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Want to understand how supplement research actually works? These guides will help you read studies, spot junk science, and figure out what’s worth your money.
Start with How We Rate to see our process. Then check out How to Read Supplement Research to build your own skills. If you want to avoid getting scammed, read our Supplement Red Flags guide. And if you’re confused about capsules vs powders vs liquids, we cover that in Supplement Forms Explained.
Got questions? We’ve got answers. Below are the most common things people ask about our ratings and process.
If your question isn’t here, check out How We Rate Supplements for a deep dive into our methodology. You can also reach out through our about page.
Reading supplement research can feel overwhelming. But you don’t need a PhD to spot good studies from bad ones. A few basic concepts will take you most of the way.
RCTs vs. observational studies. Randomized controlled trials (RCTs) are the gold standard. Participants are randomly assigned to take the supplement or a placebo. This controls for other factors that might affect the results. Observational studies just watch what people do naturally. They can show correlations, but they can’t prove a supplement caused anything. When someone says “studies show this supplement works,” ask if those were RCTs or observational. It matters.
Most supplement websites rate products based on opinions, brand deals, or whatever’s trending on TikTok. We don’t do that. Every rating on this site comes from a structured analysis of published research. Here’s exactly how it works.
We follow the same steps for every supplement claim we rate. No shortcuts. No exceptions.
Step 1: Search PubMed for published meta-analyses. We start by looking for existing meta-analyses and systematic reviews on a specific supplement and health claim. These are studies that pool data from multiple randomized controlled trials (RCTs). If a good meta-analysis already exists, we don’t need to start from scratch.
The same ingredient can come in many different forms. And the form you choose can make a huge difference in how well your body absorbs it.
Magnesium is a classic example. Magnesium oxide is cheap and widely available, but your body only absorbs about 4% of it. Magnesium glycinate, citrate, and threonate all have much better absorption rates. If you’re taking magnesium oxide for a deficiency, you’re mostly paying for expensive urine.
Not every supplement is a scam. But plenty of them are. Here are the warning signs that should make you think twice before buying.
Proprietary blends. If a label says “proprietary blend” and lists ingredients without individual doses, that’s a problem. You have no idea how much of each ingredient you’re getting. Companies hide behind proprietary blends when the doses are too low to actually work. Good brands list every ingredient with an exact amount.