Crohn’s disease, have lower levels of tryptophan.
Migraines: Low levels of serotonin are common in people with migraines. Researchers have found that tryptophan supplementation may help lower the chances of developing a migraine.

More research on the benefits of tryptophan is needed for each of these conditions.

A typical diet in the United States provides about 0.5-2 grams of tryptophan a day. Sources of tryptophan include:

Poultry products, such as turkey, chicken, and eggs
Red meats, such as beef, lamb, and pork
Seafood
Dairy, such as cheddar cheese and milk
Nuts and seeds
Legumes
Whole grains

Tryptophan supplements are available in powder or tablet form. It can be found by itself or as a combination product with other amino acids or compounds.

Dosage

Tryptophan can be taken in doses of 200 milligrams to 6 grams daily for up to six weeks. In studies for mood disorders, tryptophan doses typically range from 0.14-3 grams daily, not including tryptophan from the diet. If you are looking to take tryptophan to treat mood disorder symptoms, talk to your healthcare provider first about safety and dosage.

Doses of up to 5 grams of tryptophan daily for 21 days have been reported as safe for healthy adults. Experts recommend an upper level of safe intake (USLI) of 4.5 grams daily for tryptophan in adults without health conditions.

Tryptophan supplements may affect fetal breathing. Taking tryptophan supplements outside of typical dietary forms (foods) is not recommended in people who are pregnant or breastfeeding.

Potential Drug Interactions

Common drugs that may interact with tryptophan supplementation include:

Central nervous system (CNS) depressants: Taking tryptophan with any CNS depressant may cause dangerous levels of drowsiness, tiredness, or issues with breathing. CNS depressants include benzodiazepines, muscle relaxers, and certain sleep medicines.
Serotonergic drugs: Tryptophan may increase your levels of serotonin and the risk of serotonergic side effects, especially if taken with other drugs that have serotonergic properties, such as certain medications used to treat anxiety and depression. High levels of serotonin can lead to a condition called serotonin syndrome. Common symptoms include heart problems, seizures, vomiting, and confusion.

What To Look For

The United States Food and Drug Administration (FDA) does not regulate supplements like tryptophan. When shopping for tryptophan products, look for supplements tested by independent third-party organizations to ensure the accuracy and purity of the ingredients in the product. Popular organizations that offer quality testing include United States Pharmacopeia (USP), NSF International, and ConsumerLab.com. You can look for their labels on the product packaging.

Tryptophan is not always listed as an ingredient in dietary supplements. Instead, It may be reported as “niacin,” a vitamin that tryptophan helps create. One milligram of niacin (also called the niacin equivalent) equals 60 milligrams of tryptophan.

Can You Take Too Much?

Taking high doses of tryptophan is unlikely to cause adverse health effects. However, experts generally recommend not taking more than 4.5 grams per day.

Tryptophan is generally well tolerated. Side effects of tryptophan include:

Belching
Blurred vision
Diarrhea
Drowsiness
Dry mouth
Flatulence (gas)
Headache or lightheadedness
Heartburn
Nausea and vomiting
Stomach pain

In 1989, tryptophan was linked to reports of a severe syndrome called eosinophilia-myalgia syndrome (EMS) and deaths. EMS is a neurological disorder that can cause inflammation around the heart, abnormal heart rhythms, skin rash, joint pain, and increased white blood cells. These reports led the FDA to remove tryptophan from the market in 1990.

However, EMS likely occurred due to contamination of tryptophan products created by one specific drug manufacturer in Japan. Since 1994, the FDA has considered tryptophan a safe and marketable supplement.

Tryptophan is an essential amino acid that you must obtain through your diet. It is necessary to help carry out several bodily functions and produce other compounds like serotonin and melatonin. Research suggests tryptophan may help with health conditions such as mood disorders, sleep, and age-related cognitive decline.

You can get tryptophan through foods like poultry, dairy, and whole grains, as well as through supplements. If you have questions about tryptophan supplementation, talk with your healthcare provider.