The amino acid tryptophan has many health benefits, but its effects on brain health are worth noting. It affects your mood, cognition and behavior, as well as your sleep cycles.
It is needed by the body to make proteins and other important molecules, including those critical for optimal sleep and mood.
In particular, tryptophan can be converted into a molecule called 5-HTP (5-hydroxytryptophan), which is used to make serotonin and melatonin (2, 3).
Serotonin affects several organs, including the brain and intestines. Specifically in the brain, it affects sleep, cognition, and mood (4, 5).
Taken together, tryptophan and the molecules it produces are essential for the body to function optimally.
Summary Tryptophan is an amino acid that can be converted into several important molecules, including serotonin and melatonin. Tryptophan and the molecules it produces affect many bodily functions, including sleep, mood, and behavior.
Several studies have shown that people with depression may have lower than normal levels of tryptophan (7, 8).
By lowering tryptophan levels, researchers can learn about its function. To do this, study participants consumed large amounts of amino acids with or without tryptophan (9).
In one study, 15 healthy adults were exposed to a stressful environment twice: once when they had normal blood tryptophan levels and once when they had low blood tryptophan levels (10).
The researchers found that when participants had lower levels of tryptophan, anxiety, nervousness, and nervousness were higher.
Summary: Research shows that low tryptophan levels may contribute to mood disorders, including depression and anxiety.
One study found that when tryptophan levels were lowered, long-term memory performance was worse than at normal levels (14).
In addition, a large review found that lower levels of tryptophan negatively impact cognition and memory (15).
These effects may be related to reduced tryptophan levels and decreased serotonin production (15).
Summary: Tryptophan is important for cognitive processes due to its role in serotonin production. Low levels of this amino acid can impair your cognitive abilities, including memory of events or experiences.
In vivo, tryptophan can be converted to 5-HTP molecules, which then form serotonin (14, 16).
Based on numerous experiments, researchers agree that many of the effects of high or low tryptophan levels are due to its effect on serotonin or 5-HTP (15).
Serotonin and 5-HTP interfere with many processes in the brain, and interfering with their normal activities can cause depression and anxiety (5).
In fact, many medications used to treat depression alter how serotonin works in the brain, increasing its activity (19).
5-HTP treatment can also help increase serotonin levels and improve mood, as well as reduce panic attacks and insomnia (5, 21).
Overall, the conversion of tryptophan to serotonin is responsible for many of the observed effects on mood and cognition (15).
Summary: The importance of tryptophan may be due to its role in the production of serotonin. Serotonin is essential for the proper functioning of the brain, and low levels of tryptophan can reduce the amount of serotonin in the body.
When serotonin is produced in the body from tryptophan, it can be converted into another important molecule, melatonin.
In fact, research shows that increasing blood levels of tryptophan directly increases serotonin and melatonin levels (17).
In addition to melatonin, which is naturally present in the body, melatonin is also a popular supplement found in a variety of foods, including tomatoes, strawberries, and grapes ( 22Trusted Source ).
Melatonin affects the body’s sleep-wake cycle. This cycle affects many other functions, including nutrient metabolism and the immune system (23).
Several studies have shown that increasing dietary tryptophan improves sleep by increasing melatonin (24, 25).
One study found that eating tryptophan-rich cereal for breakfast and dinner helped adults fall asleep faster and sleep longer compared to eating standard cereal (25).
Symptoms of anxiety and depression have also been reduced, and tryptophan is likely to increase serotonin and melatonin levels.
Other studies have also shown that taking melatonin as a supplement improves the amount and quality of sleep (26, 27).
Summary: Melatonin is important for the body’s sleep-wake cycle. Increasing tryptophan intake can increase melatonin levels and improve the quantity and quality of sleep.
Some foods are especially high in tryptophan, including poultry, shrimp, eggs, moose and crabs (28).
You can also add tryptophan or one of the molecules it makes, like 5-HTP and melatonin.
Summary: Tryptophan is found in foods containing protein or supplements. The exact amount of protein in your diet will vary depending on the amount and type of protein you eat, but it is estimated that a typical diet provides about 1 gram of protein per day.
If you’re looking to improve your sleep quality and health, tryptophan supplements are worth considering. However, you have other options.
You may decide to add molecules derived from tryptophan. These include 5-HTP and melatonin.
If you take tryptophan itself, it can be used for other body processes besides serotonin and melatonin production, such as protein or niacin production. This is why supplementing with 5-HTP or melatonin may be a better option for some people (5).
Those looking to improve mood or cognitive performance can take tryptophan or 5-HTP supplements.
In addition, 5-HTP has other effects, such as reduced food intake and body weight (30, 31).
For those most interested in improving sleep, a melatonin supplement may be the best option (27).
Summary: Tryptophan or its products (5-HTP and melatonin) can be taken alone as a dietary supplement. If you choose to take one of these supplements, the best choice depends on the symptoms you are targeting.
Because tryptophan is an amino acid found in many foods, it is considered safe in normal amounts.
The typical diet is estimated to contain 1 gram per day, but some people choose to take supplements of up to 5 grams per day ( 29Trusted Source ).
Its possible side effects have been studied for over 50 years, but there are few reports of it.
However, side effects such as nausea and dizziness have occasionally been reported at doses greater than 50 mg/kg body weight or 3.4 g in adults weighing 150 pounds (68 kg) (29).
Side effects may be more pronounced when taking tryptophan or 5-HTP with drugs that affect serotonin levels, such as antidepressants.
When serotonin activity increases excessively, a condition known as serotonin syndrome can occur (33).
If you are taking any medications that affect serotonin levels, check with your doctor before taking tryptophan or 5-HTP supplements.
Summary: Studies of tryptophan supplementation have shown little effect. However, nausea and dizziness have occasionally been observed at higher doses. Side effects may become more severe with medications that affect serotonin levels.
Serotonin affects your mood, cognition, and behavior, while melatonin affects your sleep-wake cycle.