NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated August 1, 2026

Supplement × Supplement·Evidence index

5-HTP and SAMe: what the published research says

PubMed indexes 5 records that name 5-HTP and SAMe together, either in the title or in an interaction, co-administration, or pharmacokinetic context. Each one is listed below with its study design and, where the abstract states one, the authors’ own conclusion, quoted and linked. This page reports that literature. It does not tell you whether to combine them.

Read this first

An evidence index, not guidance.

Every statement below is attributed to a named, dated, linked source.

This page lists published research relevant to 5-HTP and SAMe. It deliberately does not state whether the combination is safe, whether it interacts, in which direction, at what dose, or how far apart to take them.

The research

5 studies naming 5-HTP and SAMe.

Strongest relevance first: papers naming both substances in the title, then human trials and systematic reviews.

L-3,4-dihydroxyphenylalanine and L-5-hydroxytryptophan share the same transporter in Opossum kidney cells.

The international journal of biochemistry & cell biology · 1998 · PMID 9608678

Animal study

“Vmax values (in nmol mg protein-1 6 min-1) for L-5-HTP uptake are identical in the absence (11.2) and the presence of 250 microM L-DOPA (11.7), but K(m) values (microM) are significantly greater (P < 0.05) when L-5-HTP uptake was studied in the presence of L-DOPA (103 vs 220). It is concluded that L-DOPA and L-5-HTP share the same transporter(s) and each compound exerts a competitive type of inhibition upon the other.”

Gomes et al. · From the abstract

Names both 5-HTP and SAMe in its title.

Effect of serotonin on prolactin- and MSH-secreting cells in the eel. Comparison with the effect of 5-hydroxytryptophan.

Cell and tissue research · 1979 · PMID 313251

Comparative StudyAnimal study

“These results suggest that a serotoninergic pathway stimulates PRL and MSH release in the eel. An antagonism between the serotoninergic system and the dopaminergic system previously demonstrated in the same species seems apparent, but the interaction of other organs or factors, such as the pineal, are considered.”

Olivereau et al. · From the abstract

Names 5-HTP and SAMe together in an interaction, co-administration, or pharmacokinetic context.

Limitations

What this evidence cannot tell you.

Search-based evidence indexes have real limits, and it is worth being explicit about them:

NutriStack

Track what you actually take.

NutriStack is a free iPhone app for organising a supplement routine: what you take, when, and what the published record says about it. Its exploratory interaction checker covers 5-HTP, SAMe, and several hundred other substances.

The checker is a research and organisation tool, not a clinical decision aid, and its per-pair assessments are excluded from search until they pass claim-level review.

NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.