Methodology
Transparency is core to what we do. This page explains exactly how we grade evidence, what factors go into the score, and what the grades mean and don't mean.
The research pipeline
Our automated pipeline scans PubMed, bioRxiv, and medRxiv daily for new research relevant to supplements, habits, and health protocols. We process hundreds of papers per month, extracting specific claims, effect sizes, and study details.
Evidence grades: S to D
Every supplement and habit receives a grade based on the quality and quantity of available research. Here's what each grade means and what it takes to earn it.
Scoring factors
Grades aren't assigned by gut feeling. Every supplement's grade is derived from a weighted assessment of these factors across all studies we track.
| Factor | Weight | What we look at |
|---|---|---|
| Study type | High | Meta-analyses and systematic reviews carry the most weight, followed by randomized controlled trials, then cohort studies. Animal and lab studies inform our understanding but don't drive grades. |
| Sample size | High | Larger studies are more reliable. A study with 2,000 participants tells us more than one with 20. We look at combined sample sizes across all available studies. |
| Replication | High | Has the finding been reproduced by independent research groups? A single study, no matter how large, is less convincing than the same result found by multiple teams. |
| Effect size | Medium | How large is the actual benefit? A statistically significant but tiny effect matters less than a meaningful, noticeable improvement. |
| Study quality | Medium | We assess blinding, randomization, control groups, dropout rates, and potential conflicts of interest. Industry-funded studies aren't excluded but are noted. |
| Consistency | Medium | Do the studies agree? If 8 out of 10 studies show the same direction of effect, that's more convincing than a 5-5 split. |
| Publication bias | Low | Positive results are more likely to be published than negative ones. We try to account for this by looking at registered trials that may not have published results. |
| Population relevance | Low | Studies on healthy adults are weighted more for general recommendations. Studies on specific clinical populations are noted but don't automatically generalize. |
What grades don't mean
A grade is not a recommendation. A supplement with an S grade has strong research behind it, but that doesn't mean you specifically need it. Your diet, health status, medications, and goals all matter.
A low grade doesn't mean "bad." A B grade often just means "not enough research yet." Many promising supplements start at B and move up as more studies are published. The grade reflects the evidence, not the potential.
Grades change. When new research publishes, grades update. A supplement at A today could move to S or drop to B depending on what future studies find. That's the point. We follow the evidence, not the hype.
From research to protocol
Individual evidence claims are aggregated per supplement and habit, producing an overall evidence grade. Protocols are then assembled by combining interventions that target specific goals, with each step showing the evidence grade of its underlying research. Protocol-level grades represent the average strength of evidence across all steps.
Editorial review
While our pipeline is automated, all published content undergoes human review before reaching the site. AI-generated content is marked as such and reviewed for accuracy, tone, and medical appropriateness.
Affiliate policy
Affiliate commissions never influence evidence grades. We recommend what the science supports, then find the best product for that recommendation. Evidence grades are derived from published research and are never adjusted based on commercial partnerships.