Does Your Daily Multivitamin do More Harm than Good?

vitamins

We originally wanted to write an article about which multivitamins are best for healthy young people. But as we dug deeper into the topic, our research showed that a daily multivitamin is almost never beneficial and might even be harmful.

Too busy to read the whole article? [2000 words, a 9-minute read] Here are the takeaways:

  • The medical community agrees that healthy people do not need multivitamins.
  • Studies of multivitamin supplementation show increased risk of some diseases in those who take them.
  • The Medical literature has documented specific downsides to supplementing with Vitamins A and E, and calcium.
  • You probably don’t need a multivitamin; if you have symptoms related to malnutrition, consult a doctor.

If you’re anything like me, taking vitamins was a part of your daily childhood routine. Though, in truth, I cared more about which flavor Flintstone chewable I got than about what that mystery Barney/Fred/Wilma actually had in it.

As I outgrew my beloved Flintstones chewies, my vitamin usage dwindled and stopped through high school and college. But, by the time I made it into graduate school, I started getting paranoid about my health and wondered if I should begin taking vitamin supplements again.

As a Ph.D student in Molecular Biology, I’m no stranger to doing in-depth research, so I started researching vitamin supplements to determine which ones were worth prying open my (very) tight wallet for.

I was surprised by what I found. You see, nutrition research can often be a contentious field, with experts and researchers going back and forth on what’s really “good for you.” Which is why I was so surprised that peer-reviewed, placebo-controlled scientific studies have consistently shown that vitamin supplements are not only unable to prevent disease, but in fact may increase your risk of cardiovascular disease, cancer, and mortality.

In fact, the evidence is so concrete that in a public statement, the National Institutes of Health (NIH)1 said, “present evidence is insufficient to recommend either for or against the use of [multivitamins/minerals] by the American public to prevent chronic disease”.

 “present evidence is insufficient to recommend either for or against the use of [multivitamins/minerals] by the American public to prevent chronic disease”.

Regan Bailey—a nutritional epidemiologist in the Office of Dietary Supplements at the NIH—futher elaborated, “people have very strong beliefs about these products and I don’t know where they are getting their information… It’s not from the doctors. The majority of scientific data available do not support the role of dietary supplements for improving health or preventing of disease”.2

And yet, half of Americans take vitamin supplements today. Half. Besides the obvious role of marketing, why do so many of us allow ourselves to believe that vitamins are good for us with zero proof? Have we become a society that believes we can correct an unhealthy lifestyle with a daily pill?

Why we need vitamins and the downside of getting too much

We’re using the term “vitamin” here to refer to the organic compounds needed for your body’s proper function. For example, “vitamin A” is actually a group of organic fat-soluble compounds used in the eyes to maintain good vision. But we’re really also talking about minerals and inorganic compounds like calcium or potassium that serve similar necessary functions in the body.

There’s no denying that prolonged deficiency of certain vitamins can lead to illness and disease. The real question, though, is whether vitamin supplements are necessary for healthy individuals.

In the United States, if you eat a diet full of fruits, vegetables, and whole grains, you are most likely getting your full daily value of essential vitamins and minerals. And even if you eat a terrible diet, many types of processed foods are fortified with vitamins and minerals.

If you are taking a vitamin supplement in addition to eating well and consuming some fortified foods, you may be ingesting multiple fold over your recommended daily value (DV) of certain vitamins.

Multivitamins as a drug: an analogy

To visualize the downside of overdosing on vitamins, let’s consider an analogy.

Would you take a powerful antibiotic every day “just in case”?

Well, sure you would, if you lived in an area infested with malaria. In such a situation, you might take a daily dose of the anti-malarial antibiotic doxycycline. But, would you want to take doxycycline in a malaria-free region? Probably not, unless you’re a fan of daily nausea, headaches, and let’s just say…digestive discomfort.

What happens when you apply that same benefit vs. side effects analysis to your daily multivitamin?

If you knew you were at risk for a vitamin deficiency due to a poor diet or a preexisting medical condition, then you would perhaps consider supplementing to address that deficiency. But, if you were otherwise healthy and didn’t suspect a vitamin deficiency? The downsides of multivitamins could easily outweigh the benefits.

Multivitamins often contain 100% or more of your daily recommended value of Vitamin A, Vitamin C, iron, and calcium. Unless you aren’t consuming any nutritional food at all, you simply don’t need these supplements.

The downsides of supplementing with multivitamins

A very popular 2004 meta-analysis study from the University of Copenhagen examined the ability for antioxidant supplements (Vitamins A, C, E, and beta-carotene) to prevent gastrointestinal cancer in over 170,000 individuals. Their results found that these supplements were not only unable to prevent cancer, but actually significantly increased overall mortality by 6 percent.3

Another study by the same authors three years later found that in over 232,000 patients treated with another antioxidant supplement (Vitamins A, E, and beta-carotene) mortality rates were again significantly higher than in patients who received no supplement.4

Lastly, a 2011 study of over 38,000 older women found that women who used multivitamin supplements had increased mortality rates compared to women who did not use them.5 The fact that three separate studies with over 440,000 total participants show there is a significant increase in mortality associated with multivitamin supplement use should concern anyone who pops these pills daily.

Additionally, a 2007 study showed that multivitamin supplements (Vitamin C, E, beta-carotene, selenium, and zinc) increased the risk of skin cancer in women.6

Learn how we interpret and evaluate studies, and how you can too.

While it appears that multivitamin supplements may have alarming effects, can single vitamin supplements have deleterious effects, as well?

The downsides of supplementing with Vitamin A/beta-carotene

Vitamin A is a fat soluble nutrient that can be obtained either through animal sources or through fruit and vegetable sources as “pro-Vitamin A” (most commonly beta-carotene). The body then converts pro-Vitain A into Vitamin A through digestion. They’re basically the same thing from a practical standpoint.

Vitamin A is found in bright yellow and orange fruit and vegetable sources such as sweet potatoes (1 cup = 380% DV), butternut squash (1 cup = 300% DV) and carrots (1 medium = 200% DV). It can also be found in dark leafy vegetables such as kale (1 cup = 130% DV), spinach (1 cup = 50% DV) and broccoli (1 cup = 10% DV). Fortified sources, like most breakfast cereals, contain ~10% DV.

Unfortunately, beta-carotene (pro-Vitamin A) has been shown to increase the incidence of lung cancer in two separate studies. In a 1994 study, it was found that beta-carotene supplementation increased the incidence of lung cancer in male smokers by 18 percent.7 In 1996 the Beta-Carotene and Retinol Efficacy Trial (CARET) tested the combination of supplemental beta-carotene and Vitamin A in men and women who were at high risk of developing lung cancer due to asbestos exposure or an extensive smoking history, respectively. This study found that with supplementation there 28 percent more lung cancers developed and 17 percent more deaths occurred than those in the control. In fact, that study was discontinued 21 months early due to the obvious danger of this supplement combination in this patient demographic.8

The downsides of supplementing with Vitamin E

Vitamin E is a fat-soluble nutrient that can be found in wheat germ (1 tbsp = 100% DV), various nuts and seeds (1 serving = ~35% DV), as well as dark leafy vegetables and seed/vegetable oils. You can also obtain this vitamin through fortified sources like cereals (1 serving = ~40% DV). While it appears there are more limited sources of Vitamin E, studies with its supplementation have been shown to be concerning.

A 2005 study found that Vitamin E supplements had no effect on preventing cancer or cardiovascular disease, but actually increased the risk of heart failure.9 A separate study that same year found that in over 135,000 patients, supplemental Vitamin E was significantly correlated to increased mortality rates. The authors even went as far as to conclude that Vitamin E supplementation should be avoided.10 Lastly, a 2011 study in over 35,000 men reported that Vitamin E supplementation significantly increased the risk of prostate cancer.11

The downsides of supplementing with Calcium

Nearly every multivitamin supplement contains calcium and calcium supplements are highly recommended to women. The CDC has reported that 10% of women over 50 are afflicted with osteoporosis of the hip and so increasing calcium intake has become a concern for many women as they age. Great natural sources of calcium include yogurt (1 cup = 20-45% DV), dairy milk (1 cup = 30% DV) and tofu (1/2 cup = 45% DV). Some types of fish and various vegetables also contain calcium. Fortified sources such as soy or almond milk (1 cup = 50% DV) and cereals (1 serving = 25-100% DV) are easy ways to increase your intake.

Calcium supplements can be found not only in tablet form, but in tasty chocolate and caramel chewable form, as well. So can these supplements help protect your bones as you age? Not only have some studies shown that increased calcium intake does not protect you from bone loss, but can also increase your risk of cardiovascular disease. A 2007 study found that not only were calcium supplements unable to protect women or men from hip fracture, but that they actually put patients at increased risk for fracture.12 Results from four separate studies looking at the relationship between calcium supplementation and cardiovascular disease (CVD) indicate that calcium supplements are associated with higher CVD-related deaths.13,14,15,16

Conclusion: Treat vitamins and supplements with the same care you would treat any other drug

It’s just so easy to think of vitamins as a “nutritional insurance plan” and so many people take them that everyone thinks they must do something good, or at least do no harm. But, would you take a tylenol every day just because it didn’t make you feel worse?

Doctors are catching on to the research and starting to advise against vitamin supplementation.

With that being said, remember that I specifically researched the effects of vitamin supplementation on healthy adults, aged 25-35. Although I didn’t see any studies in the course of my research that specifically said children or seniors benefit from a daily multivitamin, I also didn’t look at those age groups in depth.

Also, just like any drug, vitamins can and should be prescribed for special cases. If you’re pregnant, your obstetrician/gynecologist will probably advise you to supplement with folic acid and if your doctor suspects you have a vitamin deficiency due to poor diet or a particular physiological problem, she might also advise you to supplement.

But for the rest of us? I simply could not find any real benefits to taking vitamins and there appear to be some pretty significant risks to healthy individuals or to those at risk for cancer or heart disease.

Your next action: stop taking multivitamins

  • As long as you are eating a diverse and healthy diet, it appears the “necessity” for vitamin supplements is unfounded. If you believe you are deficient in certain vitamins, increasing your consumption of natural sources is unarguably the best way to resolve the issue.
  • If you have more serious symptoms, consult a doctor. If they think you may have a deficiency, they may recommend a blood draw for nutritional screening or refer you to a licensed nutritionist or registered dietitian.

References:

  1. http://www.ncbi.nlm.nih.gov/pubmed/17332802
  2. http://consumer.healthday.com/cancer-information-5/mis-cancer-news-102/with-benefits-unproven-why-do-millions-of-americans-take-multivitamins-673173.html
  3. Bjelakovic, et al. (2004) “Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis.” Lancet: 364(9441), 1219-28.
  4. Bjelakovic, et al. (2007) “Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis.” JAMA: 297(8), 842-57.
  5. Mursu, et al. (2011) “Dietary supplements and mortality rate in older women: the Iowa Women’s Health Study.” Arch Intern Med: 171(18), 1625-33.
  6. Hercberg, et al. (2007) “Antioxidant supplementation increases the risk of skin cancers in women but not in men.” J Nutr: 137(9), 2098-105
  7. [No authors listed]. (1994) “The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group.” N Engl J Med: 330(15), 1029-35.
  8. Omenn, et al. (1996) “Risk Factors for Lung Cancer and for Intervention Effects in CARET, the Beta-Carotene and Retinol Efficacy Trial” JNCI J Natl Cancer Inst: 88(21), 1550-1559
  9. Lonn, et al. (2005) “Effects of long-term vitamin E supplementation on cardiovascular events and cancer: a randomized controlled trial.” JAMA: 293(11), 1338-47.
  10. Miller, et al. (2005) “Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality.” Ann Intern Med: 142(1), 37-46.
  11. Klein, et al. (2011) “Vitamin E and the Risk of Prostate Cancer: The Selenium and Vitamin E Cancer Prevention Trial (SELECT).” JAMA: 306(14), 1549-1556.
  12. Bischoff-Ferrari, et al. (2007) “Calcium intake and hip fracture risk in men and women: a meta-analysis of prospective cohort studies and randomized controlled trials.” Am J Clin Nutr: 86(6), 1780-1790.
  13. Michaëlsson, et al. (2013) “Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study.” BMJ: 346, f228
  14. Xiao, et al. (2013) “Dietary and Supplemental Calcium Intake and Cardiovascular Disease MortalityThe National Institutes of Health–AARP Diet and Health Study.” JAMA Intern Med.: 173(8), 639-646.
  15. Bolland, et al. (2010) “Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis.” BMJ: 341, c3691
  16. Kuanrong, et al. (2012) “Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study (EPIC-Heidelberg)” Heart: 98, 920-925.