An estimated one-third of American adults and a quarter of children and adolescents take multivitamins, with US sales totaling $8 billion in 2020, according to the National Institutes’ Office of Dietary Supplements of health.
Some experts believe that a well-rounded, nutritious diet should be enough for many people. “I put my emphasis on whole foods,” says Donald D. Hensrud, 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 harder to absorb vitamins from food. Some also need supplements in addition to multivitamins.
“Some nutrients are very difficult to get from food, like vitamin D, since very little is found naturally in food,” says Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest (CSPI). “Many older people do not produce enough stomach acid to extract natural vitamin B-12 from milk, meat, or eggs. Vitamin B-12 deficiency can cause irreversible nerve damage and can mimic dementia, something you want to avoid.”
Scientists who study multivitamins say there is growing evidence that multivitamins may also provide additional health benefits, including slowing cognitive decline among older people. A recent three-year study of more than 2,200 participants over the age of 65 funded by the National Institute on Aging, for example, found that those who take a the daily multivitamin demonstrated significant cognitive improvement in skills that tend to decline with normal aging, including short-term memory and executive functions such as decision-making, compared with those given a placebo.
The unpublished results, which were presented at a scientific meeting in the fall, showed that people taking multivitamins showed only 1.2 years of mental decline, instead of three years. Put another way, they retained 1.8 years, almost 60 percent, of their mental acuity. The research was part of a larger trial looking at the effects of multivitamins on cancer. The cognition results are expected to be published soon.
The largest study, known as the COcoa and Multivitamin Supplement Outcomes Studyor COSMOS, started in 2014 to try to replicate the findings of an earlier trial, the Physicians Health Study II, which ran from 1997 to 2011. PHS II saw an 8 percent reduction in total cancers among people 50 and older who took daily multivitamins, but, unlike COSMOS, it showed no cognitive benefits. The COSMOS study, on the other hand, which lasted just three and a half years, found no decline in cancers.
But the researchers, the same ones in both studies, emphasize that differences in the design and duration of the two studies explain the apparently conflicting results.
“COSMOS was not long enough to discover the effects of cancer,” says Howard Sesso, an associate professor of medicine at Harvard Medical School and one of the researchers. “For cancer, it really takes longer to detect the impact of nutritional interventions. We are following up with the participants, sending out surveys to see if they are still taking multivitamins and to see if they have developed cancer.”
There were also significant differences between the two studies in the way they measured cognition. For example, the first baseline cognitive assessment in PHS II occurred a year or two after participants started taking the pills, meaning the researchers would have missed cognitive improvements that occurred in those first two years, he says. Sesso.
“COSMOS had a better study design,” he says. “The first baseline cognitive assessment was done before they started taking the multivitamin or placebo. Potential benefits were seen at follow-up evaluations at one, two, and three years.”
Regardless, experts say multivitamins are important for those who suffer from poor absorption, as a result of medications, gastric bypass surgery, or digestive disorders such as Crohn’s disease, ulcerative colitis, inflammatory bowel disease, and celiac disease.
Multivitamins can also provide needed nutrients during specific stages of life. Anyone considering becoming pregnant should take a multivitamin before and during pregnancy to ensure they get enough folic acid, which prevents fetal neural tube defects such as spina bifida. In contrast, postmenopausal women should avoid multivitamins that contain iron, since they no longer lose iron during menstruation.
Some people also require additional supplements such as B-12 and vitamin D. The latter, necessary for bone health, is often inadequate in those who avoid sun exposure, a wise practice to prevent skin cancer, and in those who they are confined indoors, like infants. household residents.
Manson has made several studies in vitamin D supplements that suggest taking additional vitamin D may lower the risk of developing Autoimmune diseases Y reduce cancer deathsalthough it does not prevent it. “Vitamin D can modify the biology of tumors so that they are less likely to metastasize,” 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 a little more is a good idea. (The Recommended Dietary Allowance, or RDA, is 600 international units, or IU, or 15 micrograms, but the amount varies among multivitamins.)
“During the pandemic, I recommend 1,000 to 2,000 IUs, although the jury is still out in terms of benefits during covid,” he says. “It’s very safe. For bone health and other chronic diseases, 600 to 800 is enough.”
Experts say it’s also smart to take vitamin B-12 supplements later in life. Most multivitamins contain 2.4 micrograms, the RDA for adults, but some people may need more, experts say.
“Approximately 15 percent of people over the age of 65 have an early vitamin B12 deficiency,” says Hensrud. He suggests that his patients in this age group take 500 to 1,000 micrograms a day. “Vitamin B-12 is poorly absorbed and has a high safety threshold,” meaning high doses don’t hurt, he says. “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 to get enough potassium by filling half your plate with fruits and vegetables, rather than reaching for a supplement,” says Liebman. “Whether you need a calcium supplement depends on how much you get from food.”
Premenopausal women and men up to age 70 need 1,000 milligrams of calcium daily, she says. “You can’t rely on a multi to get it because it wouldn’t fit on a single tablet and because you can get enough of food.”
Women need 2,600 milligrams of potassium a day, while men need 3,400 milligrams, she says. “Potassium can help lower blood pressure or keep it from rising with age,” says Liebman. In addition to fruits and vegetables, other sources of potassium They include dairy products, beans, and shellfish.
Most experts agree that taking a multivitamin can’t hurt and probably could help, and people don’t need to spend a lot of money on them.
“I think an ordinary multivitamin and mineral supplement is reasonable for many people,” says Liebman. “You don’t need the Cadillac of multivitamins. A Chevy is fine. Many own brands are usually perfectly adequate.”
What vitamins should your multivitamin have?
Vitamin A 700-1050mcg (2300-3500IU)
Vitamin D 20-25mcg (800-1000IU)
Vitamin E 13-35mg (20-80IU)
Thiamin (B-1) 1.1mg or more
Riboflavin (B-2) 1.1mg or more
folate Premenopausal women 660-680 mcg DFE (dietary folate equivalent) (400 mcg folic acid); all others 400-680 mcg DFE (235-400 mcg folic acid)
B12 vitamin 2.4mcg or more
Calcium Don’t trust a multivitamin
Iron Premenopausal women 18 mg; all others (no more than 8 mg)
Potassium Don’t trust a multivitamin
(Note: “Or more” does not mean a nutrient is safe at any dose, but levels in multivitamins are unlikely to be high enough to cause harm. This list does not apply to prenatal multivitamins for pregnant women.) Consult your doctor .)
