Multivitamins are regularly used by about half of all Americans, yet their need has been hotly debated for years.
Some headlines question the benefits of multivitamins, while others even warn against their use, declaring “you’re better off” without multivitamins. Before you begin tossing out your multivitamins, here’s what you need to know.
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Are Multivitamins Good for You?
The vitamins and minerals found in multivitamins are undoubtedly healthy, yet the answer to the question about multivitamins is a bit more complicated.
Only 10% of adults eat enough fruits and vegetables, and the average American diet is consistently low in multiple essential nutrients, including vitamin D, calcium, vitamin E, potassium and magnesium. So, why is there controversy around multivitamins?
The debate comes from studies that suggest multivitamins won’t help you live longer or prevent disease. However, it’s important to keep in mind that most studies on multivitamins have been observational, meaning that they compare people who take multivitamins with others who do not.
What’s referred to as the “healthy user effect” also needs to be considered. People who use multivitamins tend to have healthier diets and lifestyles, including lower body weights, less smoking and more exercise compared to those who do not take multivitamins. This makes it tough to isolate the impact of the supplements compared to other healthy behaviors.
On the other hand, there’s a “sick user effect.” Individuals with a chronic disease often start taking a multivitamin. When they’re a part of studies, this links the supplements to poorer health and makes the multivitamins seem less helpful than they truly are.
These observational studies also do not take into account the different compositions of multivitamins, which can vary significantly since there are no standards or regulations defining multivitamins.
[SEE: Nutrition Recommendations You’re Probably Falling Short On. Here’s How to Fix Them]
Do Multivitamins Work?
The evidence demonstrating the benefit of multivitamins has been mixed for years. The latest investigation of three large studies that tracked nearly 400,000 healthy U.S. adults for over two decades found no association between regular multivitamin use and lower risk of death.
The analysis found that people who took daily multivitamins did not have a lower risk of early death overall, or from cancer, heart disease, or cerebrovascular diseases (diseases of the brain’s blood vessels).
In fact, people who took multivitamins daily had a 4% higher all-cause mortality risk (the probability of death from any cause) than those who didn’t take them.
Even so, the researchers concluded that they couldn’t rule out the possibility that daily multivitamin use may be associated with other health outcomes related to aging.
[See: 10 Superfoods for Older Adults.]
Additionally, large clinical trials contradict these observational studies, says Taylor Wallace, CEO of the Think Healthy Group and adjunct clinical associate professor in the school of medicine and health sciences at George Washington University, who pointed out the limitations of these studies.
“I think when you see multivitamins causing a detriment to something like ‘all-cause mortality’ that it should raise a red flag that the analyses might be missing something since many lifestyle factors generally associated with intake of multivitamins are well known to improve longevity and decrease all-cause mortality,” he says.
Wallace says all-cause mortality in itself is kind of a weird measure with nutrition observational studies. For example, if you drink too much alcohol and drive, a multivitamin isn’t going to decrease your risk of mortality, he says.
“I also think it should raise a red flag when studies show multivitamins prevent cancer and cardiovascular events and death — the two major killers of adults in the U.S. — but then somehow increase all-cause mortality. It doesn’t make much sense.”
Health Benefits of Multivitamins
Diseases, like rickets and scurvy, which are caused by nutrient deficiencies are now rare in the U.S. However, Wallace says inadequate levels of certain nutrients are quite common and these insufficiencies can increase vulnerability to illness and chronic diseases, such as cancer, heart disease and Type 2 diabetes.
It’s been more difficult to document the specific benefits of taking a multivitamin. Two large long-term clinical trials suggest a potential role of multivitamins in disease prevention, although the evidence is not a total slam dunk, Wallace says.
The Physicians’ Health Study II tested four supplements, including a multivitamin, on the prevention of certain diseases among nearly 15,000 male physicians over the age of 50. Over an average of 11 years, the study found multivitamin use decreased risk of cancer by 8% and cataracts by 9% compared to those who took a placebo.
The COSMOS trial assessed the shorter-term benefits of multivitamins on the prevention of cancer and cardiovascular diseases in more than 21,000 people. Over an average of 3.6 years, the study revealed a statistically significant reduction in new lung cancer cases. The study failed to show the effects of multivitamin use on total cancer or cardiovascular disease, although Wallace says the relatively short time the study took likely limits its ability to detect any small to moderate effects on cancer rates.
Additional studies suggest multivitamin use may slow down vision loss from age-related macular degeneration, and they may slow cognitive aging by about two years in older adults, indicating potential benefits for memory and cognitive function.
Can Multivitamins Be Harmful?
The headlines warning about the dangers of multivitamins need context. The issue only involves high amounts of certain nutrients and for people with specific health risks.
For instance, beta carotene can protect against cancer if it’s absorbed from fruits and vegetables. Beta carotene is the orange-hued compound that gives carrots a distinctive color and health benefits. However, this precursor to vitamin A could increase the risk of lung cancer in people who smoke when ingested in high doses for an extended period of time.
The U.S. Preventive Services Task Force recommends against taking beta carotene or vitamin E for the prevention of cardiovascular disease or cancer.
Just like reading the nutrition facts label on food products, it’s important to read the supplement facts label on multivitamins. Wallace says to be wary of products that provide significantly more than the daily value for various micronutrients, especially the fat-soluble vitamins A, D, E and K, as well as iron. Make sure to take a good look at the nutrition label to prevent excessive intakes.
“If you’re worried about getting too much of a good thing, data shows that frequent multivitamin use virtually eliminates many micronutrient inadequacies and rarely causes excessive intakes, or the level above which the risk of adverse health effects begin to increase,” he says. “However, data also shows multivitamin users are more likely to take other dietary supplements products, and excessive intakes occur more easily when two or more dietary supplements contain the same nutrient.”
Should You Take a Multivitamin?
“While a multivitamin isn’t a substitute for a healthy diet and lifestyle, a multivitamin can help fill nutrition gaps,” says registered dietitian nutritionist Vanessa King, a spokesperson for the Academy of Nutrition and Dietetics. With Americans continuing not to eat enough fruits, vegetables, whole grains and calcium-rich foods, King says a multivitamin may be helpful, although she emphasizes that it’s a supplement, not a substitute.
While a balanced diet is the optimal source of essential nutrients, certain populations may benefit from taking a multivitamin:
— People who are planning to get pregnant or are pregnant or lactating
— Older adults who can experience reduced nutrient absorption and appetite
— Those with nutrient absorption issues, including people with gastrointestinal illnesses, heavy alcohol users and those on certain medications
— People on restrictive diets, including people limiting calories and avoiding certain foods, potentially vegans and vegetarians
“I recommend third-party testing to verify what you’re buying because supplements do not undergo the same FDA testing as pharmaceuticals and food products,” King says. “Look for a label from the U.S. Pharmacopeia (USP) or NSF International on the package. Research has found that some supplements may have more or less than the amount mentioned on the label.”
In addition to the USP or NSF seals to ensure safety, choose a multivitamin based on your age, sex, life stage and health goals, from prenatal and immune support to eye health and athletic performance.
“I stick with those that have more than 50% of the daily value (DV) for your vitamins (vitamins A, C, D, E, and K, thiamin, riboflavin, niacin, pantothenic acid, vitamin B6, folic acid, and vitamin B12), iron, zinc, iodine and selenium, as well as small amounts (more than 10% of DV) for calcium, magnesium and choline. Calcium, magnesium, and choline are bulky and it’s hard to get them into one pill with all those other nutrients. For most of us, it doesn’t hurt for the multivitamin to contain two to 10 milligrams of lutein/zeaxanthin for additional eye health.”
While excessive intake of certain nutrients through multivitamins has been documented, it underscores the importance of reading the label and talking with a registered dietitian about your supplement regimen, Wallace says.
“Taking a supplement every day will not let you off the hook when it comes to eating well, and multivitamins aren’t a magic pill nor a substitute for a healthy lifestyle. Their purpose is to fill nutritional gaps that you may not know exist. That’s why I take one every day, just in case,” says Wallace.
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Should You Take a Multivitamin? originally appeared on usnews.com