Quick answer

For healthy adults without deficiencies, large reviews find multivitamins and single vitamins offer little or no benefit for preventing heart disease, cancer or death. Supplements help most when they correct a measured deficiency or meet a specific need. Personalised nutrition advice has been shown to change behaviour more than generic advice, so the value lies in targeting, not in taking more.

Key takeaways

  • A US Preventive Services Task Force review of 84 studies found little or no benefit of routine vitamins and minerals for preventing CVD, cancer or death.
  • Multivitamins showed only a small reduction in cancer incidence, with important limitations.
  • Some supplements carry risks: beta carotene increased lung cancer risk in high-risk groups.
  • In the Food4Me trial, personalised nutrition advice improved diet more than generic advice.
  • The smartest approach is to test, target real needs and re-measure, rather than take everything “just in case”.

Do multivitamins actually work?

It depends on what you expect them to do. For preventing chronic disease in well-nourished adults, the answer from the largest evidence reviews is: not much.

In 2022, an evidence review for the US Preventive Services Task Force analysed 84 studies involving nearly 740,000 people without known deficiencies. It concluded vitamin and mineral supplementation was associated with little or no benefit in preventing cancer, cardiovascular disease and death, with the exception of a small benefit for cancer incidence with multivitamin use, evidence it noted had important limitations 1.

Single nutrients fared no better. Vitamin D was not associated with lower all-cause mortality, cardiovascular disease or cancer outcomes, and vitamin E showed no benefit 1. In the large VITAL trial, 2,000 IU of vitamin D daily did not reduce invasive cancer or major cardiovascular events 2.

Can supplements be harmful?

Yes, which is why “more is better” is the wrong mindset. The same review found beta carotene increased the risk of lung cancer and cardiovascular death in people at high risk of lung cancer, and noted limited evidence linking some supplements with other serious harms, including hip fracture (vitamin A), haemorrhagic stroke (vitamin E) and kidney stones (vitamin C, calcium) 1.

So when do supplements make sense?

Supplements earn their place when there is a specific reason:

  • A measured deficiency, such as low ferritin or B12 confirmed by a blood test
  • A life stage need, such as folic acid before and during early pregnancy, or vitamin D for adults aged 75 and over 3
  • A dietary gap, such as B12 for vegans or omega-3s for people who eat no oily fish
  • A well-evidenced goal, such as creatine alongside strength training

In each case the dose, form and timing should fit the person, and results should be re-checked.

Does personalised nutrition work better?

The largest trial on this question is Food4Me, a randomised controlled trial across seven European countries. Participants received either standard healthy eating advice or personalised advice based on their diet, and in some groups also on their blood markers or genes.

Personalised advice led to larger and more appropriate improvements in diet than the conventional, one-size-fits-all approach. However, adding phenotypic (blood marker) or genetic information did not further enhance the effect in that trial 4. In other words, personalisation helped, but more data only helps if it is translated into clear, specific action.

How to choose supplements the evidence-based way

  1. Measure first. Blood tests show real gaps. DNA adds context on how you may process certain nutrients.
  2. Target, don’t stack. Add only what addresses a need or a goal with good evidence.
  3. Check safety. Stay within upper limits and review medicine interactions.
  4. Re-measure. Re-test to confirm a supplement is doing its job, then adjust or stop.

Frequently asked questions

Are personalised vitamins worth the money?

They are worth it when personalisation is based on real data, such as blood tests, diet and goals, and leads to fewer, better-targeted supplements. A quiz-based bundle that adds more products is unlikely to deliver more value than a well-chosen basic approach.

Should I stop taking my multivitamin?

Not necessarily. Multivitamins are generally low-risk at standard doses and may help people with limited diets. But do not rely on one to prevent disease, and check with your doctor if you take other supplements or medicines.

Which supplements have the strongest evidence?

Evidence is strongest for correcting diagnosed deficiencies (such as iron, B12 and vitamin D in at-risk groups), folic acid in pregnancy, and creatine for strength and muscle alongside training. Benefits for most other products in healthy people are small or uncertain.

Can I get everything I need from food?

Many people can meet most needs through a varied diet, but some groups, such as vegans, pregnant people, older adults and those with absorption issues, commonly need targeted supplementation.

Sources

  1. O'Connor EA, et al. Vitamin and mineral supplements for the primary prevention of cardiovascular disease and cancer: updated evidence report and systematic review for the US Preventive Services Task Force. JAMA. 2022;327(23):2334–2347. doi.org/10.1001/jama.2021.15650
  2. Manson JE, et al. Vitamin D supplements and prevention of cancer and cardiovascular disease (VITAL). N Engl J Med. 2019;380(1):33–44. doi.org/10.1056/NEJMoa1809944
  3. Demay MB, et al. Vitamin D for the prevention of disease: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2024;109(8):1907–1947. doi.org/10.1210/clinem/dgae290
  4. Celis-Morales C, et al. Effect of personalized nutrition on health-related behaviour change: evidence from the Food4Me European randomized controlled trial. Int J Epidemiol. 2017;46(2):578–588. doi.org/10.1093/ije/dyw186

Medical disclaimer: This article is for general information and education only and is not medical advice. It does not replace diagnosis or treatment by a qualified clinician. Talk to your doctor or pharmacist before starting supplements, especially if you are pregnant, take medicines or have a medical condition. Evidence reviewed as of 16 September 2026.