5-HTP
Serotonin precursor that supports mood, sleep and appetite
What is 5-HTP?
5-Hydroxytryptophan (5-HTP) is an amino acid that the body produces from tryptophan (found in turkey, eggs, cheese, and oats). It is the direct precursor to serotonin — crossing the blood-brain barrier and converting to serotonin in the brain. Unlike tryptophan, 5-HTP does not compete with other large neutral amino acids for transport across the blood-brain barrier, making it a more reliable way to increase central serotonin levels. It is extracted commercially from the seeds of Griffonia simplicifolia.
How it works
5-HTP is converted to serotonin (5-hydroxytryptamine, 5-HT) by the enzyme aromatic amino acid decarboxylase (AADC), using vitamin B6 as a cofactor. Serotonin is then converted to melatonin (by N-acetyltransferase and HIOMT) in the pineal gland during darkness. By providing direct precursor to both serotonin and melatonin, 5-HTP can influence mood, appetite (serotonin activates satiety centres), sleep onset, and pain modulation.
What the evidence shows
Mood/depression: A 2002 Cochrane review found 5-HTP superior to placebo for depressive symptoms in preliminary trials, but noted methodological limitations. Italian trials in the 1990s showed benefits comparable to some antidepressants. Sleep: 5-HTP combined with GABA or L-theanine improves sleep quality in RCTs. Fibromyalgia: multiple trials show pain and fatigue improvement. Appetite: 5-HTP consistently reduces calorie intake (by 200–400kcal/day) and promotes satiety in RCTs. Evidence is at level 3 — promising but not as extensive as the previous ingredients.
When to expect results
Sleep onset improving if taken before bed. Dreams may become more vivid — this is normal with serotonin/melatonin elevation.
Mood stabilising. Appetite decreasing noticeably — feeling full sooner. Carbohydrate cravings reducing.
Consistent mood elevation in those with low baseline serotonin. Sleep quality sustained. Energy levels improving.
Consider cycling — use 5-HTP for 6–8 weeks then take a break (2–4 weeks) to prevent receptor downregulation.
Dosing
50–300mg daily. For sleep: 100–200mg 30–60 minutes before bed. For mood: 50–100mg two to three times daily with meals. Start with the lowest dose and increase gradually. Do not exceed 400mg/day from supplements without medical supervision. Always take with vitamin B6 (aids conversion to serotonin).
Forms to choose
5-HTP capsules (Griffonia simplicifolia seed extract) are the standard form. Available in doses of 50mg, 100mg, and 200mg. Some products combine 5-HTP with L-theanine and magnesium (sleep formulas) or with B6. Time-release formulations are marketed but limited evidence for superiority.
Who benefits most
People with low mood who are not on antidepressant medication, those with poor sleep and racing thoughts, people trying to manage appetite and calorie intake, individuals with fibromyalgia or chronic pain, and those with low serotonin symptoms (cravings, irritability, low mood in winter).
Who should avoid / caution
Anyone on SSRIs, SNRIs, MAOIs, tramadol, or other serotonergic medications (risk of serotonin syndrome — a potentially serious condition). People with bipolar disorder (may worsen mania risk). Pregnant or breastfeeding women. Those with Down syndrome (may alter platelet function). Do not combine with carbidopa.
Interactions & stacking
SERIOUS: combining 5-HTP with SSRIs, SNRIs, MAOIs, or tramadol risks serotonin syndrome. Do not combine without specialist supervision.
B6 is the cofactor for the enzyme that converts 5-HTP to serotonin. Ensure adequate B6 intake to maximise conversion.
L-Theanine moderates the anxious edge some people experience on 5-HTP alone. Good sleep formula combination.
5-HTP is a melatonin precursor. Combining both may be excessive for sleep onset — choose one or start with low doses of each.
Safety & side effects
GI effects (nausea, vomiting, diarrhoea) are the most common side effects, especially at higher doses or on an empty stomach — take with food. The 'serotonin syndrome' risk is a real concern when combining 5-HTP with other serotonergic drugs — see interactions. Cardiac valve concerns were raised in historical case reports at very high doses (above 6–900mg) over extended periods — stay within recommended doses and cycle off periodically.
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This information is for educational purposes only and does not constitute medical advice. Always consult your GP or a qualified healthcare professional before starting any new supplement, particularly if you are pregnant, breastfeeding, have a medical condition, or are taking prescription medication.