\u201cFollowing years of rigorous research, I\u2019ve become increasingly cautious about the promises made for many brain supplements,\u201d she says. \u201cThey simply haven\u2019t held up in high-quality clinical trials. I don\u2019t believe there\u2019s convincing evidence that most slow down cognitive decline.\u201d<\/p>\n
Dr Manson\u2019s verdict comes as two new studies cast doubt on some of the most popular products. A major clinical trial published in eBioMedicine<\/a> found omega-3 fish-oil supplements failed to improve memory or slow Alzheimer\u2019s-related brain changes<\/a>.<\/p>\n Dr JoAnn Manson, professor of medicine at Harvard Medical School, has spent decades studying the effects of dietary supplements on health and ageing – Rose Lincoln<\/p>\n A separate study<\/a> found glucosamine \u2013 the popular joint-health supplement once also thought to help protect against dementia \u2013 may accelerate the disease in people with Alzheimer\u2019s or mild cognitive impairment.<\/p>\n \u201cWe know deficiencies of certain nutrients are linked to cognitive decline and dementia,\u201d says Dr Manson. \u201cThe question is whether taking supplements is beneficial if you\u2019re not deficient in the first place.\u201d<\/p>\n Here are the supplements to take and avoid.<\/p>\n MultivitaminsThe best choice<\/p>\n If there\u2019s one supplement Dr Manson recommends for brain health, it\u2019s a daily multivitamin.<\/p>\n \u201cThere\u2019s stronger evidence for taking a comprehensive multivitamin and multimineral than almost any other dietary supplement tested for brain health,\u201d she says. \u201cI think of it as nutritional insurance.\u201d<\/p>\n In the landmark Cosmos study<\/a> (Cocoa Supplement and Multivitamin Outcomes Study) of 5,000 people aged over 60, Dr Manson and her team found a daily multivitamin slowed the rate of cognitive decline by as much as 60 per cent over three years.<\/p>\n \u201cMany older adults are deficient in at least one micronutrient out of the 20 or more vitamins and minerals in a multivitamin,\u201d she explains. \u201cA comprehensive supplement covers all those possible gaps. No single nutrient is likely to be the magic bullet for brain health so, if you take only vitamin C or vitamin B12 and don\u2019t have a deficiency in them, you\u2019re unlikely to see any cognitive benefit.\u201d<\/p>\n A multivitamin is also the safest way to supplement your diet<\/a>. \u201cOnce you start taking high doses of a single nutrient, the potential for harm increases,\u201d says Manson. \u201cMegadosing can interfere with absorption of other micronutrients and some supplements have been linked to liver damage or increased risk of certain diseases.\u201d<\/p>\n The bottom line: If you\u2019re older than 60, it\u2019s worth considering a daily multivitamin, says Manson. \u201cWe already know it can lead to a small reduction in cancer risk and all-cause mortality, and now there\u2019s increasing evidence multivitamins can slow cognitive ageing and possibly slow cellular ageing.\u201d<\/p>\n Dr Manson recommends taking a standard multivitamin containing the recommended daily intake of at least 20 vitamins and minerals.<\/p>\n Fish oilThe jury is out<\/p>\n We all know oily fish is good for the brain, but is it worth popping a daily fish-oil supplement too?<\/p>\n Oily fish, such as salmon, sardines and mackerel, are rich in the omega-3 fatty acids DHA and EPA, which are vital for brain function. Higher blood levels of omega-3s in midlife are linked to better cognitive health.<\/p>\n Yet a new trial<\/a> from Keck School of Medicine found that while high-dose DHA supplementation reached the brain, it failed to improve brain health in older people at risk of Alzheimer\u2019s.<\/p>\n The findings don\u2019t surprise Dr Manson. \u201cMarine omega-3s have been studied extensively for cognitive health but, overall, the evidence has been mixed,\u201d she says. \u201cWe looked at this in the Vital trial<\/a> (the Vitamin D and Omega-3 trial) \u2013 a five-year study of more than 25,000 people \u2013 and found no clear benefit from taking one gram a day of EPA and DHA for slowing cognitive decline.\u201d<\/p>\n Fish oil supplements contain omega-3 fatty acids DHA and EPA, but recent research has found little evidence they can slow cognitive decline – Evgeniia Siiankovskaia<\/p>\n That doesn\u2019t mean omega-3s aren\u2019t important. \u201cThey\u2019re an essential nutrient and there\u2019s good evidence supplements can benefit heart health, particularly in people who eat very little fish,\u201d says Manson. \u201cHeart disease and stroke are closely related to cognitive decline so what\u2019s good for the heart is usually good for the brain. But the benefits are not guaranteed.\u201d<\/p>\n Scientists believe omega-3s may be more effective for brain health when consumed as part of a Mediterranean-style diet which is naturally rich in omega-3s from fish, nuts and dark green leafy vegetables.<\/p>\n The bottom line: Focus on getting omega-3s from your diet rather than relying on a supplement. \u201cI recommend eating two or more servings of oily fish a week as part of a Mediterranean-style diet rich in vegetables, fruit, whole grains, nuts and healthy fats,\u201d says Manson. \u201cDietary supplements should never be a substitute for a healthy diet.\u201d If you don\u2019t eat fish, or have very little, she recommends a daily supplement containing 1g of marine omega-3s, ideally with a ratio close to 50:50 of DHA.<\/p>\n Vitamin B12Vital if you\u2019re deficient<\/p>\n If you\u2019re struggling with brain fog or poor memory<\/a>, one of the first things to check is your vitamin B12 level<\/a>.<\/p>\n \u201cVitamin B12 deficiency is one of the few, potentially reversible causes of cognitive decline,\u201d says Manson. \u201cTreating a deficiency with supplements can improve symptoms.\u201d<\/p>\n Our body needs vitamin B12 to keep nerve cells healthy and make neurotransmitters, the chemical messengers that allow brain cells to communicate. Chronic deficiency can lead to memory problems, depression and, eventually, brain atrophy.<\/p>\n B12 is found only in animal products or fortified foods, meaning vegetarians and vegans are at greater risk of deficiency. Our ability to absorb it also declines as we get older. According to NHS figures, around one in 20 people aged 65 to 74 and one in 10 people aged 75 and older have B12 or folate deficiency.<\/p>\n Yet, despite the link between low levels of B12 and cognitive decline, clinical studies, including those involving Alzheimer\u2019s patients, haven\u2019t found taking B12 supplements improves cognition in people whose levels are already adequate.<\/p>\n \u201cSome people genuinely need extra B12,\u201d says Manson. \u201cThat includes those with pernicious anaemia or who are taking medications such as metformin that reduce absorption. Otherwise, I wouldn\u2019t routinely recommend high-dose vitamin B12 supplements.\u201d<\/p>\n The bottom line: Don\u2019t take B12 in the hope it will sharpen your memory. If you\u2019re suffering symptoms or are at risk of deficiency, ask your GP about a blood test. \u201cFor most healthy people, a multivitamin provides sufficient B12,\u201d says Manson. \u201cA healthy diet including meat, fish, eggs, dairy and fortified foods should cover your daily needs. If you\u2019re vegan or eat a largely plant-based diet, consider a B12 supplement, and discuss the dose with your GP.\u201d<\/p>\n Vitamin DOnly if you\u2019ve got low levels<\/p>\n One in six people in the UK have low levels of vitamin D \u2013 often called the sunshine vitamin because our bodies make it when sunlight hits the skin.<\/p>\n Not just important for healthy bones, vitamin D also protects our brain health. Low levels have been linked to poor memory and thinking skills and studies suggest deficiency may increase the risk of dementia.<\/p>\n A large trial of more than 1,600 people, in Neurology<\/a>, found those with moderate vitamin D deficiency were more than 50 per cent more likely to develop Alzheimer\u2019s or dementia. For those with severe deficiency, the risk was 125 per cent higher.<\/p>\n However, that doesn\u2019t mean everyone benefits from taking a high-dose supplement. In the five-year VITAL trial of more than 25,000 people, Dr Manson and colleagues found taking 2,000 IU of vitamin D3 a day failed to significantly slow cognitive decline in adults whose vitamin D levels were already adequate.<\/p>\n \u201cWe saw benefits only in those who started out with lower levels,\u201d she says. \u201cThat tells us the issue is correcting a deficiency rather thanbenefits from giving everyone extra vitamin D.\u201d<\/p>\n The bottom line: The Government recommends UK adults take a daily 10mcg (400IU) vitamin D supplement during autumn and winter. \u201cPeople at high risk of deficiency, such as those with osteoporosis, fat malabsorption or who get little sunlight exposure, may benefit from 1000-2000 IU a day,\u201d says Manson. \u201cFor everyone else, the evidence for brain health benefits is much less convincing.\u201d<\/p>\n GlucosamineBe cautious<\/p>\n Recent research has raised fresh questions about glucosamine, one of the most popular supplements for joint pain.<\/p>\n A large study<\/a> from the University of Florida found people with mild cognitive impairment who took glucosamine were 28 per cent more likely to develop Alzheimer\u2019s disease. Among those who already had Alzheimer\u2019s, glucosamine users were 27 per cent more likely to die during the follow-up period.<\/p>\n While the exact reason isn\u2019t yet clear, researchers believe glucosamine, an amino sugar, may disrupt glucose metabolism in the brain.<\/p>\n \u201cWhile it\u2019s important not to overinterpret a single study, the research raises legitimate concerns,\u201d says Manson. \u201cGiven there\u2019s never been consistently strong evidence that glucosamine improves joint problems, I wouldn\u2019t recommend taking it routinely, particularly in people with existing cognitive impairment.\u201d<\/p>\n The bottom line: If you\u2019re taking glucosamine, discuss it with your doctor, advises Dr Manson. \u201cIf you\u2019re not seeing any benefit for your joints, consider whether you need to continue it,\u201d she says. \u201cIf you have cognitive impairment, it\u2019s probably best to forgo it, unless under the supervision of your doctor.\u201d<\/p>\n Don\u2019t waste your money on these<\/p>\n Many popular brain supplements simply haven\u2019t been tested well enough to justify recommending them, says Dr Manson.<\/p>\n Ginkgo biloba<\/p>\n![\"Dr](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/08\/887a0132-dc29-4793-9421-7de9818b482f.jpeg\"\/)
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