The supplement guide rates 30+ popular supplements by evidence tier — from well-established clinical support to marketing-only claims. Filter by your goal to see what the research actually shows. Supplements are not regulated as drugs. Consult a healthcare provider before starting any supplement, especially with existing conditions or medications.
How to Use the Supplement Guide
The supplement industry generates over $40 billion annually in the US alone, largely on products with little or no clinical evidence. Understanding how to evaluate supplement claims helps you spend your money on what works and skip what doesn't.
Step 1: Check if you actually need it
Many people supplement nutrients they already get enough of. Before buying Vitamin D, get a blood test — 40% of Americans are deficient, but 60% are not. Before buying iron, test your ferritin levels. Supplementing adequate nutrients rarely provides benefit and can cause harm at high doses. The same logic applies to zinc, iodine, and most fat-soluble vitamins.
Step 2: Look for third-party testing
Because supplements are not FDA-tested before sale, third-party certification is your best quality indicator. Look for NSF Certified for Sport, Informed Sport, or USP verification on the label. These programs test that the product contains what it claims, at the doses stated, without harmful contaminants or banned substances. This is especially important for athletes subject to drug testing.
Step 3: Use the minimum effective dose
More is not better with supplements. The therapeutic dose of Vitamin D for deficiency is typically 2,000-4,000 IU/day — many people take 10,000+ IU based on wellness influencer advice, which can cause toxicity over time. Creatine's loading protocol (20g/day for 5 days) is optional — 3-5g/day continuously achieves the same saturation in 3-4 weeks with fewer GI side effects. Standard doses from research should be your baseline.
Step 4: Evaluate "proprietary blends" skeptically
Many supplements combine multiple ingredients in a "proprietary blend" where individual doses are hidden. This often means each ingredient is included in sub-therapeutic amounts (too little to have any effect) purely so it can appear on the label. If a pre-workout blend contains 30 ingredients, each is almost certainly below the dose shown to be effective in clinical trials. Single-ingredient supplements at research doses are almost always preferable.
FAQ
Is this supplement guide free?
Yes, completely free with no signup required.
Is my data private?
Yes. No data is sent to any server. Everything runs locally in your browser.
Are supplements regulated by the FDA?
No — supplements are regulated very differently from drugs. Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, supplement manufacturers do not need to prove their products are safe or effective before selling them. The FDA only intervenes after a product causes harm. This means claims like 'boosts immunity' or 'supports cellular health' require no clinical proof. The FTC regulates advertising claims, which is why you see qualifiers like 'may help' or 'some studies suggest.'
What does 'strong evidence' mean in this guide?
Strong evidence means the supplement's primary claimed benefit is supported by multiple randomized controlled trials (RCTs) that are large enough to detect real effects, peer-reviewed and published in credible journals, replicated by independent research teams, and showing consistent results rather than mixed findings. Creatine monohydrate and caffeine meet this standard for their performance claims. Melatonin meets it for sleep timing. Many popular supplements do not.
Is creatine safe?
Creatine monohydrate is one of the most studied supplements in sports science, with decades of research showing safety in healthy adults at standard doses (3-5g/day). Contrary to gym myths, creatine does not cause kidney damage in healthy people. The most common side effect is water retention (1-3 lbs) during loading phase. It is not recommended for those with pre-existing kidney disease. The cheapest form (creatine monohydrate powder) is the most studied and effective — premium forms (creatine HCl, ethyl ester) have no evidence of superiority.
Who should take Vitamin D supplements?
Vitamin D deficiency is common — estimates suggest 40%+ of Americans have insufficient levels, particularly in northern states, dark-skinned individuals (melanin reduces UV absorption), people with limited sun exposure, and the elderly. The best way to know is a blood test. If you are deficient (below 20 ng/mL), supplementation has strong evidence for preventing deficiency-related health issues. Whether high-dose supplementation benefits people who are NOT deficient is less clear — research is ongoing.