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The Truth About Multivitamins


Find out if your daily vitamin can really work wonders for your health

By Ryan White


Vitamins and dietary supplements have never been more popular in this country — more than half of Americans are currently taking some form of supplement. In fact, they’re so popular that American consumers spent nearly $27 million on supplements in 2009, according to Consumer Reports. Each year, a new “it” vitamin or supplement seems to catapult to stardom on the back of one study before toppling under the weight of another. The conflicting evidence can be particularly bewildering for consumers who simply want to know whether or not taking a daily multivitamin is good for their health.

Supplements vs. Healthy Diet

The headlines are attention grabbing: "B12 Deficiency Can Lead to Cognitive Decline," "Excess Vitamin E Ups the Risk of Prostate Cancer." It seems as if one study reports that women who took multivitamins for over 15 years had lower odds of colorectal cancer than their counterparts, while another observational study claims that women ages 55 and older who took multivitamins were at higher risk of dying than those who didn’t. Some studies point to vitamin D as a way to strengthen bones, boost the immune system and reduce chronic disease risk. But doctors reviewing the research have subsequently questioned vitamin D’s ability to prevent bone fractures, and found no evidence that vitamin D can reduce the risk of cancer. For the average consumer, deciding which studies carry weight can be overwhelming. 

So, do daily multivitamins have genuine health benefits? “We no longer have a one-size-fits-all answer,” says David L. Katz, MD, founding director of Yale University’s Prevention Research Center. “Studies have shown benefit from multivitamins, but some have shown potential harm, so we can no longer invoke the ‘At least it couldn’t hurt’ mantra.”

Experts do tend to agree on one thing: A multivitamin is no substitute for a healthy diet. A balanced diet is the best way to ensure that your body is getting the full range of essential vitamins and nutrients it needs — plus good-for-you extras, like fiber. If you’re eating plenty of whole grains, fruits and vegetables, you’re most likely getting the nutrients you need (especially when you consider that many foods sold in supermarkets are fortified with additional vitamins, making vitamin deficiencies even less likely). And there’s no health advantage to getting more than your recommended daily amount of vitamins and nutrients; doing so may cause complications, including nausea, vomiting, and diarrhea, as well as other, more serious health problems.

But what about those of us who aren’t munching on fruits and vegetables throughout the day, or don’t always eat balanced meals? For certain people, vitamins can be a good way to supplement meals and fill in any dietary gaps. However, rather than reaching for a multivitamin, you may be better off taking specific supplements where your diet falls short. For example, a vegetarian diet may lack B12 (the vitamin found in animal-based foods that helps your body make blood cells and maintain a healthy nervous system), so a B12 supplement might be beneficial. Doctors often recommend that women who are pregnant (or trying to get pregnant) take prenatal vitamins and a folic acid supplement — the latter has been shown to reduce the incidence of defects of the brain and spinal cord in babies. For seniors, vitamin D supplements can guard against osteoporosis and lower one’s fall risk of breaking bones during a fall. For the most part, however, the benefits of a particular vitamin or supplement vary from person to person. 

“Most of us benefit from extra omega-3, vitamin D and perhaps a probiotic,” Katz said. “Those who eat no animal products may need supplemental B vitamins. Those who eat few fruits and vegetables may benefit most from a whole-food-based supplement made from concentrated fruits and vegetables. I tailor my supplement advice to my patients specific circumstances.” 


Disease Prevention

Beyond fortifying the diet, many people look to multivitamins to lower risk of disease. While most researchers say there isn’t enough evidence yet to say whether regularly taking a multivitamin prevents chronic diseases, some new but limited evidence is trickling in. In a widely publicized 2012 study published in the Journal of the American Medical Association, researchers found that a daily multivitamin modestly reduced the incidence of cancer by about 8 percent compared to the placebo in a randomized trial of more than 14,000 older male physicians.

“Although the main reason to take multivitamins is to prevent nutritional deficiency, these data provide support for the potential use of multivitamin supplements in the prevention of cancer in middle-aged and older men,” the study’s authors concluded.

However, there’s still not enough evidence for most doctors to conclude that a daily multivitamin will significantly lower your cancer risk — or your risk of heart disease and other chronic health problems. In contrast, “the evidence is clear that eating well, being active, not smoking, and controlling one’s weight can reduce the lifetime risk of all major chronic disease — heart disease, cancer, stroke, diabetes, dementia — by roughly 80 percent,” Katz said. “That’s the basket to put your eggs in.”


Choosing the Right Vitamin

While there may not be overwhelming evidence to back the heath benefits of multivitamins, for most people, a multivitamin that carries 100 percent of the recommended daily allowance is a safe supplement to a healthy lifestyle.

If you are choosing a multivitamin, it’s important to find one that’s right for you — different multivitamins contain different doses of nutrients that best suit the nutritional needs of men, women, children and seniors. Remember to check for a seal of approval from the United States Pharmacopoeia or another trustworthy group (which means the manufacturers of the product have submitted to voluntary testing to ensure their product meets certain standards). Do thorough research when you’re looking into a multivitamin — read the labels carefully, and watch out for claims that seem too good to be true.

And don’t use a daily multivitamin as an excuse for bypassing the fruits and vegetables at the supermarket. “My key principles are: Remember it’s a supplement, not a substitute,” Katz said. “The focus on eating well overall must be primary.”

Ultimately, your doctor is your best resource when considering a multivitamin or other supplement — he or she will be able to tailor a vitamin or supplement regimen that address your particular lifestyle and health needs, and answer any questions you might have.


Published April 9, 2013. 


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