Vitamin D: who actually needs a supplement?

Vitamin D gets treated like a cure-all — for energy, mood, immunity, weight. The evidence is more modest. For most healthy people, a supplement isn’t the magic fix it’s sold as; for specific groups, it genuinely matters.

What the evidence actually shows

In healthy adults without symptoms, expert reviews (including the USPSTF) found that routine vitamin D supplements don’t meaningfully reduce fractures, mortality, mood problems or infections. So blanket high-dose supplementing isn’t supported.

Who should consider testing or a supplement

• little sun exposure or mostly covered skin;
• older adults, and people with darker skin;
• conditions that reduce absorption (gut disease, some medications);
• pregnancy or breastfeeding (ask your doctor).

For these groups a common dose is 400–1000 IU/day, ideally guided by a test.

Getting enough sensibly

Sunlight and food (fatty fish, eggs, fortified dairy or plant milks) contribute. If you think you’re at risk, ask your doctor to check your level rather than guessing — more isn’t better, and very high doses can harm.

Frequently asked questions

Should everyone take vitamin D?

No. In healthy, low-risk adults, routine supplements haven’t been shown to reduce fractures, mortality, mood issues or infections. It’s most useful for specific at-risk groups.

Who is at risk of low vitamin D?

People with little sun exposure, darker skin, older adults, those with malabsorption conditions, and during pregnancy or breastfeeding. These groups should ask their doctor about testing.

How much vitamin D should I take?

For at-risk adults, a common range is 400–1000 IU/day, ideally guided by a blood test. Very high doses can be harmful, so don’t self-prescribe megadoses.

This article is educational and not medical advice. Test and supplement under your doctor’s guidance, especially in pregnancy or with medical conditions.