What is 5-HTP?
5-HTP is an amino acid and a precursor to the neurotransmitter serotonin. It is produced in the body from the essential amino acid tryptophan, and it can be supplemented directly. Plants are a rich source of 5-HTP, and Griffonia simplicifolia seeds are often used for the extraction and the commercial production of 5-HTP.[4]
What are 5-HTP’s main benefits?
5-HTP is very reliable for increasing serotonin levels in presynaptic neurons in the brain and is actually used as a test drug to help determine the potency of other serotonin-increasing substances.[5]
Most of the research has looked at 5-HTP for its potential role in treating depression. This is based on the serotonin theory of depression — the debatable theory that depression is the result of low serotonin in the brain.[6] While some research has been promising, the body of evidence is weak overall. Most of this research was conducted in the 1970s and 1980s with poor methodological quality.[1][7]
5-HTP may reduce symptoms of depression compared to a placebo when taken alone or in addition to standard treatment.[1] Also, two short-term studies (6 to 8 weeks) reported that 5-HTP reduced symptoms of depression to a similar degree as the SSRI antidepressant medications fluoxetine and fluvoxamine.[8][9] While this is promising, higher quality research is needed to confirm these effects.
5-HTP may also play a role in appetite regulation. In people with overweight or obesity, researchers have observed weight loss due to reduced calorie intake and increased satiety, or the feeling of fullness, during supplementation with 5-HTP.[2][3][10]
5-HTP has also been studied for its effects on migraine or tension headache prevention,[11][12][13] fibromyalgia,[14][15] and Parkinson’s disease.[16][17] Currently, research is mixed and largely inconclusive.
What are 5-HTP’s main drawbacks?
5-HTP can cause mild side effects which may improve over time. These include nausea, abdominal pain, and diarrhea, and less commonly fatigue, insomnia, and headaches. Intravenous administration of 5-HTP has been reported to cause confusion, anxiety, and memory impairment.[18][1]
At high doses (100–200 mg per kg of body weight), 5-HTP has been associated with serotonin syndrome in lab animals, a severe condition caused by high levels of serotonin in the body.[1] In rodents, the risk of serotonin syndrome was increased when 5-HTP was combined with SSRIs (commonly used antidepressant medications). There are no reports of toxicity at normal doses, and it should be noted that serotonin syndrome from 5-HTP supplementation has not been observed in humans.[1]
In 1989 and 1990, there were over 1,500 cases of eosinophilia myalgia syndrome (EMS) (a rare syndrome with symptoms of severe muscle pain and fatigue) leading to over 30 reported deaths in people taking tryptophan supplements, a direct precursor to 5-HTP. Additionally, there were a few cases of EMS reported with 5-HTP supplementation. It was determined that EMS likely occurred due to a toxic contaminant in the supplements, and there have been no confirmed cases in recent years. Regardless, this led to a stark decline in the use of and research on tryptophan and 5-HTP supplements. To avoid the risk of EMS, it is important that 5-HTP supplements are purified and tested for contaminants.[1][19]
How does 5-HTP work?
5-HTP acts as a direct precursor for the neurotransmitter serotonin. 5-HTP readily crosses the blood-brain barrier, which can lead to increased serotonin levels in presynaptic neurons in the brain. This may play a role in regulating mood, sleep, appetite, memory, and various other processes.[4]
However, it’s also important to note that the relationship between serotonin levels and depression is not as clear as many people think. The current body of evidence does not consistently show that lower levels of serotonin are associated with or cause depression.[6]
What are other names for 5-HTP
- 5-hydroxytryptophan
- L-5-Hydroxytryptophan
- L-5HTP
- Oxitriptan
- 5-Hydroxytryptamine (Serotonin or 5-HT)
- Tryptophan
Dosage information
5-HTP is usually taken orally in capsule form. It can be taken once daily or in divided doses (i.e., the total daily dose is split into two or three doses).
For depression, most studies have used dosages in the range of 200 mg to 300 mg daily for up to 1 year.[1]
For weight loss or appetite regulation, 5-HTP has been used in the range of 750 mg to 900 mg daily for up to 6 weeks.[2][3]
Frequently asked questions
5-HTP is an amino acid and a precursor to the neurotransmitter serotonin. It is produced in the body from the essential amino acid tryptophan, and it can be supplemented directly. Plants are a rich source of 5-HTP, and Griffonia simplicifolia seeds are often used for the extraction and the commercial production of 5-HTP.[4]
5-HTP is very reliable for increasing serotonin levels in presynaptic neurons in the brain and is actually used as a test drug to help determine the potency of other serotonin-increasing substances.[5]
Most of the research has looked at 5-HTP for its potential role in treating depression. This is based on the serotonin theory of depression — the debatable theory that depression is the result of low serotonin in the brain.[6] While some research has been promising, the body of evidence is weak overall. Most of this research was conducted in the 1970s and 1980s with poor methodological quality.[1][7]
5-HTP may reduce symptoms of depression compared to a placebo when taken alone or in addition to standard treatment.[1] Also, two short-term studies (6 to 8 weeks) reported that 5-HTP reduced symptoms of depression to a similar degree as the SSRI antidepressant medications fluoxetine and fluvoxamine.[8][9] While this is promising, higher quality research is needed to confirm these effects.
5-HTP may also play a role in appetite regulation. In people with overweight or obesity, researchers have observed weight loss due to reduced calorie intake and increased satiety, or the feeling of fullness, during supplementation with 5-HTP.[2][3][10]
5-HTP has also been studied for its effects on migraine or tension headache prevention,[11][12][13] fibromyalgia,[14][15] and Parkinson’s disease.[16][17] Currently, research is mixed and largely inconclusive.
5-HTP is a precursor for serotonin which can be further processed into melatonin. Despite this theoretical mechanism for promoting sleep, current research is limited and not particularly promising.
Some early research in the 1970s suggested that 5-HTP might increase REM sleep without affecting total sleep duration, but several participants reported experiencing nightmares.[20][21] Furthermore, a 2022 randomized controlled trial in people with Parkinson’s disease found no effect on REM sleep.[22]
In children with sleep terrors, 5-HTP was reported to significantly reduce night terror episodes, but the study was not placebo-controlled.[23]
In a 2024 study (summarized here), 5-HTP taken before bed for 12 weeks did not improve sleep but rather was reported to slightly decrease sleep duration in older adults.[24]
Tryptophan is an essential amino acid found in some foods and dietary supplements. Tryptophan can be converted into 5-HTP in the body; however, supplementing with 5-HTP directly is more reliable for increasing serotonin levels.
The conversion of tryptophan to 5-HTP is the rate-limiting step for the synthesis of both serotonin and melatonin. This means that the speed with which the body can produce serotonin or melatonin relies on how quickly tryptophan can be converted to 5-HTP. When supplementing with 5-HTP, this rate-limiting step is bypassed.[4]
Several factors can limit the conversion of tryptophan to 5-HTP. For one, tryptophan has many different fates within the body (such as protein synthesis), meaning only a small fraction is converted to 5-HTP and subsequently serotonin. However, 5-HTP has the sole purpose of serotonin synthesis. Furthermore, tryptophan has to compete with other amino acids for entry into the brain, while 5-HTP can passively enter the brain without challenge.[18][25][26]
5-HTP can cause mild side effects which may improve over time. These include nausea, abdominal pain, and diarrhea, and less commonly fatigue, insomnia, and headaches. Intravenous administration of 5-HTP has been reported to cause confusion, anxiety, and memory impairment.[18][1]
At high doses (100–200 mg per kg of body weight), 5-HTP has been associated with serotonin syndrome in lab animals, a severe condition caused by high levels of serotonin in the body.[1] In rodents, the risk of serotonin syndrome was increased when 5-HTP was combined with SSRIs (commonly used antidepressant medications). There are no reports of toxicity at normal doses, and it should be noted that serotonin syndrome from 5-HTP supplementation has not been observed in humans.[1]
In 1989 and 1990, there were over 1,500 cases of eosinophilia myalgia syndrome (EMS) (a rare syndrome with symptoms of severe muscle pain and fatigue) leading to over 30 reported deaths in people taking tryptophan supplements, a direct precursor to 5-HTP. Additionally, there were a few cases of EMS reported with 5-HTP supplementation. It was determined that EMS likely occurred due to a toxic contaminant in the supplements, and there have been no confirmed cases in recent years. Regardless, this led to a stark decline in the use of and research on tryptophan and 5-HTP supplements. To avoid the risk of EMS, it is important that 5-HTP supplements are purified and tested for contaminants.[1][19]
5-HTP acts as a direct precursor for the neurotransmitter serotonin. 5-HTP readily crosses the blood-brain barrier, which can lead to increased serotonin levels in presynaptic neurons in the brain. This may play a role in regulating mood, sleep, appetite, memory, and various other processes.[4]
However, it’s also important to note that the relationship between serotonin levels and depression is not as clear as many people think. The current body of evidence does not consistently show that lower levels of serotonin are associated with or cause depression.[6]
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