The vitamin supplement market in the UK is huge – and growing. Annual sales of vitamin or mineral supplements were on track to reach £559 million by the end of 2025, according to market research firm Mintel. Yet the scientific evidence about the health benefits of these supplements is mixed.
Why do people take vitamin supplements? We absorb essential vitamins and minerals from foods including leafy green vegetables, fruit, whole grains, nuts, dairy and lean proteins. But increasing reliance on ultra-processed foods means that many people may not be getting these nutrients from what they eat – and vitamin supplements are intended to fill the gap.
What does the science say? The scientific picture is “complicated”, said Jasmin Fox-Skelly on BBC Future. Clinical trials have had “contradictory results”, and “suggest that whether you will benefit from taking vitamin supplements depends on who you are, as well as the exact micronutrient the supplement contains”. In addition, many single vitamin supplements “lack regulation, contain unlisted ingredients, and are not backed up by randomised controlled trials – the gold standard of medical research”.
The NHS advises that “in most cases”, taking supplements is “not necessary” because most people can get the essential nutrients they need from “eating a healthy, varied and balanced diet”. However, some supplements are recommended for specific groups: for instance, pregnant women should take vitamin B9 (folic acid) for the first 12 weeks of pregnancy, and vegans and vegetarians may benefit from taking a vitamin B12 supplement.
Are there any risks? Yes. “Mega-dosing” – taking large amounts of a particular vitamin – can be very harmful. For instance, excess vitamin A can cause severe headaches, blurred vision and problems with coordination, while mega-dosing vitamin C may result in stomach upset and diarrhoea.
Big-brand multivitamins, however, are designed to deliver only the recommended daily allowance of each vitamin and mineral, so taking them daily is not risky, said JoAnn Manson, a professor at the Harvard School of Public Health. For people worried that their diet isn’t healthy enough, “taking a multivitamin could be a form of insurance”.
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