Over the past few decades, multivitamins have become the most popular dietary supplement in the U.S., with over one-third of the adult population now regularly taking them.  

Their use has become commonplace, in large part, due to a number of health claims about their preventative effects on chronic conditions such as heart disease and cancer.  

While there are all sorts of claims out there, many still have questions as to whether or not all the hype is real.  In order to weigh in on the debate, we’re evaluating the most current research findings to determine if multivitamins actually work.

What Are Multivitamins?

The term “multivitamin” refers to supplements that are composed of a number of different vitamins and minerals, as well as some other ingredients like herbs and amino acids in some cases.  

Collectively known as micronutrients, there are 27 different vitamins and minerals in total and each plays a vital and unique role in the human body.  They’re also known as essential nutrients because they can’t be produced by your body and instead must be obtained from dietary sources.   

Some work as signaling molecules, helping to facilitate all kinds of different bodily processes, while others aid in the production of things like neurotransmitters and amino acids.    

Most multivitamin products contain a variety of different vitamins and minerals.  However, exactly what micronutrients they contain, as well as the dosage, varies from product to product.   Multivitamins also come in a number of different forms, including chewable gummies, capsules, and powders, just to name a few.    

Do Multivitamins Work: What Does the Research Say?

From reducing the risk of heart disease to preventing cancer, multivitamins have been purported to offer all kinds of different health benefits to the average, healthy adult.  

While there are plenty of health claims out there about multivitamins, many have not been thoroughly investigated within the scientific community.  Even when it comes to the research that has been conducted, there are mixed findings — some studies suggest that they may be beneficial, while others indicate that they may have little to no effect at all.  

Multivitamins and Cognitive Function

Of the claims that have been researched, there does appear to be some promising evidence that multivitamin supplementation may help to improve certain aspects of cognitive function, especially in older folks.   

Vitamins and minerals play a central role in a number of cellular processes involved in maintaining brain function.  Research shows that increasing your intake of micronutrients may help to improve the way in which your brain works.  

More particularly, findings from several studies have demonstrated that multivitamins may help to improve certain aspects of your memory. (1) For example, a 2012 systematic review published in the  Journal of Alzheimer’s Disease evaluated 10 different trials involving multivitamins and cognitive performance. (2) The researchers ultimately found that multivitamin supplementation significantly improved participants’ immediate free recall memory.  

In addition, some research has also found that multivitamins may help to improve your mood as well.  For instance, a double-blind, placebo-controlled study published in Human Psychopharmacology investigated the effects of multivitamin supplementation on fifty random subjects age 50 – 69. (3)

The researchers ultimately found that after 8 weeks of supplementation, participants who were given multivitamins reported significant reductions in depression, stress, and anxiety, while the placebo group did not. 

Multivitamins and Cardiovascular Disease

Indeed, there is some evidence that taking multivitamins may help to reduce the risk of heart attack.(4)  For example, a 2003 study published in the Journal of Nutrition ultimately found s a significantly lower occurrence of heart attacks amongst those who regularly took multivitamins compared to those who did not.(5)

While there have been some positive findings when it comes to multivitamins and heart disease, a number of studies have also failed to find any preventative effects. (6)(7)   For instance, a 2012 randomized, placebo-controlled study involving over 14,000 participants evaluated the efficacy of multivitamin supplementation over the course of a 14 year period.(8)

At the conclusion of the trial, the researchers ultimately found no difference between the multivitamin and placebo groups, with 11 major cardiovascular events occurring per every 1,000 participants in the multivitamin group compared to 10.8 for the group taking only a placebo.  

The main take away here is that evidence for an association between multivitamin supplementation and cardiovascular disease prevention is limited.  While a small number of studies have demonstrated positive effects, many others failed to find any evidence that multivitamin supplementation helps to prevent heart disease.  

Multivitamins and Cancer

On top of warding off cardiovascular disease, millions of people also take multivitamins as a preventative measure against cancer.  

Although there are a number of claims out there, there’s actually not a whole lot of reliable evidence that taking multivitamins has any impact on cancer-related risk factors what so ever.  For example, one 2009 study involving over 160,000 older adults looked for any associations between cancer and multivitamin use. (9) 

Study participants were followed up with for an average of 8 years and all disease endpoints were recorded.  At the conclusion of the study, researchers ultimately found no significant association between multivitamin use and any type of chronic disease including bladder, stomach, lung, breast, ovarian, renal colorectal, or endometrial cancer.  

Are There Any Risk Associated With Multivitamins?

When it comes to the risks involved in taking multivitamins, it all depends on the dosage.  At relatively low dosages, there isn’t a whole lot of danger involved. If you exceed the recommended ranges, however, certain vitamins (and minerals) can become harmful.  

Water-soluble vitamins pose relatively little threat to your overall health as excess amounts can be easily expelled through your urine.  Fat-soluble vitamins, on the other hand, are more difficult for your body to discard and can accumulate when consumed in excess.    

Substances like vitamins A and D, as well as iron, can build-up in your body if you consume too much, which in turn, can become toxic to your liver, impinging on the metabolic and digestive process (amongst other things).  

Who Should Take Multivitamins?

Although there are all sorts of health claims out there, research suggests that multivitamins may not have all that much to offer the average person eating a healthy, well-balanced diet.    

With that being said, it doesn’t mean that they have no use.  There are several segments of the population that can benefit from regularly supplementing with multivitamins.  

Pregnant Women

As much as 30% of women who become pregnant eventually suffer from some kind of vitamin or mineral deficiency during their pregnancy which can ultimately lead to a number of adverse health outcomes for both mother and child alike. (10)

Researchers, however, have demonstrated that vitamin and mineral supplementation, may help to reduce the risk of a number of pregnancy-related disorders.  For instance, several studies have illustrated that folic acid supplementation may help to prevent neural tube birth defects. — folic acid is a man-made form of vitamin B9 (AKA folate). (11)(12)(13)

Other studies have also demonstrated that supplementing with vitamins B6 and B12 may help to prevent the occurrence of neurological disease in the child, as well as, reduce the risk of pregnancy-related disorders like hyperemesis gravidarum, and gestational carbohydrate intolerance. (14)(15)

There’s also a compelling body of evidence that vitamin D supplementation may help to reduce your infant’s chances of experiencing several adverse health outcomes, including preterm birth and low birthweight. (16)

should you take multivitamins

Aging Adults

The aging process can increase your chances of having vitamin deficiencies, which can, in turn, leave you vulnerable to illness and disease.  A number of experimental and clinical trials, however, have demonstrated that vitamin supplementation can help to reduce the risk of several chronic conditions.  

As we’ve already discussed, there is a sizeable body of evidence that taking multivitamins may help with cognitive functioning, which can decline later in life.  Some research even suggests that vitamins E and C can help to protect against brain-related diseases like vascular dementia.(17)

On top of protecting against cognitive decline, other micronutrients like vitamin D can help to defend against several age-related conditions like osteopenia and osteoporosis as well.  In fact, numerous studies have found that vitamin D supplementation significantly reduced the risk of bone fracture in older folks.(18)

Non-Meat Eaters

Those who don’t eat meat, such as vegans and vegetarians, may also benefit from regularly taking multivitamins.  Meats contain several essential vitamins and minerals which are more difficult to obtain in the necessary quantities from plant-based food sources.  

In fact, substances like vitamin B12, which is vital for everything from neurological function to red blood cell formation, can only be found in meat-based food sources.(19) Having a B12 deficiency can lead to several negative health outcomes including cognitive decline and anemia.  

Athletes

Another segment of the population that may benefit from taking multivitamins is athletes.  All of the wear and tear that most competitive sports put the body through can seriously deplete your micronutrient supplies, even if you’re consuming a healthy, well-balanced diet.  

In addition to leaving you feeling chronically tired and lethargic, having vitamin and/or mineral deficiencies can also impact your performance both in training and competition.    

For example, research shows that many athletes may be iron deficient, which can be especially detrimental to those in endurance-based sports.  Iron plays a central role in transporting oxygen to your muscles when you exercise and if there isn’t enough oxygen in your blood, your muscles won’t be able to optimally function, leading to cramping as well as other performance-inhibiting issues.  

Wrap Up

Although multivitamins are amongst the most popular dietary supplement in the world, evidence supporting their use in the prevention of chronic conditions like heart disease and cancer is limited.  

While a small number of studies have demonstrated significant results, most research, including several extensive multi-year trials, has ultimately failed to find any significant association between multivitamin supplementation and the prevention of chronic diseases.

Even though research findings don’t seem to support the need for multivitamin supplementation in healthy adults, the evidence that it can offer certain benefits to pregnant women, non-meat-eaters, athletes, and older folks is more convincing.