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

Supplement × Supplement·Evidence index

L-Tryptophan and Vitamin B3: what the published research says

PubMed indexes 8 records that name L-Tryptophan and Vitamin B3 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 L-Tryptophan and Vitamin B3. 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

8 studies naming L-Tryptophan and Vitamin B3.

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

Organ Co-Relationship in Tryptophan Metabolism and Factors That Govern the Biosynthesis of Nicotinamide from Tryptophan.

Journal of nutritional science and vitaminology · 2018 · PMID 29710037

ReviewHuman subjects

“Studies on factors have shown that conversion of Trp to nicotinamide is increased by adequate intake of good quality protein, and adequate intake of unsaturated fatty acids and starch. However, conversion was decreased by deficient niacin, vitamin B2, or vitamin B6, excessive intake of protein, saturated fatty acids, or glucose and fructose, or intake of protein with low Trp content, and insufficient mineral intake.”

Shibata · From the abstract

Names both L-Tryptophan and Vitamin B3 in its title.

Insulin resistance and dysregulation of tryptophan-kynurenine and kynurenine-nicotinamide adenine dinucleotide metabolic pathways.

Molecular neurobiology · 2013 · PMID 23813101

Research Support, N.I.H., ExtramuralReviewHuman subjects

“Monitoring of KYN/P5P status and formation of XA might help to identify subjects at risk for IR. Pharmacological regulation of the TRP-KYN and KYN-NAD pathways and maintaining of adequate vitamin B6 status might contribute to prevention and treatment of IR in conditions associated with inflammation/stress-induced excessive production of KYN and deficiency of vitamin B6, e.g., type 2 diabetes, obesity, cardiovascular diseases, aging, menopause, pregnancy, and hepatitis C…”

Oxenkrug · From the abstract

Names both L-Tryptophan and Vitamin B3 in its title.

Tryptophan-niacin relationship in Xanthomonas pruni.

Journal of bacteriology · 1963 · PMID 14001084

“The results confirm the conclusion, drawn from growth studies, that niacin is needed to permit tryptophan synthesis at a sufficient rate to promote growth. In the absence of an external source of niacin, tryptophan or some of its metabolites can promote growth by acting as precursors of niacin.”

WILSON et al. · From the abstract

Names both L-Tryptophan and Vitamin B3 in its title.

Neuronutrients and Central Nervous System: A Systematic Review.

Central nervous system agents in medicinal chemistry · 2023 · PMID 36411563

Systematic ReviewHuman subjects

“The areas of neurology and psychiatry have shown great advances regarding the deepening of knowledge in prophylaxis and pathophysiology, as well as in the treatment of established diseases. The recognition of the role of nutrition as an adjunct to these processes is currently growing. The search in scientific bases for neuro nutrients reveals a great growth of publications related to this theme.”

Nogueira-de-Almeida et al. · Authors' conclusion

Names L-Tryptophan and Vitamin B3 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 L-Tryptophan, Vitamin B3, 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.