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5-HTP

Supplement amino acid derivative sleepbrain & mood
Aka: 5-hydroxytryptophan, oxitriptan, Griffonia simplicifolia
Brands seen in Singapore: California Gold Nutrition, NOW Foods, Nutricost, Swanson Vitamins, Thorne
Third-party tested: Thorne certifies other products with NSF Certified for Sport, but nothing for 5-htp.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Limited human evidence — sleep trials are small and old
Studied for
The Singapore RCT used 100 mg daily for 12 weeks
Pros & cons
Pros
  • SG 12-week RCT: poor sleepers improved on the psqi
  • Main natural source is griffonia simplicifolia seed
  • No definitive toxicity cases in ~20 years of use
Cons
  • Sleep trials are small, old and often uncontrolled
  • Nausea and vomiting reported at doses above 100 mg
  • Peak x contaminants found in commercial 5-HTP samples
Sources
  1. 5-Hydroxytryptophan (5-HTP): Natural Occurrence, Analysis, Biosynthesis, Biotechnology, Physiology and Toxicology (Maffei, Int J Mol Sci 2021;22(1):181) — s8.2.3 Effect of 5-HTP on Sleep Disorders · read 2026-08-27
    what it says
    “In normal subjects treated with 5-HTP, rapid eye movement (REM) sleep increased from 5 to 53% of placebo baseline … the effects on sleep were associated with different doses of 5-HTP and the diverse possibilities of metabolic transformation”
  2. Maffei, Int J Mol Sci 2021 (same review) — s8.2.1 Serotonin Syndrome · read 2026-08-27
    what it says
    “Medication-induced serotonergic hyperactivity causes serotonin syndrome, which results from antidepressant medications and is characterized by the triad of altered mental status, autonomic dysfunction, and neuromuscular abnormalities … Excessive 5-HTP stimulation is the main pathophysiologic mechanism involved”
  3. Maffei, Int J Mol Sci 2021 (same review) — s8.2.2, dose-related side effects · read 2026-08-27
    what it says
    “… 5-HTP may cause dose-dependent gastrointestinal problems … vomiting and nausea have been reported when 5-HTP was used at doses above 100 mg”
  4. Maffei, Int J Mol Sci 2021 (same review) — s8.2.2, combination with a peripheral decarboxylase inhibitor (carbidopa) · read 2026-08-27
    what it says
    “the combination of 5-HTP with a peripheral decarboxylase inhibitor may cause psychopathological side effects, like acute anxiety”
  5. Maffei, Int J Mol Sci 2021 (same review) — s9 toxicology / peak X contaminants · read 2026-08-27
    what it says
    “no definitive cases of toxicity have emerged despite the worldwide usage of 5-HTP for the last 20 years … samples of commercially available 5-HTP analyzed by HPLC-MS contained three or more contaminants of the peak X family”
  6. Maffei, Int J Mol Sci 2021 (same review) — s10 Conclusions, natural source · read 2026-08-27
    what it says
    “The main natural source of 5-HTP is the seeds of the African plant Griffonia simplicifolia”
  7. The impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: A randomized controlled trial (Clin Nutr 2024;43, doi 10.1016/j.clnu.2024.01.010; NCT04078724) — Singapore, n=30, single-blinded · read 2026-08-27
    what it says
    “Thirty older adults (66 ± 3 years) in Singapore were randomly assigned to either consume or not consume 100 mg 5-HTP daily … at week 12 … poor sleepers with 5-HTP supplementation were able to significantly improve subjective GSS”
  8. Effects of 5-hydroxytryptophan on distinct types of depression: a systematic review and meta-analysis (Javelle et al., Nutr Rev 2020;78(1); PROSPERO CRD42018104415) — 13 studies reviewed, 7 meta-analysed · read 2026-08-27
    what it says
    “the OHAT (Office of Health Assessment and Translation risk of bias rating) tool suggested that, on the whole, current studies are relatively weak (few include placebo groups) … Methodological variability … contributes to heterogeneity in the results”
  9. HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in HS and TM, GL-CHPB-1-012 (October 2025), Annex B row 4 (L-tryptophan). 5-HTP itself is NOT listed in Annex A or Annex B · read 2026-08-27
    what it says
    “L-tryptophan — Known to interact with serotonergic antidepressants, e.g. SSRIs, MAOIs and might increase the risk of serotonergic side effects including serotonin syndrome … Known to interact with sedative medications, e.g. clonazepam, lorazepam”
  10. HSA Singapore — Health Supplements Guidelines (January 2026), s4.8 and Tables 4–5 (vitamins and minerals only) · read 2026-08-27
    what it says
    “4.8 HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5”
  11. HSA Singapore — Health Supplements Guidelines (January 2026), s6.6 and Table 6, prohibited claims (depression named under brain and nervous system) · read 2026-08-27
    what it says
    “HS must not be labelled, advertised or promoted for any specific medicinal purpose, i.e. treatment or prevention, implied or otherwise, of any disease or disorder … Brain and nervous system: Epilepsy … depression, eating disorders”
  12. iHerb Singapore — 5-HTP category page, default (best-selling) order, SGD pricing · read 2026-08-27
    what it says
    “California Gold Nutrition, 5-HTP, 100 mg … NOW Foods, 5-HTP, 100 mg … Nutricost, 5-HTP, 200 mg … Swanson Vitamins, 5-HTP, 100 mg … Thorne, 5-Hydroxytryptophan, 90 Capsules”
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Updated 2026-08-30. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.