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There's more evidence the vitamin pills you think will do your body good aren't actually doing very much to keep you healthy.
When researchers examined existing data on four popular supplements — multivitamins, vitamin D, calcium and vitamin C — none showed "consistent benefit" for preventing cardiovascular disease, heart attack, stroke or premature death, according to a study published this week in the Journal of the American College of Cardiology. Taking those pills does no harm, but offers no apparent advantage either, said Dr. David Jenkins, the study's lead author and a professor of nutritional sciences and medicine at the University of Toronto.
"We were surprised to find so few positive effects of the most common supplements that people consume," Jenkins said in a statement. "In the absence of significant positive data... it's most beneficial to rely on a healthy diet to get your fill of vitamins and minerals."
Some supplements did stand out: Folic acid alone and B-vitamins with folic acid may reduce stroke, the analysis found. But niacin and antioxidants were associated with a higher risk of death.
The latest research comes after a Viewpoint article, published in JAMA in February, noted that more than half of Americans, or 52 percent, report using at least one dietary supplement, even though supplements aren’t a substitute for a healthy diet and provide little if any benefit for healthy adults.
The commentary aimed to separate facts from fiction, said Dr. JoAnn E. Manson, the lead author, chief of preventive medicine at Brigham and Women's Hospital and professor of medicine at Harvard Medical School.
“People are bombarded by the marketing for dietary supplements and they may not be fully aware of the lack of evidence for efficacy,” Manson told TODAY.
“[We want] to really encourage people to try to get these vitamins, minerals and other micronutrients from foods, from a healthy diet, because that’s where they’re best absorbed and you get an array of nutrients in biologically optimal ratios.”
While routine use of multivitamins and other supplements isn’t recommended for the general population, people in certain life stages or “high risk” groups can benefit from them, the JAMA article noted.
Here were some of the recommendations:
Focus on a healthy diet, rather than supplements
“A healthful, well-balanced diet that includes whole grains and whole foods will provide sufficient vitamins and minerals for the vast majority of the population,” Manson said.
“You have to be aware that vitamin supplements are not a substitute for fruits and vegetables. You’re talking about foods that have a very complex array of beneficial macronutrients and micronutrients, so it’s not the same.”
Avoid highly-processed products because processing will strip many foods of vitamins, minerals and fiber.
Multivitamins can fill in some gaps
Multivitamin and multimineral supplements are not recommended for generally healthy adults, the report noted. But if you’re concerned your diet is inadequate — perhaps because you don’t eat enough fruits and vegetables — and you’re not in a position to improve it, a multivitamin could fill in some of the gaps, Manson said.
“It is a reasonable form of insurance,” she noted.
People in certain life stages can benefit from supplements:
Pregnant women: Folic acid to prevent birth defects. “Synthetic folic acid actually is better absorbed than the dietary folate, so it’s important during pregnancy and during pre-conception planning to take folic acid and the prenatal vitamins,” Manson said.
Infants and children: For breastfed infants, vitamin D until weaning, and iron from age 4 to 6 months.
Middle-aged and older adults: Some may benefit from supplemental vitamin B12, vitamin D, and/or calcium.
People with certain medical conditions can also benefit:
Conditions that interfere with nutrient absorption or metabolism — including bariatric surgery, pernicious anemia, Crohn’s disease and osteoporosis — may require patients to take supplements.
"We were surprised to find so few positive effects of the most common supplements that people consume"
Beware of “mega” doses of supplements
It was once believed that taking high doses of nutrients such as beta carotene, folic acid, vitamin E or selenium would be beneficial, but clinical trials discovered they may have harmful effects instead, including increased mortality, cancer and hemorrhagic stroke, the paper noted.
“So we shouldn’t make the assumption that high-dose supplementation is free of risk,” Manson said.
“Now, with something like multivitamins, you’re talking about small to moderate doses, doses that are generally within the recommended dietary allowance, so the risks should be very minimal, if any.”
Research into vitamin D supplements in ongoing
There’s lots of buzz about vitamin D supplements, but do they really help?
Manson is the principal investigator of the ongoing VITAL study, the largest randomized clinical trial of vitamin D. Researchers are trying to find out whether taking daily supplements of vitamin D3 or omega-3 fatty acids reduces the risk for developing cancer, heart disease and stroke. The results are due later this year.
For now, Manson believes it’s best to follow the National Academy of Medicine’s guidelines and aim for 600-800 IUs of vitamin D a day, which should meet the requirements of most people.
If you’re not drinking fortified dairy products, not eating fatty fish or getting very limited sun exposure — all sources of vitamin D — supplements could help, she noted.
“I think it should be fine to take 1,000-2,000 IUs a day as a supplement, especially if you have osteoporosis, or bone health problems or you have concerns about your diet,” she said.
But many people are taking 10,000 IUs a day or higher and such high doses may have risks, including high blood calcium and high urine calcium, which may be linked to kidney stones, Manson noted.
There are no supplements to boost immunity
Supplements won’t ward off disease during a deadly flu season.
“It would be great to have a magic pill that could reduce the risk of developing a cold or flu… but at the present time, there is no magic bullet,” Manson said.
There is some evidence vitamin C may slightly shorten the duration of symptoms, she noted. But rather than popping vitamin C pills, it’s better to eat fruits and vegetables.
“And have some chicken soup,” Manson said.