11 Facts You Need to Know About Dietary Supplements from 11 Facts You Need to Know About Dietary Supplements

11 Facts You Need to Know About Dietary Supplements

While some studies have associated multivitamin use with minor health benefits, Joe Leech, R.D., founder of DietsvsDisease.org points to a 2013 review of more than 25 vitamin supplement trials conducted by the U.S. Preventive Services Task Force, which concluded that vitamin supplements had no notable effect on the reduction of cancer risk.

“When you consider that 80 percent of vitamin supplement users are taking them to optimize health and prevent disease, you realize what a big waste of money they are,” he said. “My take is that unless you are supplementing a deficiency or particular health condition—less than 1 in 5 of users—then multivitamins are useless.”

For the majority of Americans, dietary supplements probably aren’t offering all of the health benefits they think they’re getting. Yet, for some, supplementation may be necessary. If you currently use a supplement or are thinking about starting one, these important facts can help you determine whether or not it’s worth your while.

Multivitamins may help prevent cancer...

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Physicians’ Health Study II (PHS II), the largest clinical trial of vitamin supplements to date, found that after 10 years, multivitamin users had a slightly reduced risk for developing cancer. “Until now, the only things proven to prevent cancer were stopping smoking and never starting,” said Dr. J. Michael Gaziano, a cardiologist at Harvard-affiliated Brigham and Women’s Hospital and VA Boston Healthcare, and one of the leaders of the PHS II study. “Now we know that multivitamins provide a modest benefit.” Still, the Harvard Medical School (HMS) says these results should not be overplayed…

…But you shouldn’t rely on them entirely.

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“The effect in [PHS II] is relatively small,” said Dr. William Kormos, editor in chief of Harvard Men’s Health Watch and a primary care physician at Harvard-affiliated Massachusetts General Hospital. Additionally, the study only examined men ages 50 and up who led generally healthy lives. “Compared with most people, the doctors in the study ate better diets, were more physically active, and engaged in fewer unhealthy activities. Less than four percent were smokers, and 60 percent exercised at least once a week,” HMS points out. On the other hand, the average American is overweight, sedentary and eats too much fat and sodium. It’s possible that a multivitamin could be helpful for someone with a less healthy lifestyle, but it’s also possible that it wouldn’t provide many benefits given the profound effects these unhealthful choices have on overall health.

Multivitamins shouldn't replace a nutritious balanced diet.

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Because research hasn’t proven that vitamin supplementation can offer any significant benefits, most experts agree that getting vitamins and minerals from a variety of foods that contain nutritious ingredients is a smarter and more effective strategy. “The studies of taking vitamins to prevent disease have been largely disappointing,” Kormos said. “It does not appear that a multivitamin can replace a healthy diet high in fruits and vegetables.” 

Multivitamins don't prevent heart disease.

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PHS II also examined whether or not multivitamins play a role in preventing heart disease. The results showed there was no effect, which as HMS points out, weakens the commonly argued case for “taking a multivitamin ‘just in case’ to prevent heart disease.”

Too many vitamins can make you sick.

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Just because vitamins are good for you doesn’t mean more is better. According to HMS, certain nutrients can be damaging when consumed in excessive amounts. Every nutrient has a recommended daily amount (RDA) and an upper intake level (UL), or the most that can be tolerated, but nutrient needs vary among individuals, so it’s important to talk to a doctor in order to find out how much of a certain vitamin or mineral supplement you should take. “Exceeding the RDA is not a medical problem essentially until the UL is reached, and then it can become harmful,” explains Dr. Bruce Bistrian, chief of clinical nutrition at Beth Israel Deaconess Medical Center and professor of medicine at Harvard Medical School. 

Some vitamins are more risky than others. According to HMS, if you exceed the limit for vitamin C, your body will most likely excrete the surplus. But consuming too much vitamin A, for example, may negatively affect your bone health, cause blood clotting and overstimulate your immune system. And in pregnant women it can lead to birth defects. “Many consumers are spurred to take excessive doses by overenthusiastic news stories on the potential benefits of certain vitamins and minerals,” HMS explains. “Remember, though, that the good news from the latest study may eventually prove true, or it may be refuted by other studies… It’s generally safest to wait for evidence to accumulate before jumping on the supplement bandwagon. Consider the potential risks, possible benefits and costs.”

And there are some risks involved.

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According to the U.S. Food and Drug Administration (FDA), the active ingredients in many dietary supplements can have “strong biological effects” and in certain situations can be particularly unsafe. Combining supplements with prescription and/or over-the-counter medications, replacing prescriptions medications with supplements and taking too much of a certain supplement (like vitamin A, D and iron) are all examples of circumstances that could lead to harmful or even life-threatening results. Additionally, the FDA says that some supplements can cause unwanted effects before, during and after surgery.

But in general, multivitamins are not dangerous.

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While there are certainly risks involved with consuming dietary supplements and there’s no proof that multivitamins offer any significant benefits aside from a slightly reduced risk for cancer, HMS said the results from PHS II didn’t show any evidence to support that taking a multivitamin is dangerous. In fact, Gaziano said that for many Americans it may be a good idea for preventing deficiencies. “Many Americans don’t get what they need,” he said. 

If you already eat a nutritious diet, you may not need a supplement.

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While it’s true that a majority of Americans don’t get all of the vitamins and minerals needed through food, if you do eat a nutritious, balanced diet comprised mostly of whole foods, you most likely won’t gain any benefits from supplementation. “A healthy diet still seems superior to taking a multivitamin, and if you already eat a healthy diet, there may be less overall benefit from taking the extra vitamins,” Kormos said. “If people ask me if they should take a multivitamin, I usually ask, 'Why do you think you need one?' They say, 'Well, I don’t eat this, I don’t eat that.' But a multivitamin is not going to replace the things missing from your diet. Whatever money you are spending on your multivitamin, it’s probably better to spend it at the farmer’s market or the grocery store on healthy foods.”

What about calcium and Vitamin D?

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The importance of these two nutrients is discussed often, but again, obtaining both is best done through your diet. According to HMS, foods high in calcium include low-fat yogurt, cheddar cheese, nonfat milk, canned salmon (with bones), tofu made with calcium sulfate, fresh cooked kale and even calcium-fortified orange juice. Among good dietary sources of vitamin D are, cod liver oil, swordfish, salmon, tuna and vitamin D-fortified orange juice, milk and yogurt. Ultimately, the decision to take a supplement should be based on your individual needs. “Review the specific recommendations with your doctor, because these are important health decisions,” said Dr. Meryl LeBoff, director of the Skeletal Health and Osteoporosis Center and Bone Density Unit at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School.

And what's up with specialized supplements?

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You’ve probably noticed that certain daily multivitamins are geared specifically towards men, women and older adults. According to HMS, these can be helpful in certain cases, but many times there are just “marketing gimmicks.” “Products vary widely; read the labels to make sure you get what you need while staying within safe limits,” HMS explains. “Although a June 2002 report in The Journal of the American Medical Association concluded that there is limited evidence for tailored supplements, a mild argument can be made in favor of some products designed for women and men.” For example, all women can likely benefit from a multivitamin that offers extra calcium and vitamin D, which help keep bones healthy and prevent osteoporosis; and women of childbearing age might consider a tailored supplement with extra folic acid (especially if there is a chance you could become pregnant) and iron, especially during monthly periods. 

What to Look For and What to Avoid

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If you do decide to take a multivitamin or other dietary supplement, there are a few things you should keep an eye out for when browsing the shelves. According to HMS experts, you should consider inexpensive preparations that contain 100 percent of the Daily Value for vitamin D, vitamin B6, vitamin B12 and folic acid. “Don’t waste your money on high potency, all-natural or designer vitamins,” HMS explained. Be skeptical of any product labeled with health claims printed next to the phrase “This statement has not been evaluated by the Food and Drug Administration.” Supplement manufacturers are not allowed to claim their products can prevent, treat or cure specific diseases, but they can use what HMS says are “structure-functions” that will sound impressive and promising to the average consumer. “A product may ‘build strong teeth’ or ‘improve memory’ or ‘boost the immune system,’” HMS reports. “Manufacturers can make these assertions without supplying a stitch of proof to any agency.” Ultimately, don’t forget that a daily multivitamin is more like an insurance policy. It should only serve as a supplement for a nutritious, balanced diet.