The supplement industry is a $150+ billion global market. The science is clear: most supplements don't work for most people. A few are genuinely valuable.

Evidence-backed supplements:

• Vitamin D — if deficient (most people are)
• Omega-3 (EPA/DHA) — if low fish intake
• Magnesium — if insufficient dietary intake
• Creatine monohydrate — best-researched performance supplement. Increases strength and muscle
• Vitamin B12 — essential for vegans
• Iodine — if not using iodized salt
• Folate — critical during pregnancy

Largely unsupported by evidence: Most "fat burners," detox supplements, testosterone boosters, proprietary blends.

Key rule: Supplements should supplement a good diet — not replace it. Food provides thousands of bioactive compounds that cannot be replicated in a pill.

Reference:

Wikipedia: Dietary supplement

https://en.wikipedia.org/wiki/Dietary_supplement