The supplement guide: the short list worth paying for

The questions people actually bring us.

Q01

What supplements are actually worth taking?

For a general-population adult, the short list is small. Creatine monohydrate (3-5 g/day) is the most replicated performance supplement (Kreider et al. 2017, J Int Soc Sports Nutr); see our explainer on what creatine does and the dosing page on how much to take, then the $/g comparison best-creatine-monohydrate. Vitamin D3 is worth it only to correct a measured deficiency: see what vitamin d does and how much vitamin d per day, then best-vitamin-d. Omega-3 (EPA+DHA) is worth it if you eat oily fish under ~2x/week (Mozaffarian 2006, JAMA): see what omega-3 does, then best-fish-oil. Protein powder is a cheap complete-protein food: see best-protein-powders. Everything else is goal-specific or skippable.

Q02

How do you decide whether a supplement earns its cost?

Two filters, in order. First, evidence grade: is there replicated human RCT data for the endpoint you care about, or just mechanistic and marketing claims? We tag every supplement review with an A-F evidence tier. Second, cost per effective dose: not the bottle price, but the price per gram of the active ingredient at the dose the trials used. A $40 bottle delivering 60 effective doses beats a $20 bottle delivering 20. Every comparison on this site carries a $/g or $/serving column for exactly this reason. A supplement passes only if it clears both filters: real evidence for your goal, and competitive unit economics.

Q03

Do I need a multivitamin?

For most people eating an adequate, varied diet, no. The large multivitamin trials (Physicians' Health Study II, Sesso et al. 2012; the COSMOS-Mind cognition data) show small or no all-cause benefit in well-nourished populations. The multivitamin is insurance against gaps, not a performance lever. It earns a place only when intake of a specific nutrient is genuinely constrained (restrictive diet, malabsorption, life stage). The higher-yield move is to identify the one or two nutrients you are actually short on (often vitamin D, sometimes magnesium or omega-3) and dose those specifically. See best-multivitamin-2026 for when the insurance case holds and which formulas avoid the megadose-and-binder problem.

Q04

Which supplements are the biggest waste of money?

The ones sold on mechanism without human outcome data at a realistic dose. The recurring offenders: testosterone boosters, most fat burners (caffeine plus filler), proprietary blends that hide per-ingredient doses (you cannot dose what you cannot see), greens powders priced at 10-20x the produce they claim to replace, and any product whose marketing leans on a single rodent study. The tell is always the same: strong claim, weak evidence tier, and no published per-serving cost of the active ingredient. When a label hides the dose behind a proprietary blend, treat the whole product as unpriceable and skip it.

Q05

In what order should I add supplements?

Goal-first, cheapest-effective-first. If the goal is strength or training output, start with adequate protein (food first, then powder for the gap) and creatine, the two with the best evidence-to-cost ratio. If a blood test shows low vitamin D, correct that next. If you eat little oily fish, add omega-3. Only then consider the Tier B items (magnesium for sleep or low intake, electrolytes for heavy sweat loss). Add one item at a time, hold it for 8-12 weeks, and judge it against a measurable endpoint. A stack of ten supplements you cannot evaluate is worse than three you can.

Q06

Are supplements regulated for what's on the label?

In the US, supplements are regulated as food, not drugs (DSHEA 1994), so the manufacturer, not the FDA, is responsible for label accuracy before sale. Independent testing repeatedly finds label-dose discrepancies and contamination in unverified products. The practical defense is third-party certification: look for Informed Sport, NSF Certified for Sport, or USP verification, which test the finished product against the label. Every comparison on this site notes certification status because an unverified gram is not the same as a verified gram, and the unverified one is not actually cheaper per effective dose.