What supplements are genuinely worth taking for a man over 40 — the definitive list?

The supplements with the strongest evidence for men over 40, evaluated by intervention-grade evidence and real-world deficiency prevalence: (1) creatine monohydrate 3–5 g/day, Solid (1) for muscle strength and mass; (2) vitamin D3 2,000–4,000 IU/day with K2 90 mcg, Solid (1) for correcting prevalent deficiency, Promising (2) for cancer mortality; (3) magnesium glycinate 300–400 mg/day, Promising (2) for sleep, insulin sensitivity, cardiac rhythm; (4) omega-3 EPA+DHA 1–2 g/day, Promising (2) for anti-inflammatory and cardiovascular effects; (5) protein powder (if dietary intake is below 1.6 g/kg/day), Solid (1) for muscle mass maintenance (Phillips et al., J Physiol, 2012).

This list does not include NMN (Theoretical (4) in humans for longevity endpoints), testosterone boosters (mostly Unsupported (5) or Theoretical (4) for the marketed claims), CoQ10 (Early (3), meaningful only if on statins), resveratrol (Theoretical (4), human evidence inconsistent), or collagen supplements (Promising (2) for joint and skin specifically, not broadly). The honest answer to "what supplements should I take" excludes the majority of what the supplement industry sells to men in this demographic.

Honesty Scale: As rated per supplement above.

What to do: Start with the first four, in order. Add the fifth if dietary protein is inadequate. Review your supplement list against this framework and remove everything that does not meet at least a Promising (2) evidence grade for a specific health outcome you care about.

For the full picture, read The Supplementation Deep Dive