- Researchers say multivitamins and mineral supplements don’t improve a person’s overall health unless they have known deficiencies of these substances.
- They say the “placebo effect” may result in people saying they feel better after taking daily vitamins.
- Experts say certain vitamins may have some benefits, but you’re better off getting your nutrition through healthy foods.
People in the United States reportedly spend more than $30 billion per year on vitamins and supplements.
About 3 in 4 Americans takes a dietary supplement every day.
However, there’s scant evidence that multivitamins or mineral supplements have any positive impact on health, except for people with known vitamin or mineral deficiencies.
And while taking daily vitamins may make you feel better, in most cases that’s likely just the placebo effect at work, a new study suggests.
The research, published in the journal BMJ Open, compared self-reported and clinically measurable health outcomes among a group of more than 21,000 multivitamin users and nonusers in the United States.
Of these, 4,933 said they regularly took multivitamins or mineral supplements while 16,670 said they did not.
The study, which drew data from the
But supplement users scored no higher than nonusers when their psychological, physical, and functional health was assessed.
The NHIS includes questions on subjective self-assessments of health, including the need for help with routine daily activities as well as personal history of long-term conditions such as high blood pressure, asthma, diabetes, and arthritis.
It also asks about the presence of common health conditions in the preceding 12 months, including infections, memory loss, neurological and musculoskeletal problems, and individuals’ degree of psychological distress.
“Multivitamin users self-reported better overall health despite no apparent differences in clinically measurable health outcomes,” the study concluded.
“These results suggest that widespread use of multivitamins in adults may be a result of individuals’ positive expectation that multivitamin use leads to better health outcomes, or a self-selection bias in which multivitamin users intrinsically harbor more positive views regarding their health,” researchers wrote.
The researchers, led by medical student Manish Paranjpe of Harvard Medical School in Massachusetts, speculated that users’ positive associations between vitamins and better health may be tied to the fact that multivitamins are typically “sold to the so-called ‘worried-well.’”
The study found that, compared to nonusers, people who regularly took vitamins were older and had higher household incomes.
They were also more likely to be women, college graduates, married, and to have health insurance.
Many of those factors are associated with better health and quality of life.
“People who take multivitamins may just naturally be more positive,” Paranjpe told Healthline.
The observational study relied on self-reported vitamin use and health assessments. Researchers also didn’t look at how health assessments may have changed before and after beginning to take vitamins regularly.
Paranjpe said that there’s some evidence supporting vitamin and mineral supplementation in certain circumstances, such as folic acid for people during pregnancy and vitamin D supplements for older adults, particularly those who get limited sun exposure.
A 2012 study published as part of the Physicians Health Study by the American College of Cardiology also concluded that “daily intake of a multivitamin results in a small, but statistically significant decrease [in all forms of cancer].”
However, Paranjpe said, “for the general population, without a specific nutritional deficiency, there’s no evidence that supplements are required.”
“People are spending a lot of money on supplements that they could be spending on proven interventions like gym memberships or eating a healthier diet,” said Paranjpe.
“There is a lot of accumulated evidence that suggests multivitamins have no significant health benefits for the general healthy population. And this evidence has existed for a long time,” said Aaron Emmel, PharmD, founder and director of PharmacyTechScholar.com.
“Despite this, it is still common belief that taking a multivitamin daily is a healthy thing to do,” he told Healthline.
Evie Whitehead, a nutritional therapist, told Healthline that multivitamins contain “relatively small amounts of many nutrients which are unable to correct an underlying deficiency if there is one. However, a ‘capture-all’ multivitamin can provide a gentle support to someone in need of varying nutrients they may be short on.”
“My approach always looks at food first to cover nutrient needs, as I often see clients who look for a magic pill in the form of a supplement rather than change what is at the end of their fork,” she said.
Whitehead, however, doesn’t rule out supplements if the placebo effect helps users believe they’re taking positive steps for their health.
On the other hand, you don’t need to pay for vitamins to get a placebo effect, said Jason Reed, PharmD, creator of the website BestRxforSavings.com.
“As long as deficiencies are not a problem, thinking that your diet is providing you what you need could be just as powerful as thinking a multivitamin will make you feel better,” he told Healthline.
Emmel said that vitamins are no substitute for a healthy, balanced diet.
“If you look at the body of evidence regarding this, there is clearly a link between dietary habits and health outcomes such as diabetes, cardiovascular disease, and cancer,” he said.
“I think one of the key takeaways from the studies is that diet matters for good health, and vitamins matter only in special circumstances or when there is a known deficiency,” Emmel added.
Andrea Wong, PhD, senior vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, a trade group for the supplement industry, told Healthline that the study “in no way discount the multivitamin’s many benefits in combatting insufficient nutrient levels and promoting optimum health, nor does it provide basis for consumers to reconsider their decision to take a multivitamin or to take one in the future.”
Wong pointed to government reports showing that many Americans fall short of attaining their nutritional needs, including deficiencies in vitamins A, C, D, E, and K, calcium, magnesium, dietary fiber, choline, and potassium.
“Most multivitamin products contain many of the shortfall nutrients identified by the [U.S. Dietary Guidelines Advisory Committee] and can help Americans fill in nutrient gaps that they consistently fall short on through dietary intake only,” she said.
Wong cited a 2017 study published in the journal
Paul Garcia, a former marketing director for the vitamin company Theralogix, told Healthline that while “it’s unfair to label all multivitamins as ineffective… the brands people buy most often are junk.”
Garcia said that of the thousands of vitamin brands on the market, only a fraction go through rigorous testing and are backed by physicians who agree that these particular vitamins deliver the benefits they’re supposed to.
Vitamins mass-marketed to consumers, on the other hand, may or may not match the ingredients listed on their labels or be bioavailable — to have an active effect at the time that they enter the body — said Garcia.
“The wrong forms just don’t release the nutrients and end up passing through without delivering benefits,” he said.
“If your body can’t absorb the vitamins or minerals, then you’re just throwing money away,” he said. “Some multivitamins are about as nutritious as eating rocks.”
“There’s no substitute for food sources… [but] people don’t like the taste of all foods, nor do they want to choose what they eat based on how nutritious it is. So, they turn to supplements, or they do nothing,” he said.