Do Supplements Work? An Evidence-Based Review

The supplement industry is worth over $150 billion globally. Most of it is built on marketing claims that outrun the science by a decade. Here's a tier list based on what the peer-reviewed research actually supports — not what the sponsored athletes tell you.

Tier 1: Strong evidence — these work

Creatine monohydrate

The single most studied sports supplement in history. Over 500 peer-reviewed studies. Creatine increases phosphocreatine stores in muscle, which improves high-intensity exercise performance, strength, and lean mass gains.

The effect size is meaningful: approximately 5–10% improvement in strength and 1–2kg additional lean mass over a training period compared to placebo. It also has emerging evidence for cognitive benefits.

Dose: 3–5g per day, every day. Loading phases (20g/day for a week) work faster but aren't necessary. Monohydrate is the form to buy — not HCL, not ethyl ester, not buffered. Monohydrate has the research behind it.

Reference: Kreider, R.B. et al. (2017). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. JISSN, 14, 18.

Caffeine

Caffeine is a performance enhancer. That's not controversial — it was banned by the World Anti-Doping Agency until 2004. It improves endurance performance, strength output, and training volume at doses of 3–6mg per kilogram of body weight, taken 30–60 minutes before training.

For an 80kg person, that's 240–480mg — roughly 2–4 cups of coffee. Habitual caffeine users may need the higher end due to tolerance.

Reference: Goldstein, E.R. et al. (2010). International society of sports nutrition position stand: caffeine and performance. JISSN, 7, 5.

Protein powder

Protein powder is food in a convenient form, not a magic supplement. If you can't hit your daily protein target through whole foods, protein powder closes the gap. Whey, casein, and plant-based blends all work — the protein source matters less than the total daily intake.

Tier 2: Moderate evidence — situationally useful

Vitamin D

If you're deficient (and many people are, especially in northern latitudes or indoor-heavy lifestyles), supplementation can improve muscle function, bone health, and immune response. If your levels are already adequate, supplementing more doesn't help. Get tested first. Dose if deficient: 1,000–4,000 IU/day.

Omega-3 fatty acids

Fish oil has anti-inflammatory properties and may support recovery. The evidence for direct performance benefits is limited, but the general health case (cardiovascular, cognitive) is reasonable. Dose: 1–3g combined EPA/DHA per day.

Tier 3: Weak or no evidence — save your money

BCAAs (Branched-Chain Amino Acids)

This is one of the most oversold supplements in the industry. If you're eating adequate protein, BCAAs provide zero additional benefit. They're literally a subset of the amino acids already in your protein. Taking BCAAs on top of adequate protein is like pouring a glass of water into a full bathtub.

The original BCAA research was done on fasted or low-protein populations. When total protein intake is sufficient (which it should be for anyone reading this), BCAAs add nothing.

Reference: Wolfe, R.R. (2017). Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? JISSN, 14, 30.

Fat burners / thermogenics

Most fat burners are caffeine with a marketing budget. The "proprietary blend" on the label is usually underdosed ingredients with no meaningful thermogenic effect. No supplement burns fat in the absence of a calorie deficit. The ones that do have measurable effects (ephedrine, DNP) are dangerous and banned in most countries for good reason.

Testosterone boosters

Tribulus, D-aspartic acid, fenugreek — none of them meaningfully increase testosterone in healthy males with normal levels. The studies that show "increases" are either measuring within normal fluctuation ranges or funded by the companies selling the product.

The bottom line