Following the Evidence: Multivitamins Revisited

multivitamin supplements
Are multivitamin supplements useless? Does the science all point to these pills being a complete waste of money and time?

This is simply not true, and you should know why.

In a letter in Annals of Internal Medicine, nutrition experts from the Linus Pauling Institute at Oregon State University, the Children’s Hospital Oakland Research Institute, Tufts University, and the Harvard School of Public Health gather scientific evidence to show that the conclusions to stop your multivitamins are just plain wrong (Guallar et al., “Enough Is Enough”).

First, be aware that multivitamins are not miracles. They can’t cure every disease, nor are they designed to do so. However, they are intended to supplement a diet that may not be reach recommended levels of all vitamins and minerals.

And this is not an usual – national surveys say that many American adults do not meet vitamin and mineral intake recommendations from diet alone: at least 90% don’t get enough vitamins D and E, 60% a low in magnesium, and about 50% are lacking enough vitamin A and calcium. Taking a daily multivitamin helps to fill many of these nutritional gaps effectively, safely, and at low cost.Multivitamins

But this campaign against multivitamin supplements has recently taken on a new life. Where did it start? Three recent publications has set new fuel for this most recent fire. But do these articles really condemn multivitamins as useless?

The first article, conducted by the U.S. Preventive Services Task Force, gathered data from vitamin studies involving more than 400,000 people. To quote the article directly: “Two large trials [with 27,658 individuals] reported lower cancer incidence in men taking a multivitamin for more than 10 years.” Although there appeared to be no overall effects on cardiovascular disease, there is no reason to discount these cancer results out of hand.

The second article was conducted as part of the Physicians Health Study (PHS II), which examined the effect of a daily multivitamin/mineral supplement on cognitive function in male physicians. The main conclusion of this study was that there were no significant cognitive health benefits in people over the age of 65 taking a multivitamin/mineral compared to those who took a placebo pill. However, as explained in the PHS II report, the subjects of this trial had a decent diet and were highly-educated men, so the benefits on cognition were not expected based on previous studies using multivitamins.

Nonetheless, previously published data from PHS II (the same study group) showed other benefits from multivitamins, including reduced risks of cancer and  cataracts. So following a conclusion that these cognitive data provide “no benefit” of multivitamin use is clearly not examining all the evidence.

woman holding pepper

The third study was a little unusual: it used a high-dose multivitamin/mineral supplement to prevent a recurrent cardiovascular event in people who already had a heart attack. The main conclusion of this study was that there was no benefit or harm of the multivitamin regimen.

However, a closer look at the data showed that people taking high-dose multivitamins showed fewer cardiovascular events (such as stroke, heart attack, etc.) versus the placebo group at every time point after the first year of the study. But the results never reached statistical significance, so an overall conclusion about the multivitamins could not be made.

Several limitations plagued this study’s conclusions. First, it was primarily designed to test the effect of chelation therapy with vitamin therapy on cardiovascular events and not just focused on multivitamins. The individuals in this study were low in number , on multiple prescription medications, and approximately 30% of them had diabetes. Additionally, almost half left the study before its conclusion!

Furthermore, this supplement was not a typical multivitamin: it contained more than the daily value (%DV) of 15 of vitamins and minerals, but contained other non-essential compounds (like citrus bioflavonoids).

Fruits on a market stand

Despite all of this, there was a result from this study that is not often discussed: of the individuals who did not take drugs to lower their cholesterol (statins), the multivitamin regiment showed a significantly lower rate for cardiovascular events versus those who took a placebo. In other words, the use of statins – while certainly of benefit to individuals who have had a heart attack – may have hidden the cardiovascular benefits of the multivitamin therapy.

If anything, the conclusions of this study should not suggest that multivitamins are “useless,” but are instead deserving of further investigation, especially in individuals who cannot take statins because of allergy or other side effects.

If we go beyond these three articles, the benefits of taking multivitamins are multifold: they supply micronutrients to those in more critical need, such as older adults, people who have poor access to fresh fruit and vegetables (and children who refuse to eat them), people who are obese, women who are pregnant or planning on becoming pregnant, and some people who are ill or injured.

Heart illlustration filled with vegetabls, logo of DOH Conference.

The fact of the matter is that multivitamin/mineral supplements are designed to supply the body with micronutrients that allow for its proper function – they are designed to keep us in good health. Any evidence that these supplements may also help decrease chronic disease risk, like in the PHS II study with respect to cancer and cataract, should be worthy of further, better designed multivitamin trials.
The Linus Pauling Institute and others have stated that research methods need to improve in order to realize the benefits of vitamin and mineral interventions for chronic disease prevention. However, until they do, we will continue to examine the totality of the evidence from supplementation studies. At the LPI, we base our recommendations for healthy living on the up-to-date scientific evidence.

Eating a healthy diet and taking your multivitamin is still a good idea — and we encourage you to ignore all the sensational headlines that tell you otherwise.

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Published by

Alexander Michels, PhD

Alexander Michels is a Research Associate and Communications Officer for the Linus Pauling Institute. He has an extensive background in the research on vitamin C, with a specialty in understanding vitamin C transport through the body. His expertise also extends to research on other aspects of antioxidant vitamin metabolism and the action of phytochemicals.