Supplements: What's Actually Worth Taking
Organised by strength of evidence, not by marketing spend
The supplement industry is largely unregulated for efficacy claims, which means the evidence behind any given product varies enormously. This section stays focused on the training-specific angle — why lifters and athletes prioritise these particular options; see the Supplements guide for full dosing and evidence-strength detail on these and other options (vitamin D3/K2, magnesium, omega-3, creatine, and more).
Tier 1 — strong, consistent evidence
| Supplement | What it does | Notes |
|---|---|---|
| Creatine monohydrate | Why athletes care: tops up phosphocreatine (a molecule muscle uses to regenerate energy fastest, for short bursts of maximal effort), modestly improving high-intensity exercise capacity and supporting small additional gains in strength and muscle mass over time[58] | 3–5g/day; extensively studied, strong long-term safety record |
| Caffeine | Improves alertness and measurably improves endurance and high-intensity performance at moderate doses[59] | ~3–6mg/kg bodyweight, roughly 45–60 minutes pre-exercise |
| Whey/casein protein | Why athletes care: a convenient, complete protein source for hitting daily targets and post-workout intake without cooking or carrying food | Not superior to whole food protein gram-for-gram — purely a convenience tool |
| Vitamin D | Corrects a genuinely common deficiency, particularly in winter or low sun-exposure contexts | Worth testing blood levels rather than guessing dose |
Tier 2 — reasonable evidence, smaller or context-dependent effect
| Supplement | What it does | Notes |
|---|---|---|
| Beta-alanine | Buffers muscular acidity, may modestly help sustained high-intensity efforts (1–4 minutes) | Typically 3.2–6.4g/day; causes harmless tingling (paraesthesia) at higher single doses[60] |
| Omega-3 (fish oil) | Supports cardiovascular markers; relevant if oily fish intake is low | Most useful as a gap-filler, not a universal addition |
| Citrulline malate | May modestly improve training volume and reduce perceived fatigue | Effects are smaller and less consistent than creatine |
| Magnesium (incl. glycinate) | May improve sleep quality in people with poor sleep or low magnesium status | 200–400mg in the evening[61] |
| Zinc | Modestly shortens the duration of common cold symptoms when started within 24 hours of onset | Lozenges, ~75mg/day during a cold; chronic high-dose use can impair copper absorption[62] |
| L-theanine (with caffeine) | Combined with caffeine, may improve sustained attention and reduce caffeine-related jitteriness versus caffeine alone | ~200mg with ~100mg caffeine[63] |
Tier 3 — weak, inconsistent, or no credible evidence for the claims made
Fat burners / thermogenics — the only active ingredient that does anything is usually caffeine; the herbal blends around it rarely show independent benefit.
BCAAs (in isolation) — add nothing beyond what adequate total protein already supplies; skip if you're hitting your protein target.
Detox teas / cleanses — no real mechanism beyond a laxative or diuretic effect; any "weight loss" is water and gut content, not fat.
Testosterone boosters (over-the-counter) — almost none raise testosterone in men with normal baseline levels.
Alpha-GPC — marketed for strength and growth hormone output, but the supporting evidence is a single unpublished, unreplicated seven-person trial[64] — too thin to draw a conclusion either way.
Supplements supplement — they do not substitute
Every product in Tier 1 produces a measurable but modest effect on top of an already sound diet and training programme. None of them compensate for inadequate sleep, inconsistent training, or a calorie intake that does not match the goal. Spend the budget on food quality and consistency first.