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Are Vitamins Dangerous?

Clifton Sheets, MD October 17, 2011Uncategorized

Wow, is that a loaded question or what? The answer is “it depends”. Like most issues in medicine, there are positive (pro-vitamin) research studies and negative (anti-vitamin) studies, so the patient and their physician need to take both into consideration when embarking on a rational supplementation program. My patients know that I am a big believer in supplements when taken in the right dose and the right form and for the right reason. So for the record I freely admit my pro supplementation bias. Your doctor may feel completely differently.

Clearly, some supplements can be dangerous, especially when taken in the wrong dosage or the wrong form. Take vitamin A for example. Ingest too much vitamin A and you can become sick and even increase your risk of lung cancer, especially if you are a smoker. Vitamin A actively competes with the potent anti cancer effects of Vitamin D in the body. Too much vitamin A can therefore potentially negate any beneficial effect of vitamin D. This is particularly true if the user is vitamin D deficient.

Beta-carotine, however, is a precursor to vitamin A and is converted to vitamin A only on demand (as the body needs it), so it is a much safer way to make sure you have adequate vitamin A available without the risk of toxicity that can occur when taking preformed vitamin A. (Warning! Cod liver oil has large amounts of preformed vitamin A, and I tell my patients to avoid it entirely to avoid vitamin A toxicity.)

On the other hand, the health benefits of having a healthy vitamin D level are extensive and well documented. To learn some of these, spend time on the Vitamin D Council website.

The Iowa Women’s Health Study has been widely quoted in the media this week. The authors contend that women who had an average age of 61 at the beginning of the study and who took vitamin supplements had a higher mortality that those who did not. The increased risk was small, about 2.5 % but statistically significant. Women who took iron and copper had the highest increased risk.

Big news indeed, but I have to ask, why didn’t these same news agencies report the results from a study published in the July 2011 issue of the European Journal of Nutrition that looked at the effect of supplementation on all cause mortality and revealed a completely different result?

This European study prospectively followed about 24,000 healthy participants for 11 years and demonstrated that long-term users of vitamin supplements had a 48% reduced risk of death from cancer and a 42% lower all-cause mortality when compared to non vitamin users. The authors of the study also noted a “sick user” component. That is, once someone became ill, they were more likely to start taking vitamins. If an author does not correct for this effect, then results can become skewed. The Iowa Women’s Study noted that supplement use increased over the time of the study. In 1986 when the study began, about 65% of the women reported taking one supplement daily. By 2004 that number had increased to nearly 85%. Could this have been a “sick user” effect?

Life Extension wrote a rebuttal to the Iowa Women’s Health Study. For those of you who want to dig deeper into the potential problems with the Iowa Women’s Health study, I suggest you read it.

I have been telling all of my male patients and all of my post menopausal (or hysterectomy) female patients for years that you do not need to take iron in your supplements unless you are documented to be iron deficient. Perhaps the biggest take away for me from the Iowa Women’s Health study is a validation of that statement for those of you who are post menopausal. Guys, you weren’t included in the study but I stand by my statement.

It is important to discuss what supplements you are taking with your doctor. Some supplements can interfere with prescription medications by making them less effective. Others can enhance the side effects of certain medications with potentially disastrous outcomes. Be sure to know the dose and frequency of your supplements so your doctor can help you make the best informed decision.

Disclaimer: My blog posts on the Prime Care website are meant for informational purposes only and are not intended to be considered as medical advice or as a diagnostic tool. Seek prompt medical attention if you have health concerns.