About smile
The most trusted supplement directory, built on science.
Every supplement profile in smile is built from peer-reviewed research. We grade each health claim using a transparent A-D evidence scale based on the quality, quantity, and consistency of available clinical studies.
AGrade A: Strong evidence from multiple high-quality RCTs
BGrade B: Good evidence from well-designed studies
CGrade C: Moderate evidence, more research needed
DGrade D: Limited or preliminary evidence only
We primarily reference studies indexed in PubMed, data from the NIH Office of Dietary Supplements, and systematic reviews from the Cochrane Library. Every claim links back to its source.
smile is not sponsored by any supplement brand. Our evidence grades and recommendations are based solely on published research. We may earn affiliate commissions when you purchase products through our links, but this never influences our ratings or rankings.