The evidence-based supplement reference
Know what to take, how much you need,
and how much is too much.
Plain-English monographs and sourced guides for 57 vitamins, minerals and supplements. Every figure traceable to the NIH Office of Dietary Supplements. We sell nothing and recommend no brands.
Sourced, practical guides
Decision guides that lead with the evidence, colour-coded by what they cover.
Magnesium forms compared: glycinate, citrate and oxide
A plain-language look at how the three most common supplemental magnesium forms differ in absorption, tolerability, and practical use.
SleepThe best-evidenced supplements for sleep, ranked by the research
A plain-language look at what the science actually says about melatonin and magnesium for sleep, graded by evidence strength.
HerbalsDo probiotics actually work? What the evidence really supports
Some uses have solid research behind them, others much less so - here is what the science actually says.
InteractionsSupplements that interact with blood thinners
Vitamin K, omega-3 fatty acids, and ginkgo biloba can all affect how anticoagulant medications work, so timing and dosage deserve careful attention.
MineralsIron and vitamin C: the absorption pairing that actually helps
Eating vitamin C alongside plant-based iron sources is one of the few nutrition pairings backed by strong evidence from the NIH Office of Dietary Supplements.
DosingHow much vitamin D per day, by age, pregnancy and 50+
A plain-language breakdown of NIH recommended intakes, upper limits, and what the evidence actually says about vitamin D.
Browse the spectrum
57 monographs across four families, each with the daily target, the safe ceiling and cited sources.