A daily multivitamin and mineral supplement may reduce cognitive decline in older people, according to a US study that is the first to demonstrate they may benefit ageing brain function.
The trial, involving more than 2,200 over-65s, suggests that daily supplements may slow cognitive decline by about 60%, or nearly two years, with the most substantial effects seen in older people with a history of cardiovascular disease.
But while experts in Alzheimer’s disease and dementia are encouraged by the findings, they caution that larger studies are needed to confirm the effect before recommending daily multivitamins to help protect older people from cognitive decline. Previous tests of dietary supplements have had no effect on the disease.
“We provide the first evidence in a long-term, randomised controlled trial of older women and men that daily use of a safe, readily accessible, and low-cost multivitamin-mineral can improve cognition,” the researchers wrote in Alzheimer’s and Dementia, the Journal of the Alzheimer’s Association. “This finding could have important public health implications for brain health and resilience against future cognitive decline.”
With populations ageing around the world, dementia has become one of the leading global health challenges, but there are no drugs that can cure any of the common types. In the UK, about 850,000 people live with dementia, most of which is Alzheimer’s disease or “vascular dementia”. People over 65, and those with diabetes, high blood pressure, high cholesterol and depression, are most at risk.
Researchers at Wake Forest University in North Carolina and Brigham and Women’s Hospital in Boston investigated whether a daily cocoa extract or multivitamins with minerals improved memory and other mental tasks in 2,262 people aged 65 and over. The researchers rated the participants’ “global cognition” before and during the three-year trial through tests involving word lists, number problems, verbal fluency and story recall.
Cocoa extract is rich in substances called flavanols and past research has suggested that they may have some benefit for brain function. But the latest trial found daily cocoa supplements made no difference to people’s cognitive performance. Daily multivitamin-mineral supplements, however, appeared to improve cognitive scores, in particular for those with cardiovascular disease, a known risk factor for dementia. The results suggest “either greater relative improvement or more protection from cardiovascular disease-related cognitive decline”, the authors wrote.
Prof Laura Baker, co-principal investigator on the Cosmos study at Wake Forest University, said it was too early to recommend daily multivitamins to prevent cognitive decline. “While these preliminary findings are promising, additional research is needed in a larger and more diverse group of people. Also, we still have work to do to better understand why the multivitamin might benefit cognition in older adults,” she said.
Prof Tara Spires-Jones, group leader at the UK Dementia Research Institute at Edinburgh University, said the study was well conducted, but noted that most people involved were highly educated white people.
“It will be important to confirm that the results hold up in the wider population,” she said. “It is also not clear from this study whether multivitamin use will prevent diseases affecting cognition like Alzheimer’s disease. Several dietary supplements have been tested as treatments for Alzheimer’s disease and so far none have been effective.”
Dr Maria Carrillo, chief scientific officer at the Alzheimer’s Association, said: “This is the first positive, large-scale, long-term study to show that multivitamin-mineral supplementation for older adults may slow cognitive ageing. While the Alzheimer’s Association is encouraged by these results, we are not ready to recommend widespread use of a multivitamin supplement to reduce risk of cognitive decline in older adults.
“Independent confirmatory studies are needed in larger, more diverse study populations,” she added. “It is critical that future treatments and preventions are effective in all populations.”
By: Ian Sample
Critics by Johns Hopkins Medicine
Half of all American adults—including 70 percent of those age 65 and older—take a multivitamin or another vitamin or mineral supplement regularly. The total price tag exceeds $12 billion per year—money that Johns Hopkins nutrition experts say might be better spent on nutrient-packed foods like fruit, vegetables, whole grains and low-fat dairy products.
The researchers concluded that multivitamins don’t reduce the risk for heart disease, cancer, cognitive decline (such as memory loss and slowed-down thinking) or an early death. They also noted that in prior studies, vitamin E and beta-carotene supplements appear to be harmful, especially at high doses.
“Pills are not a shortcut to better health and the prevention of chronic diseases,” says Larry Appel, M.D., director of the Johns Hopkins Welch Center for Prevention, Epidemiology and Clinical Research. “Other nutrition recommendations have much stronger evidence of benefits—eating a healthy diet, maintaining a healthy weight, and reducing the amount of saturated fat, trans fat, sodium and sugar you eat.”
The exception is supplemental folic acid for women of child-bearing potential, Appel says. “Folic acid prevents neural tube defects in babies when women take it before and during early pregnancy. That’s why multivitamins are recommended for young women.” The Centers for Disease Control and Prevention recommends that all women of reproductive age get 400 micrograms of folic acid daily. The amount of iron in a multivitamin may also be beneficial for women of child-bearing potential, Appel adds.
“I don’t recommend other supplements,” Appel says. “If you follow a healthy diet, you can get all of the vitamins and minerals you need from food.”
Whole grains: Grains such as whole wheat, brown rice and barley still have their fiber-rich outer shell, called the bran, and inner germ. It provides vitamins, minerals and good fats. Choosing whole grain side dishes, cereals, breads and more may lower the risk for heart disease, type 2 diabetes and cancer and improve digestion, too.
Saturated fat: A type of fat found in abundance in butter, whole milk, ice cream, full-fat cheese, fatty meats, poultry skin, and palm and coconut oils. Saturated fat raises levels of heart-threatening LDL cholesterol in your bloodstream. It can also interfere with your body’s ability to absorb blood sugar easily. Limiting saturated fat can help control your risk for heart disease.
Omega-3 fatty acids (oh-may-ga three fah-tee a-sids): Healthy polyunsaturated fats that the body uses to build brain-cell membranes. They’re considered essential fats because our body needs them but can’t make them on its own; we must take them in through food or supplements. A diet rich in omega-3s—found in fatty fish, like salmon, tuna and mackerel, as well as in walnuts, flaxseed and canola oil—and low in saturated fats may help protect against heart disease, stroke, cancer and inflammatory bowel disease.
The amounts of each vitamin type in multivitamin formulations are generally adapted to correlate with what is believed to result in optimal health effects in large population groups. However, these standard amounts may not correlate what is optimal in certain subpopulations, such as in children, pregnant women and people with certain medical conditions and medication.
The health benefit of vitamins generally follows a biphasic dose-response curve, taking the shape of a bell curve, with the area in the middle being the safe-intake range and the edges representing deficiency and toxicity. For example, the Food and Drug Administration recommends that adults on a 2,000 calorie diet get between 60 and 90 milligrams of vitamin C per day. This is the middle of the bell curve. The upper limit is 2,000 milligrams per day for adults, which is considered potentially dangerous.
In particular, pregnant women should generally consult their doctors before taking any multivitamins: for example, either an excess or deficiency of vitamin A can cause birth defects. Long-term use of beta-carotene, vitamin A, and vitamin E supplements may shorten life and increase the risk of lung cancer in people who smoke (especially those smoking more than 20 cigarettes per day), former smokers, people exposed to asbestos, and those who use alcohol.
Many common brand supplements in the United States contain levels above the DRI/RDA amounts for some vitamins or minerals. Severe vitamin and mineral deficiencies require medical treatment and can be very difficult to treat with common over-the-counter multivitamins. In such situations, special vitamin or mineral forms with much higher potencies are available, either as individual components or as specialized formulations.
Multivitamins in large quantities may pose a risk of an acute overdose due to the toxicity of some components, principally iron. However, in contrast to iron tablets, which can be lethal to children, toxicity from overdoses of multivitamins are very rare. There appears to be little risk to supplement users of experiencing acute side effects due to excessive intakes of micronutrients.There also are strict limits on the retinol content for vitamin A during pregnancies that are specifically addressed by prenatal formulas.
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