5-HTP after Korea's overseas-supplement crackdown: what MFDS found, and what the sleep and mood evidence actually shows

In late October 2026, South Korea's Ministry of Food and Drug Safety (MFDS) and the Korea Consumer Agency checked 60 overseas direct-purchase supplements marketed for "focus" or "height growth". Thirty-seven of the 60 carried or contained ingredients Korea blocks from food imports. Height-growth products commonly listed or found to contain 5-hydroxytryptophan (5-HTP), which Korea treats as a blocked, prescription-class ingredient for food.

5-HTP is also sold in many other countries as a sleep and mood supplement, often from Griffonia simplicifolia seeds. The evidence for those uses is thin, and combining it with serotonergic medicines carries a real interaction warning.

The short answer: Korea's joint check found hazardous or blocked ingredients in 37 of 60 focus and height products, with 5-HTP a recurring problem in height-growth SKUs. That is a regulatory fact about Korean food import rules, not proof that 5-HTP "works" for growth. For sleep and depression, the human evidence is small, older and methodologically weak. Memorial Sloan Kettering warns patients on SSRIs, MAOIs, tricyclics or other serotonergic drugs to avoid 5-HTP without physician supervision because of the theoretical potential for serotonin syndrome, a serious condition.

What Korea found in October 2026

Yonhap reported on 29 October 2026 (AKR20261028128300030) that the Korea Consumer Agency and MFDS surveyed 60 overseas direct-purchase foods sold online for concentration or height growth. Hazardous or import-blocked ingredients were labelled or detected in 37 products (61.7%): 18 of 30 focus products and 19 of 30 height products.

• Focus products: labels named bacopa, deanol and L-dopa; laboratory testing detected vinpocetine and kava in some products. Yonhap notes vinpocetine and L-dopa as prescription medicine ingredients, and warns that unsupervised use in children or adolescents can cause sleep problems or nerve-cell injury.
• Height products: labels or tests involved 5-HTP, melatonin, citrulline and dolomite. New Era Korea Daily's English summary of the ministry notice says 5-HTP was detected in six height products and melatonin in one, and that some labels did not match what was found in the bottle.
• MFDS asked customs to hold the products, asked communications regulators to block sales sites, and asked for action against purchasing-agent businesses. Product details were posted on the ministry's overseas direct-purchase hazardous-food list. New Era cites 5,048 products on that list as of 26 October 2026.

MFDS's official "Overseas Direct-Purchase Food, Rightly" / Allbaro pages are the live lists to check before buying. A separate Food Safety Korea catalogue of ingredients blocked for internet purchasing-agent import (basis date 25 August 2021) lists "5-HTP (5-hydroxytryptophan), Griffonia, Griffonia simplicifolia seed extract" as item 1. In Korea, that is a food-import block, not a statement about efficacy for sleep or mood.

What 5-HTP is

5-HTP is an intermediate on the path from the amino acid tryptophan to serotonin and melatonin. Supplement products are commonly made from Griffonia simplicifolia seeds. Memorial Sloan Kettering's About Herbs monograph summarises the rationale: raise serotonin where it may be low. That is a mechanism story. It is not the same as proven clinical benefit.

Depression evidence

A 2020 systematic review and meta-analysis in Nutrition Reviews (Javelle and colleagues) included 13 investigations in the qualitative review and seven in the full meta-analysis. It reported a depression remission rate of 0.65 (95% CI 0.55 to 0.78) and a large Hedges' g of 1.11 (95% CI 0.53 to 1.69) on questionnaire scores. The same paper flags high heterogeneity (I² = 76%), wide variation in dose, duration, depression type and design, and an Office of Health Assessment and Translation (OHAT) risk-of-bias rating that current studies are relatively weak, with few placebo groups. The authors ask for better placebo-controlled trials in well-defined depression.

The Cochrane review of tryptophan and 5-HTP for depression (Shaw, Turner and Del Mar, 2002) found only two trials of sufficient quality to include, with 64 patients in total. One trial studied 5-HTP and the other studied tryptophan; Cochrane pooled them. Those trials suggested benefit versus placebo (Peto odds ratio 4.10; 95% CI 1.28 to 13.15), but the reviewers called the evidence of insufficient quality to be conclusive and said further studies were needed before widespread use could be recommended.

Sleep evidence

A 2024 single-blind randomised controlled trial in Clinical Nutrition enrolled 30 older adults in Singapore (mean age 66), assigned to 100 mg of 5-HTP daily or no capsule (not a placebo) for 12 weeks (NCT04078724). The authors report a favourable effect on certain sleep-quality components, a rise in serum serotonin, and clearer subjective global sleep-score improvement among participants who started as poor sleepers. Thirty people is a small sample. It is not a large, multi-centre demonstration that 5-HTP fixes insomnia.

Safety and drug interactions

Memorial Sloan Kettering warns that patients taking selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants or other drugs that affect serotonin should avoid 5-HTP without physician supervision because of the theoretical potential for serotonin syndrome, a serious condition. The same monograph advises against combining 5-HTP with St John's wort or SAM-e for the same reason, notes common gastrointestinal side effects, and cites case reports including mania with an MAOI, serotonin syndrome with linezolid, and a scleroderma-like illness with carbidopa plus 5-HTP. Common side effects listed there include nausea, vomiting or diarrhoea; less common ones include headache, insomnia and palpitations.

Yonhap also notes Korea Consumer Agency advice that 5-HTP can cause blood-pressure changes and gastrointestinal problems. None of that makes 5-HTP appropriate as a "height growth" food for children.

How to read the marketing

Two separate facts are being mixed in the news cycle. Korea blocked many overseas focus and height products because they listed or contained ingredients that are not allowed in Korean food imports, including 5-HTP. Separately, 5-HTP is sold elsewhere for sleep and mood on evidence that systematic reviewers themselves call weak or inconclusive. A customs hold in Seoul does not prove the ingredient is dangerous in every legal market, and a serotonin mechanism does not prove it treats depression or insomnia. Honest labelling would say the human evidence is limited, interactions with antidepressants matter, and "height growth" claims for a serotonin precursor are not supported by the Korean regulatory action or by the sleep and depression literature summarised here.

South African rules

SAHPRA's public information states that, under the Medicines and Related Substances Act 101 of 1965, any product intended to treat, prevent or alter bodily functions must be registered with SAHPRA before it can be sold in South Africa. A product sold on depression, insomnia or height-growth medicinal claims belongs under that scrutiny. Side effects can be reported to adr@sahpra.org.za.

FAQ

Why did Korea block 5-HTP products?

MFDS treats 5-HTP and Griffonia seed extract as ingredients subject to import block for food, and the October 2026 joint check found 5-HTP labelled or detected in height-growth overseas products. Check the official hazardous-food list and Allbaro before buying products shipped into Korea.

Does 5-HTP treat depression?

The evidence is limited and often low quality. A 2020 meta-analysis reported large average effects but high heterogeneity and few placebo controls. Cochrane in 2002 found only two adequate trials. Depression needs proper medical assessment; do not replace prescribed care with a supplement.

Does 5-HTP improve sleep?

One 2024 randomised trial in 30 older adults in Singapore reported improvement in certain sleep-quality measures, especially in people who began as poor sleepers. That is early evidence, not a definitive insomnia treatment.

Can I take 5-HTP with an antidepressant?

Memorial Sloan Kettering advises people on SSRIs, MAOIs, tricyclics or other serotonergic drugs to avoid 5-HTP without their physician's supervision because of the theoretical potential for serotonin syndrome, a serious condition. Ask a doctor or pharmacist before combining them.

Where can I report a suspicious product in South Africa?

SAHPRA asks the public to report suspected illegal sales through its 24-hour hotline on 0800 204 307, and side effects to adr@sahpra.org.za.