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Are vitamins and supplements putting you at risk?

When receiving a prescription medication, most people are aware there are potential side effects and risks involved. It is common to associate “natural” with “risk free.” However, many over-the-counter vitamins and supplements could be putting you at greater risk than you know.

Finding out your risks

The greatest risks of many vitamins and supplements fall into one of two categories: too much of a vitamin, and interactions with other medications. Sometimes, an “overdose” is less than you may think. The biggest culprits are often iron and calcium because many women still believe they require these supplements regardless of their current levels, and without any monitoring. Too much iron can cause thick, slow blood as well as multi-organ damage. Contrary to popular belief, iron will not improve fatigue unless your levels are low to begin with, as there are multiple causes for fatigue. Too much calcium has actually been linked to increased heart attacks and cardiac problems. Calcium overdose is not as exact, as some women can tolerate more than others depending on their past medical history and risk factors.

Certain vitamins and supplements can also interact with medications that you may be taking. For example, St. John’s Wort which is an herbal, over-the-counter supplement used for depression, can interact with the birth control pill, making it less effective and causing unintended pregnancies. High doses of vitamin C may also have an impact on birth control efficacy, however the research is limited. If you are taking any medications at all, speak with your health care provider before starting a vitamin or supplement to assure they are safe together.


Many people consume a daily multivitamin on the belief that they are not only doing no harm, but that they must be doing good. However, the evidence does not support this practice for the general public. A 2013 review of randomized, controlled trials by the U.S. Preventive Services Task Force revealed little to no benefit of vitamin supplementation on cardiovascular health, or cancer prevention. Multivitamin use also did not reduce mortality (meaning that they didn’t prevent death). People who should consider taking a daily multivitamin include vegans, women who are either trying to conceive or could possibly get pregnant, people who have had gastric bypass surgery, those suffering from alcohol dependence or those with diagnosed malabsorption. For the most part, however, multivitamin use is safe as most vitamin levels are well below the recommended daily intake and most vitamins (but not all) get excreted in the urine in excess. With that said, studies have found some vitamins to be watchful of — vitamin A during pregnancy has been linked to birth defects, excess vitamin C has been linked to kidney stones, beta-carotene can increase a person’s risk of lung cancer if he is a smoker and excess vitamin E has been linked to increased mortality. Essentially, if you do not fit into one of the above categories for recommended daily multivitamin use, even if you are not doing any harm, the evidence currently suggests that all you’ll have is expensive urine.

What should you take?

It is always beneficial to speak with your physician about your health concerns. If you are planning to conceive, a multivitamin with at least 0.4 mg of folic acid is recommended three months before trying. If you are at risk for having a baby with spina bifida, such as a family history, 4 mg of folic acid a day is recommended. As well, almost everyone in the northern hemisphere is vitamin D deficient in the winter months. In general, daily supplementation of 400-800 IU in children, 1000 IU in adults, and 2000 IU in the elderly is recommended. If you have dietary concerns, fatigue or any other concern that leads you to believe a supplement may help, speak with your physician about testing values if possible, as well as the risks and benefits.

Always remember, nothing that you put in your body is risk free, regardless of whether or not it is natural.

More on vitamins and your health

How much calcium do I need?
Vitamin D and bone health: what you need to know
The best supplements to take as you age

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