There’s been a lot of debate over the role of multivitamins in everything from cancer to heart disease to diabetes to depression. You name it, and there’s probably a study, op ed, or at the very least, a handful of blog posts in favor or against the use of multivitamins for (whatever the hot topic of the day is).

So which is it? Are multivitamins good for you? That question is a little trickier than it seems.

Generally, if you’re a healthy individual with a healthy lifestyle (meaning you eat tons of fresh, high quality produce and natural foods, exercise, and manage stress well), you probably don’t need to take a multivitamin. In fact, I often advise my own patients against multivitamins if I see that they’re living a consistent and healthy lifestyle free from any family or personal history of disease or illness.

That being said, not everyone fits into that category, which is why people take multivitamins to begin with. And as the supplement industry grows from $4 billion in 1994 to $23.7 billion in 2008 (1), it’s more important now than ever before to understand the effect multivitamins have on your health.

The Multivitamin Scare

Much of the multivitamin scare has come from a number of studies that indicate a relationship between the use of multivitamins and the prevalence of cancer. For example, in 2011 a Swedish study was published that showed a significant increase of breast cancer in women who took multivitamins (2), and in 2006 another study found a positive correlation between women who took folic acid supplements and breast cancer (3). Other studies, on the other hand, have found no link between multivitamins and cancer (4) or heart disease (5).

However, there are a few very important limitations and other things to think about, such as the sample size, the length of the study, self-reporting bias, and whether or not there was a control group involved in the study.

Most studies examining the relationship between multivitamins and illness rely heavily on self-reporting in the form of questionnaires completed by test subjects, and do not have accurate data on the dosage of the multivitamin taken. The same 2011 Swedish study (2) involved mailed questionnaires and noted that, “Because participants were not asked about multivitamin brand names, information on nutrient composition of multivitamins was not available.” According to the study, however, Swedish multivitamins generally only contain the maximum daily recommended allowance – vitamin A (0.9 mg), vitamin C (60 mg), vitamin D (5 μg), vitamin E (9 mg) (2).

Once again in 2013 (5), a study found no favorable relationship between multivitamins and cancer. That being said, the study had a high drop out rate, a smaller sample size, and only involved high-dose multivitamins and post myocardial infarction patients.

As with all things, the devil’s in the details.

Not All Trials & Studies Are Made Equal

Because clinical trials and medical studies are often subjective and rely heavily on the patient’s honesty and reliability, it can be hard to find large-scale studies involving a control group while spanning several years at the same time.

However, in November of 2012, a highly reputable study was published in the Journal of American Medical Association (6). Like many studies before, it looked at the relationship between multivitamins and cancer. It involved a sample size of 14,641 male physicians and was published under the Physician’s Health Study II. The study spanned over a decade and involved a placebo group as well as an active group. The dosage of the multivitamins was low and it is the only large-scale, randomized, double-blind, placebo-controlled trial testing the long-term effects of multivitamins in the prevention of chronic disease. (6)

The results showed that “daily multivitamin supplementation modestly but significantly reduced the risk of total cancer.” While the study was unable to determine specifically what kinds of cancer, they did find an 8% reduction in overall cancer risk (minus prostate cancer) when the physicians took a low-dosage vitamin and mineral multivitamin. (6)

What We Need More Of

I would love to see more large-scale trials and studies performed like the one by the Physician’s Health Study II. I would especially like to see more studies comparing low-dose multivitamins to high-dose multivitamins and their effect on individuals with “healthy” lifestyles versus individuals with less-healthy lifestyles. It’s imperative that physicians, along with everyone else, realize the difference between taking a high-dose vitamin versus a low-dose vitamin. Dosing is key and is still not fully understood in the world of supplements, vitamins, and minerals.

As I mentioned before, in my integrative medicine clinic,  I would not advise a healthy individual with a healthy family history to take multivitamins. If they’re getting all they need from food, then there really isn’t any point in taking supplements. However, for individuals (more often than not) who are unable to meet their vitamin requirements for whatever reason (lifestyle, work, stress, travel, illness), I would advise a low-dose multivitamin as a gap-filler to help ensure that the individual gets the missing nutrients he or she needs.

Health, as we know encompasses many different facets and many moving parts. Multivitamins is but one aspect of a whole.

Sources:

  1. Shames, Lisa, et al. Dietary Supplements: FDA Should Take Further Actions to Improve Oversight and Consumer Understanding. United States Government Accountability Office, 2009. PDF.
  2. Larsson S, et al. “Multivitamin use and breast cancer incidence in a prospective cohort of Swedish women.” American Journal of Clinical Nutrition. 2010;91:1268–
  3. Stolzenberg-Solomon R, et al. “Folate intake, alcohol use, and postmenopausal breast cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.” American Journal of Clinical Nutrition. 2006;83:895–
  4. Ishitani K, et al. “A Prospective Study of Multivitamin Supplement Use and Risk of Breast Cancer.” American Journal of Epidemiology. 2008;167:1197–
  5. Lamas G, et al. “Oral High-Dose Multivitamins and Minerals or Post Myocardial Infarction Patients in TACT.” Annals of Internal Medicine. 2013;159(12):797-805.
  6. Gaziano J, et al. “Multivitamins in the Prevention of Cancer in Men: The Physicians’ Health Study II Randomized Controlled Trial.” The Journal of the American Medical Association. 2012;308(18):1871-1880.