An estimated one-third of American adults and a quarter of children and teens take multivitamins, with total US sales reaching $8 billion in 2020, according to the National Institutes of Health’s Office of Dietary Supplements.
Some experts believe that a nutritious and comprehensive diet should suffice for many people. Donald D. says: “My focus is on whole foods,” Hensrud, MD, associate professor of nutrition and preventive medicine at the Mayo Clinic School of Medicine. “I focus on helping my patients eat a healthy diet.”
But other experts say it’s more complicated, because people often need more vitamins at certain stages of life or have health conditions that make it difficult to absorb vitamins from food. Some also need supplements in addition to a multivitamin.
“Some nutrients are very difficult to get from food, like vitamin D, because so little occurs naturally in foods,” says Bonnie Lipman, MD, director of nutrition at the Center for Science in the Public Interest (CSPI). Many older adults do not produce enough stomach acid to extract natural vitamin B12 from milk, meat, or eggs. Vitamin B12 deficiency can cause irreversible neurological damage and can mimic dementia — something you want to avoid.”
Scientists who study multivitamins say there is growing evidence that multivitamins can also impart additional health benefits, including delaying cognitive decline among older adults. A recent three-year study of more than 2,200 participants 65 and older funded by the National Institute on Aging, for example, found that those who take Daily multivitamins showed significant cognitive improvement In abilities that tend to deteriorate with normal aging, including short-term memory and executive functions such as decision-making, when compared to those who received a placebo.
The unpublished results, which were presented at a science meeting in the fall, showed that those taking the vitamins showed only 1.2 years of mental decline, instead of three. In other words, they maintained 1.8 years — nearly 60 percent — of their sharpness of mind. The research was part of a larger trial that looked at the effects of multivitamins on cancer. The realization results are expected to be published soon.
The largest study, known as COcoa supplement and multivitamin results studyor COSMOS, in 2014 to try to replicate the results of a previous experiment, and Physicians’ Health Study II, which lasted from 1997 to 2011. PHS II saw an 8 percent reduction in total cancers among those 50 and older who took a daily multivitamin, but — unlike COSMOS — showed no cognitive benefits. On the other hand, the COSMOS study, which only lasted 3½ years, found no reduction in cancers.
But the researchers – the same in both studies – stress that differences in the design and length of the two studies explain the seemingly contradictory results.
“COSMOS hasn’t been long enough to elicit cancer effects,” says Howard Sisso, MD, associate professor of medicine at Harvard Medical School and one of the researchers. “For cancer, you really need more time to discover the effect of dietary interventions. We follow up with participants, send out questionnaires to see if they are still taking multivitamins and see if they have developed cancer.”
There were also significant differences between the two studies in how cognition was measured. For example, the first assessment of baseline cognition in PHS II occurred one to two years after participants started taking the pills, meaning that researchers missed any cognitive improvements that occurred in the first two years, Siso says.
“COSMOS had a better study design,” he says. “The first baseline assessment of cognition was done before they started taking a multivitamin or a placebo. Potential benefits were seen in follow-up assessments at one, two and three years.”
Regardless, experts say multivitamins are important for those with poor absorption as a result of medications, gastric bypass surgery, or gastrointestinal disorders such as Crohn’s disease, ulcerative colitis, inflammatory bowel disease, and celiac disease.
A multivitamin can also provide nutrients that are necessary during certain stages of life. Anyone considering pregnancy should take a multivitamin before and during pregnancy to make sure they get enough folic acid, which prevents fetal neural tube defects such as spina bifida. By contrast, postmenopausal women should avoid iron-containing multivitamins, because they no longer lose iron during menstruation.
Some people also need additional supplements such as vitamin B12 and vitamin D, the latter, which is essential for bone health, is often insufficient for those who avoid exposure to sunlight—a prudent practice to prevent skin cancer—and indoors, such as nursing home residents.
Manson conducted many of studies Taking a vitamin D supplement indicating that you take extra vitamin D can reduce your risk autoimmune diseases And the Reducing deaths from cancer, although not prevented. “Vitamin D may modify the biology of tumors so that they are less likely to spread,” she says.
It is also studying the effect of vitamin D on coronavirus symptoms – specifically whether it can reduce upper respiratory infections – but there are no results yet. However, she thinks taking more of her is a good idea. (The recommended daily allowance, or RDA, is 600 international units, or IUs, or 15 micrograms, but the amount varies among multivitamins.)
“During the pandemic I recommend 1,000 to 2,000 IU, although the jury is still out on benefits during a pandemic,” she says. “It is very safe. For bone health and other chronic diseases, 600 to 800 is sufficient.”
Experts say it’s also smart to take a vitamin B12 supplement later in life. Experts say most multivitamins contain 2.4 mcg, which is the RDA for adults, but some people may need more.
“Approximately 15 percent of people over the age of 65 have an early vitamin B12 deficiency,” Hensrud says. He suggests that his patients in this age group take 500 to 1,000 mcg daily. “Vitamin B12 is not well absorbed and has a significant safety profile,” he says, which means higher doses won’t hurt. “It’s probably the safest vitamin out there.”
CSPI warns consumers not to rely on multivitamins to get enough calcium and potassium. “It’s better for you to get enough potassium by filling half your plate with fruits and vegetables, rather than looking for a supplement,” Lipman says. “Whether you need a calcium supplement depends on how much you get from foods.”
She says perimenopause women and men up to age 70 need 1,000 milligrams of calcium per day. “You can’t count on a multi device to get it because it won’t fit in one tablet, and because you might get enough of it food. “
She says women need 2,600 milligrams of potassium per day, while men need 3,400 milligrams. “Potassium can help lower blood pressure or help keep it from rising with age,” Lipman says. In addition to fruits and vegetables, Other potassium sources It includes dairy products, beans, and seafood.
Most experts agree that taking a multivitamin can’t hurt and possibly help, and people don’t need to spend a lot of money on them.
“I think a regular multivitamin and mineral supplement makes sense for a lot of people,” Lipman says. “You don’t need a Cadillac multivitamin. Chevy is fine. Usually a lot of store brands are just fine.”
What vitamins should be in your multivitamin
Vitamin A 700-1,050 mcg (2300-3500 IU)
Vitamin D 20-25 mcg (800-1000 IU)
Vitamin E 13-35 mg (20-80 IU)
Thiamine (B-1) 1.1 mg or more
Riboflavin (B-2) 1.1 mg or more
Folic acid Premenopausal women 660-680 mcg DFE (dietary folate equivalent) (400 mcg folic acid); Anyone else 400-680 mcg DFE (235-400 mcg folic acid)
Vitamin B12 2.4 mcg or more
Calcium Don’t rely on vitamins
iron Premenopausal women 18 mg. anyone else (no more than 8 mg)
potassium Don’t rely on vitamins
(Note: “or more” does not mean a nutrient is safe at any dose, but it is unlikely that levels in a multivitamin are high enough to cause harm. This list does not apply to prenatal multivitamins for pregnant women. See your doctor.)