Iron
Vital if you're deficient — and genuinely harmful if you're not. Test before you ever supplement it.
A mineral central to carrying oxygen in the blood. Deficiency causes fatigue and poor performance and is common in menstruating women and endurance athletes.
Correcting a diagnosed deficiency restores energy and performance — a clear, strong benefit. But iron is one supplement you should not take blind: excess accumulates and can damage organs, and some people carry a genetic risk of overload.
- !Never supplement iron without a blood test — too much is dangerous.
- !Commonly causes constipation and stomach upset; keep well away from children.
Note:General information, not medical advice. Supplements interact with medications and conditions — check with your doctor before starting anything, especially if you're pregnant, nursing or managing a health condition.