About SupplementDuel

SupplementDuel is a free tool for comparing supplements side by side. We compile supplement data from peer-reviewed research, the NIH Office of Dietary Supplements, PubChem, and consensus from independent analysts (e.g. Examine.com summaries), and lay it out in a single tidy comparison table covering dosing, evidence quality, effects, side effects, drug interactions, and price.

We rate evidence on a four-tier scale (strong → moderate → limited → preliminary) based on the quantity and quality of randomized human trials. Effect ratings (1–5) reflect the magnitude of effect observed in the highest-quality trials available, not what's claimed on a label.

We are independent and not owned by any supplement brand. We may earn a commission when you buy a product through a partner retailer (currently iHerb). This never influences our ratings — affiliate links go to whatever brand the user picks once they're on iHerb.

This is not medical advice. Information on this site is for general education only. Individual responses to supplements vary, and interactions with prescription medication can be serious. Always consult a qualified physician, registered dietitian, or pharmacist before starting, stopping, or combining supplements — especially if you are pregnant, breastfeeding, taking prescription medication, or managing a chronic condition.