The Risks and Myths of Dietary Supplements

Dietary supplements are being purchased in increasing amounts. According to the latest statistics, roughly one in two American adults use one supplement or more - yielding an industry with $20 billion dollars in sales.

Supplements used to be taken primarily to help with nutrient deficiencies, but now Americans are popping pills to either make them feel better about their daily diet of fast food and diet coke or, as found in the Iowa Women’s Health Study, to further reduce the risk of chronic disease in already healthy individuals. However, the latest research indicates that while supplements used to fill in major nutrient gaps may be helpful, simply taking additional vitamins and minerals to boost health may not be in your best interest.

Vitamins and Minerals Linked with Increased Risk of Mortality

Research published in the Archives of Internal Medicine reviewed the effects of  the most commonly used supplements in nearly 40,000 older women (average age of 61 years). Doing so, they found that some vitamins and minerals do not provide any health benefit at all, while others may actually harm more than help.

In fact, among those that were linked with an increased risk of mortality included:

  • multivitamins
  • vitamins B6
  • folic acid
  • iron
  • magnesium
  • zinc
  • copper

While iron posed the greatest risk, calcium seemed to be protective.

The Bad and Good Effects of Calcium and Vitamin D

Yet another study published in the American Journal of Clinical Nutrition found that among the large population of women in the Women’s Health Initiative, moderate use of calcium and vitamin D reduced the risk for breast and colorectal cancers but increased the risk of cardiovascular disease and did not reduce the risk for fractures. Certainly interesting and confusing results, demonstrating just how ever changing this field is.

When It Comes to Replicating a Food's Benefits, We Have a Lot to Learn!

After years of following the tumultuous research on dietary supplements, it seems as though each person’s need (or lack thereof) is unique. Each body possesses a unique environment, one with different micronutrient balance or imbalances. Not to mention unique physiological attributes and metabolism efficiencies. All of these factors may result in absorbing too much or too little of any one nutrient. Further impact may depend on the type of nutrient (ex: fat-soluble v. water-soluble vitamins) and the specific ingredients within the supplement (ex: some calcium supplements have been found to contain mercury as they are made from coral).

The same unique environment of nutrient interaction is found within our food. This said, we have not yet gained enough of an understanding on how each and every micronutrient works together. In fact, we have not even identified each ONE of the countless micronutrients out there!

When you consider over 10,000 micornutrients exist within a single apple, you can see the complexity involved in understanding how to provide the same health benefits an apple provides within a pill.

While we may think that the vitamin A in sweet potatoes is quite nutritious (and it is!), it may not necessarily be the vitamin A causing the positive effects. Rather, it may be the combination of vitamin A and the thousands of other micronutrients with it. Yet, as we are a society of quick-fixes and immediate gratification, we choose to extract that one micronutrient and hope for the same positive effects. We certainly still have a lot to learn, as evident by the constantly changing recommendations in the health field.  

Changing Health Beliefs, Inadequate Monitoring

At one point we believed all fat was bad for us, now we are taking oil supplements and encouraging healthy fat. Case in point.

I would also point out the fact that dietary supplements do not have to go through the stringent testing procedures and randomized controlled trials that the FDA uses for drugs, rather relying on human observational studies – largely among those of us buying and taking them. While we certainly must be monitoring for the positive or negative impacts, it can be scary to think that the science is NOT yet available for many of the pills we are popping.

The advice of the researchers?

If you have a nutrient deficiency disease such as osteoporosis or if you are pregnant and want to make sure you are getting enough folic acid, then go ahead and reach for that supplement! Just be sure to get the input from a health professional.

I would love to hear your opinion on this topic!

Do you take supplements?

If so, which ones?

Do you feel safe taking them?


Bolland, M., Grey, A., Gamble, G., & Reid. I. (2011). Calcium and vitamin D supplements and health outcomes: a reanalysis of the Women’s Health Initiative (WHI) limited-access data set. American Journal of Clinical Nutrition, 94:1144–1149.

Mursu, J., Robien, K., Harnack, L., Park, Kl, & Jacobs, D. (2011). Dietary Supplements and Mortality Rate in Older Women: The Iowa Women's Health Study. Archives of Internal Medicine, 171(18): 1625-1633. doi:10.1001/archinternmed.2011.445

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