Popping a multivitamin each morning has long been seen as a good health insurance policy - a handy way to fill in the gaps in less-than-perfect modern diets.
Half of UK adults take a multivitamin regularly, data from The Grocer shows. However, over the past decade, research has suggested that taking them might not be as beneficial as we think.
Tim Spector, a professor of genetic epidemiology at King's College London, says: 'When you look at high-quality trials, multivitamins simply don't work for most people. They add little or nothing beyond what a nutritious, diverse diet provides.'
Vitamins from food sources are also absorbed more easily by the body, plus you get the benefits of other nutrients in foods, such as fibre.
Some experts have also warned that people who take different supplements at the same time could end up overdosing on particular nutrients without realising, which can be dangerous. For example, excess iron can cause heart problems and excess vitamin A can lead to liver damage.
'The value of multivitamins is surprisingly uncertain,' says Aidan Goggins, a pharmacist and independent adviser to the supplement industry.
'A recent review of 19 studies, including 91,000 people, concluded that multivitamins don't reduce the risk of dying early in the general population [the journal Ageing Research Reviews reported in January].'
In fact, when, in 2024, researchers at the National Cancer Institute in the US analysed data from studies of adults with no major long-term diseases, they found that rather than living longer, people who took multi-vitamins daily were marginally more likely than non-users to die over the following two decades.
But that doesn't mean they have no value. While evidence for actual benefits of multivitamins is weak, there are some subgroups who have low intakes of some vitamins and minerals, says Philip Calder, a professor of nutritional immunology at Southampton University. 'And these are the people who might still benefit from them.'
So who needs to consider taking one? If you fall into any of the following categories, it's worth asking your doctor for a blood test to confirm any deficiencies, 'as without knowing what you are genuinely low in, taking a multi-vitamin becomes like roulette', says Aidan Goggins.
OVER-60s
As we age, nutrient absorption in the gut declines due to a combination of factors, including reduced stomach acid (which makes digestion less efficient), medication side-effects and a generally lower appetite. Slower movement of food through the gut with age also means it sits too long in the small intestine, where it can ferment and cause bacteria overgrowth. These bacteria can consume nutrients, such as calcium and vitamins B12 or D, before the body can absorb them.
'Older people are a group which seems to benefit most from multivitamins', says JoAnn Manson, a professor of medicine at Harvard Medical School.
Specifically, research has linked taking a multivitamin to a reduction in cognitive decline. In a 2024 trial, published in the American Journal of Clinical Nutrition, 21,000 people were monitored after either taking a multivitamin (Centrum Advance 50+ in the UK) or a placebo, for about three years. Results showed that those who took the multivitamin had significantly higher brain function and memory test scores, leading researchers to conclude that taking a multivitamin could slow brain decline by two years.
It is thought they work on several levels. For example, vitamins A, C and E protect brain cells from age-related damage, while B vitamins boost cell function and lower levels of homocysteine in the blood, a protein linked to dementia.
LOOK FOR:
Products which contain 100 per cent of the recommended daily amounts of vitamins B12 and D, magnesium and calcium (common deficiencies in this age group).
WATCH OUT FOR:
Too much iron in supplements. Choose a product with little or none in 'as it can often cause constipation or other digestive issues in older men and post-menopausal women', says Aidan Goggins.
GUT CONDITIONS
The small intestine is lined with villi - tiny, finger-like projections which increase surface area for nutrient absorption. But inflammation caused by some gut conditions, such as inflammatory bowel conditions (Crohn's disease and ulcerative colitis) and coeliac disease, can destroy them.
This reduces the body's ability to absorb nutrients from food, in particular, vitamins A, B9, B12, D, as well as calcium and iron, leading to deficiencies. People with these conditions should have regular blood tests to check their nutrient levels. Research in patients with inflammatory bowel conditions has shown that deficiencies can be reversed by taking a multivitamin. However, the problem within the gut lining can also affect how the body absorbs supplements. So opt for one which bypasses the gut, such as oral sprays (absorbed into the bloodstream via the mucous membranes in your mouth) or transdermal patches (nutrients pass through the skin barrier into the blood).
LOOK FOR:
Check with your doctor first, but a product which contains vitamins A, B9, B12 and D and calcium is useful. Skin patch and spray supplements may be more effective than pills.
WATCH OUT FOR:
Don't be tempted to self-prescribe iron. You should only take it if blood tests show low ferritin (iron stores) and blood levels, as it can worsen gut symptoms during active inflammation, says Aidan Goggins.
VEGAN/VEGETARIAN
'Some nutrients such as vitamin B12 are only found in animal-based foods so vegans and vegetarians can become deficient in them,' says Professor Philip Calder. Research suggests that vegans may also benefit from supplements of vitamin D, iodine, selenium, calcium and iron.
A 2025 study in the European Journal of Nutrition found that taking a daily multivitamin for four months significantly improved vitamin B12, selenium and iodine levels in adult vegans.
LOOK FOR:
A multivitamin which contains B12, selenium, calcium and iodine. The British Dietetic Association advises that if you are relying on a multivitamin for vitamin B12, it should contain at least 10mcg for adults daily.
WATCH OUT FOR:
'Too much seaweed - it's a common "natural" way for vegans to top up on iodine, but its levels vary wildly and can veer too high,' warns Aidan Goggins.
'Excess iodine can disrupt thyroid function and lead to tiredness and weight gain.' A multivitamin should not contain more than 0.5mg iodine.
UNDER-FIVES/PICKY EATERS
In the UK, the NHS recommends that all children aged six months to five years take a daily supplement containing vitamins A, C and D, 'because these nutrients support rapid growth, strong immunity and healthy development', says Clare Thornton-Wood, a dietitian in Guildford.
Poor diets that leave millions lacking eight key vitamins and minerals
'Vitamin A aids vision and immune function, vitamin C helps iron absorption and tissue repair, and vitamin D is essential for building strong bones and teeth,' she says.
'While a balanced diet often provides most necessary nutrients, taking these vitamins is recommended to ensure optimal growth and development.'
Older children who are picky eaters or those with restricted diets (for example, vegan or due to illness or allergies) may be low in key nutrients - 'iron, vitamin D, vitamin B12 and iodine being most common,' says Clare Thornton-Wood - and may benefit from a broader multivitamin. This should be discussed with a doctor or dietitian first.
LOOK FOR:
'A chewable multi-vitamin which contains iron and B vitamins plus vitamin D,' says Clare Thornton-Wood.
WATCH OUT FOR:
If a daily multivitamin contains vitamin D, children shouldn't take a separate D supplement on top. (Children aged one to ten should have no more than 50mcg a day.)
NUTRITION RISKS IN YOUR MEDICINES
Many commonly prescribed drugs can interfere with the body's ability to absorb nutrients. 'The long-term impact of certain medications on nutrient levels is rarely discussed,' says Gurdeep Nanra, a pharmacist in London. 'But over time, hidden deficiencies may affect overall health.'
Talk to your GP about a blood test to check for deficiencies and a suitable multivitamin if you take regular medication, including:
- PROTON PUMP INHIBITORS: Drugs such as omeprazole reduce stomach acid to treat heartburn, but can make it harder for your body to absorb nutrients such as iron, calcium, magnesium and vitamins B12 and C.
- GLP-1 INJECTIONS: Weight loss jabs can lead to deficiencies in zinc and vitamins B12 and D by interfering with nutrient absorption in the gut because they slow digestion and reduce appetite.
- METFORMIN: Taken to cut blood sugar; it can deplete levels of vitamin B12, folate and CoQ10.
- HORMONE MEDICATION: Research has linked the Pill and HRT to lower levels of vitamins B6,B9,B12,C and E; as well as magnesium and zinc. This could be because synthetic hormones alter gut microbiome so fewer nutrients absorbed;and because oestrogen medications trigger kidneys excrete more magnesium,zinc&selenium urine.
One trial found women taking a multivitamin alongside the Pill experienced less nausea,mood swings&breast tenderness.