Supplements vitamins and minerals — complete reference

The supplement industry is enormous, largely unregulated in most countries, and full of products that range from genuinely useful to inert to occasionally harmful. Evidence for supplementation is strongest when correcting a documented deficiency — vitamin D, iron, B12, magnesium, folate — and substantially weaker for most supplements marketed for enhancement or prevention in well-nourished people. The question to ask about any supplement is not whether it is natural but whether the evidence supports its use for your specific situation at a dose that is both effective and safe.