June 21, 2014

Should We Be Taking Multivitamins? ~ Dr. Mary Wendt, M.D.

Dzaky Murad / Pixoto

Taking vitamins every day was always assumed to be a pretty wise thing to do.

After all, it was an easy way to ensure we were getting our vitamins, from A to Zinc as one vitamin manufacturer likes to put it.

More than half of American adults, in fact, take a multi-vitamin or supplement, spending a whopping $20 billion a year. But an editorial, “Enough is Enough: Stop Wasting Money on Vitamin and Mineral Supplements,” published in December 2013 in Annals of Internal Medicine, pretty much says it all.

We’re not getting a whole lot of health bang for our buck.

The editorial was based on three studies published in the same issue. According to the editorial, the studies found that multivitamins had no benefit in helping to prevent heart attacks, cancer or improving cognitive function in men older than 65.

Conclusions from University of Minnesota researchers went even further. They followed 38,000 women in the Iowa Women’s Health Study, beginning in 1986 when the women were around 62 years old. Data on their supplement use was collected in 1986, 1997 and 2004. According to the study published in the Journal Archives of Internal Medicine (October 2011), the results showed that women who regularly took supplements had a slightly increased risk of dying over the course of the 19-year study compared to women who didn’t take any.

One possible reason: a lot of processed food is already enriched with vitamins. A multi-vitamin is probably redundant and unable to deliver all the benefits of a whole food. The study’s authors advised that individuals reconsider whether they really need supplements. The better approach would be to emphasize a healthy diet.

However, I don’t think the issue is as simple as throwing out supplements altogether.

To get your head around this, first know there are water-soluble vitamins and fat-soluble vitamins, such as vitamins A, D, E and K. Our bodies only need miniscule amounts of fat-soluble vitamins and not every day. If we take them in excess, they get stored in our liver and fatty tissue.

Water-soluble vitamin, such as vitamin C, on the other hand, are washed out of our bodies as “expensive urine,” as some doctors like to say. Unlike fat-soluble vitamins, water-soluble vitamins need to be replaced every day.

Problems can develop when we take more fat-soluble vitamins than we need. Most of these supplements contain far more micro-nutrients than our body can utilize. Because our body stores them, they can potentially build up.

Furthermore, we don’t know how excess fat manages fat-soluble vitamins. Triathletes are 14% fat by weight. At that fat percentage and weight, we know that fat will store and release substances easily but as body weight and fat percentages increase, the behavior of the excess fat is less reliable in terms of vitamin storage and release. In this way, a person may have high levels of fat soluble vitamins, but still be vitamin deficient in their system.

This whole question of what kind of vitamin or mineral supplement we need depends highly on the individual—our age, how far north we live, the color of our skin, how much we exercise and the vagaries of our body. Female endurance runners, for example, tend to be on the anemic side.

Blood work is the only sure way to know if we have any deficiencies and need a supplement. However, blood work for vitamin levels can be unreliable.

Here are my thoughts about some of the more common supplements.


Are you a female athlete? Keep a very close eye on your iron levels. Strenuous training increases the demand for iron because it triggers a higher production of red blood cells and blood vessels. The “foot strikes” of an endurance runner on hard surfaces, along with heavy sweating, can lead to iron loss.

If you are anemic, you can get a ton of iron from whole plant foods, especially whole grains. The absorption of iron from grains and beans is regulated tightly by your body, so you will get just enough. Heme iron from meats bypass the regulatory systems of the small intestine, increasing iron levels in your body whether you need it or not (1).

In addition, we must have vitamin C in our system to absorb the iron. Plants are loaded with vitamin C, while meats don’t have any (2).

People with higher blood iron levels are at higher risk for heart disease and some cancers (3).

My advice would be to avoid iron supplementation. We can eat more whole grains to increase our iron intake in the most natural and healthy way.



Everyone must absolutely take vitamin B-12.  This water-soluble vitamin isn’t made by plants, but is found in microbes in dirt and grows in the guts of animals we eat. Nobody wants to eat dirtier food, like we would if we were still hunter-gatherers. The consequences for a B-12 deficiency can be very grave and include suicidal depression, psychotic delusions or even death.


Vitamin D

The best way to get vitamin D, technically a pre-hormone, is from sunshine—just 10 to 15 minutes a day on bare skin (no sunscreen) is all we need. Excessive sun exposure won’t cause vitamin D toxicity, but take it easy—there’s always the risk of sunburn and skin cancer.

But getting vitamin D from the sun isn’t so easy in the darker months of winter. Even when the sun is shining, it doesn’t deliver enough ultraviolet light. So I recommend to all my patients that they take a vitamin D supplement in the winter since it’s really hard to get enough of the vitamin from food sources—fortified milk and oily fish, such as herring, salmon, sardines, along with cod liver oil.

Some people need to take the supplement all year-round: those who are black, Hispanic, elderly, stay inside all the time or never leave the house without sunscreen (breast-fed infants need it, too). However, if you are of a normal weight, you could increase your sun exposure in winter months and rely on your body fat to release the vitamin D appropriately over the winter months.

Timing is important with this one. To ensure our bodies actually absorb it, we have to take vitamin D with a big meal, according to a Cleveland study.

You might wonder if you can get vitamin D from sunshine streaming through a window but unfortunately, it’s a negative on that one.

Vitamin D deficiency is often described as a major problem in the United States. One study estimates that 42 percent of Americans are vitamin D deficient. Deficiencies were often found in folks suffering from poor health and who never drink milk.

These deficiency rates are a concern because vitamin D is key in helping our bodies to absorb calcium to form bones. It also boosts immunity and controls cell growth. There’s growing evidence that vitamin D deficiency might even be linked to several chronic diseases, including heart disease and cancer.

When it comes to taking a vitamin D supplement, don’t overdo it.  Excessive amounts of this fat-soluble vitamin can prove toxic. The Endocrine Society recommends 600 to 1,000 IU for older children and teens; 1,500 to 2,000 IU for adults.  Doctors were advised that vitamin-deficient adults might need 10,000 IUs daily for two months.

With the very low rates of regular exercise in our country, vitamin D deficiency may simply be an expensive marker for a lack of routine outdoor activity. The best vitamin D is the vitamin D our bodies produce from the cholesterol in the skin when we play and work outdoors. Our brilliant bodies store that vitamin D in our healthy fat stores for future use.

I recommend taking a vitamin D/magnesium combo supplement only if testing reveals that you are still deficient in the vitamin even though you are getting outside most days. Most vitamin D deficiencies are simply attributed to a deficiency in outdoor time.



Just as our bodies cannot make vitamin D, they also can’t produce omega-3 so be diligent seeking out food that contains omega-3, like seeds and nuts. Fish, such as salmon, anchovies and trout, are higher in healthy fats, but the people with the highest levels of omega-3 fats concentrate their diets on vegetarian sources of healthy fats, such beans, nuts and seeds (3).

Omega-3 can boost our memory and mood; enhance joint and vision health; strengthen skin, hair and nails; and reduce inflammation that may lead to all kinds of bad stuff—heart disease, high blood pressure and fatal heart arrhythmias. Supplements are not nearly as effective as choosing a diet that is high in these omega-3 rich foods.



Pregnant women (or women trying to get pregnant) should supplement their diets with a multi-vitamin that includes folate—an essential vitamin that prevents birth defects such as spina bifida.


(1) Mechanisms of heme iron absorption: Current questions and controversies
World J Gastroenterol. Jul 14, 2008; 14(26): 4101–4110.

(2) The role of vitamin C in iron absorption
International Journal for Vitamin and Nutrition Research. 1989;30:103-8.

(3) http://www.medscape.com/viewarticle/502752 (requires a log-in)

(4) Dietary habits affect the susceptibility of low-density lipoprotein to oxidation.
European Journal of Clinical Nutrition. 1999 Oct;53(10):802-7.



Boston University Medical Center. “Weekly And Biweekly Vitamin D2 Prevents Vitamin D Deficiency.” ScienceDaily.Com: (October 28, 2009).

Volkov, I. Rudoy, M. Machagna, I. Glezer, U. Ganel, A. Orenshtein, & Y. Press. “Modern society and prospects of low vitamin B12 intake.” Ann Nutr Metab, 51(5):468-470, 2007.

Forrest KY, Stuhldreher WL. Prevalence and correlates of vitamin D deficiency in US adults. Nutr Res. 2011 Jan;31(1):48-54

Mulligan GB, Licata A. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin.” D. J Bone Miner Research: (April 2010).


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Editorial Apprentice: Jamie Khoo/Editor: Renée Picard

Photo: Dzaky Murad/Pixoto

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Dr. Mary Wendt, M.D