Honest, independent supplement evidence — free for everyone.

SupplementScore is a free, public reference that grades dietary supplements against published clinical trials. Every score traces back to peer-reviewed research. No sponsorships, no affiliates, no ads. This page covers who we are, how scoring works, and the policies that keep the calls honest.

Why we exist

The right supplement can genuinely change someone's life — better sleep, less joint pain, more energy, fewer migraines. The wrong one can drain a wallet, interact with a prescription, or harm an organ. But finding honest information is nearly impossible. The supplement industry generates over $50 billion a year in the US alone, and most of what you read online is written by someone trying to sell you something.

We built SupplementScore to fix that. The long-term goal is to use the best of clinical evidence, and eventually blood work and DNA, to curate precise, personalized supplement guidance for each individual. We don't sell supplements. We don't accept sponsorships. We don't run affiliate links. SupplementScore is, and will remain, free.

The four evidence tiers

Every supplement on the site is placed in one of four tiers. The tier is the headline call: how confident the evidence is, and what kind of risk profile the supplement carries.

The six sub-scores

Each supplement carries six 1–5 sub-scores. They roll up into the headline 0–100 score shown on the card, with efficacy and safety weighted highest. The sub-scores let you see why a supplement scores the way it does, instead of treating the headline as a black box. The exact formula lives in app.js under calcScore and is open for inspection.

How tiers move

Tier is a function of the composite score and a citation gate. A high score alone is not enough for Tier 1; a low score alone is not enough to demote from Tier 1. A supplement only moves between tiers when both conditions for the new tier are satisfied at the same time:

• Score band. The composite must fall inside the new tier's range (T1 ≥72, T2 60–71, T3 40–59, T4 <40).
• Citation gate (T1 only). At least one pivotal PubMed-indexed study with a public or nonprofit funder.
• Safety floor (T1 + T2 only). No active FDA / EFSA / TGA / Health Canada warning that renders the supplement inappropriate for the general adult population.
• Replication (T1 only). The pivotal effect has been seen in at least two independent samples — not necessarily two trials, but two analyses that don't share a single research group's data.

Safety-driven moves are an exception: if a major regulator issues a contraindication or recall, the supplement moves to T4 within one deploy cycle regardless of efficacy score. In the prior 12 months: 12 net promotions, 4 demotions, and 1 safety-driven move. The full audit trail lives in _archive/score-changes.csv.

Where the evidence comes from

Not all citations are equal. Where multiple sources speak to a single claim, the stronger evidence type carries more weight in the score. The order below is how we resolve disagreements between sources:

1. 01Meta-analyses & Cochrane systematic reviewsPooled effect, risk-of-bias graded
2. 02Regulator dossiersFDA / EFSA / EMA / NIH ODS / Health Canada
3. 03Independently-funded RCTsDirect evidence in humans
4. 04Cohort & observational studiesUseful for safety signals
5. 05Mechanistic, animal, or anecdotalHypothesis-generating only

The primary sources every score draws from include PubMed, the Cochrane Library, ClinicalTrials.gov, NIH Office of Dietary Supplements, NCCIH, EFSA, EMA HMPC, Health Canada NNHPD, openFDA FAERS, FDA MedWatch, WHO monographs, USDA FoodData Central, DrugBank, the USPSTF, and top-tier journals (NEJM, Lancet, JAMA, BMJ, AJCN, JISSN). Critical-appraisal frameworks include GRADE, Cochrane RoB 2, AMSTAR-2, CONSORT, and PRISMA. The complete registry of 61 sources is in sources/registry.json; browse the bibliography →

What we explicitly do not use as primary sources: manufacturer literature, affiliate-driven supplement review sites, nutritional industry trade publications, celebrity-endorsed product pages, retailer product pages, multilevel-marketing materials, and influencer or podcast claims. They may appear in an article only as evidence of a marketing claim being analysed.

Funding policy

Industry-funded supplement trials report effect sizes ~20–30% larger on average than independently-funded ones, after controlling for design quality. We don't pretend this away.

• Every cited study is tagged with funder, funder type (public, industry, mixed, nonprofit, none_disclosed), and a competing-interest flag.
• When pooled effect sizes come from industry-funded trials, we apply a ~25% downward adjustment in the narrative. The adjustment is documented per supplement.
• A Tier 1 call requires at least one public or nonprofit-funded confirmatory study. Industry-only evidence cannot promote a supplement to Tier 1.
• Citations visually flag industry funding (amber) and competing-interest disclosures (red) so readers can weigh them themselves.

Why 25% and not 0%: industry-funded trials are not worthless. Many are well-designed and add real evidence. We discount rather than discard. The number is a judgment call drawn from meta-research on funding bias; we'll revise as our own tracking accumulates.

Our own COI policy: SupplementScore is operated as a non-profit. We accept no funding from manufacturers, distributors, retailers, or affiliate programs. We do not run advertising. Hosting and tooling are paid from individual reader donations and the operator's personal funds. Editorial staff disclose any holdings (equity, consulting, speakerships) related to the supplement industry within the prior three years; anyone with active industry ties cannot author or second-read entries where the conflict applies.

Review cadence

Different content carries different stakes. We review accordingly:

If FDA MedWatch or EFSA publishes an alert for a supplement we track, it jumps the queue regardless of its last-reviewed date. Every supplement card and article shows its Last reviewed date so readers can see how fresh the call is.

How interactions are modeled

The interactions system is built on three pieces. Pairs capture explicit positive synergies — vitamin D3 + K2 for bone density, iron + vitamin C for absorption — each with a 1–5 strength rating. Cautions capture explicit negative pair interactions with severity: either caution (additive risk that warrants attention) or avoid (combinations to skip). St. John's Wort + SSRIs is an avoid for serotonin syndrome; ashwagandha + thyroid medication is a caution. Mechanism groups bundle supplements that share a pathway (bleed, serotonin, sedation, stimulant, hepatotoxic, hypoglycemic, hypotensive, thyroid modulator, and others) and auto-flag any two members against each other.

When you build a stack in your profile, the system flags conflicts in three places: a chip on each card, a grouped row inside the card describing the mechanism, and a top-of-plan banner enumerating every conflict. Drug-supplement interactions are a separate parallel system, currently in build-out as Phase 2 of the roadmap.

Roadmap

Four stages toward hyper-personalized supplement recommendations.

What we don't claim

Specifically, we do not diagnose conditions or recommend supplements as treatment for a diagnosed condition, provide individualised dosing (the doses shown are population-level ranges from clinical trials), replace pharmacist or physician review of supplement-medication interactions, endorse specific brands, or claim that any supplement prevents, treats, or cures any disease.

Scores reflect group-level clinical data; individual responses vary by genetics, diet, health status, medications, and pre-existing conditions. Supplement quality varies dramatically between brands — we do not test, certify, or endorse specific products. Always consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you are pregnant, nursing, or on medications. In a medical emergency, contact your local emergency services immediately.

Glossary

Plain-language definitions for the research terms used across the site. If you've ever wondered what "p < 0.05" means or what "GRADE" actually grades, this is for you.

Flag an error

If you spot an inaccurate claim, click the Flag inaccuracy button on the affected article or supplement card. The form asks for three things: the claim you think is wrong, what you think it should say, and a citation URL (PubMed, DOI, regulator dossier, or peer-reviewed paper).

The citation is required up front because it turns reader feedback into a signal we can act on. Every submission with a citation gets triaged. Submissions touching Tier 4 safety or drug interactions are escalated to same-day review — wrong information about high-stakes content is the highest-liability content on the site, and we treat it that way.