Multivitamins — they’re a contentious topic. Some healthcare professionals believe they only make your urine more expensive while others believe they offer benefits, especially for people who don’t eat a nutrient-dense diet. What do multivitamins do for you? Most importantly, are they in some way harmful?
It’s always better to get your vitamins and minerals by eating a healthy diet rather than swallowing a pill. The reality is you don’t KNOW what’s in a multivitamin or other supplement, thanks to the way the FDA regulates, or doesn’t regulate supplements.
About a year ago, I subscribed to a service that tests a variety of commercial supplements to see if they’re pure and contain the concentration of active ingredients they say they do. I was surprised to find that some contained only a portion of what was on the label and also had other “surprise” ingredients like heavy metals. So, you really have to buy from reputable companies that use independent testing firms to verify their contents.
Although some supplements may be beneficial for certain individuals, I’m not a fan of multivitamins for the average person for a number of reasons. Many years ago, my husband and I took a multivitamin each day. After all, what harm could it do? But after reading studies that have come out over the last few years, we’re glad we tossed the multivites.
Let’s look at WHY you might want to rethink your multivitamin strategy.
What Do Multivitamins Do for You?
You might think multivitamins are a cheap insurance policy, a way to make sure you’re getting the nutrients you need. Most of us don’t think of them as a being harmful. After all, these vitamins and minerals, substances your body recognizes and needs, right? Yes, but it’s all about balance.
For example, you NEED vitamin C. Humans are one of the few animals, other than guinea pigs and monkeys, who can’t make vitamin C and have to get it through diet. In fact, you need to get most vitamins through diet because your body can’t make enough of them. However, that doesn’t mean you need the amount you get from taking a supplement.
It’s about balance. For example, calcium, zinc, copper, and magnesium are all similar in structure. If you take too much of one, it can interfere with the absorption of the others. So, you wouldn’t want to take a high-dose supplement of one, as it can reduce the availability of another. For example, zinc reduces the absorption of copper. Back in the days that denture creams were high in zinc, people sometimes developed life-threatening deficiency of copper due to competition for absorption.
Most of the studies looking at the impact vitamins have on health and mortality are observational studies where researchers observe multivitamin users and people who don’t take them and see how their health changes over time. That’s not the best way since so many other factors can influence the results, yet it’s not easy to do the “gold standard” type of study — a randomized, double-blind, controlled trial for reasons I won’t go into here.
Taking a Multivitamin May Not Lower the Risk of Chronic Health Problems
Of the observational studies that are out there, most don’t suggest that taking a multivitamin lowers the risk for disease. One of the biggest ones was the Iowa Women’s Health study. For this study, researchers followed women who took a multivitamin and those who didn’t for almost 20 years.
The outcome? Taking a multivitamin didn’t seem to lower the risk of the biggest killers — heart disease and cancer. That’s partially why people take them, right? The news gets worse. Women who took multivitamins had a higher overall mortality relative to those who didn’t.
What if there were a relatively large randomized, double-blind, controlled study, the “gold standard” type looking at multivitamins and their impact on health. Despite the difficulty of carrying out such a study, The Physicians’ Health Study rose to the task in 1997. In this study, researchers followed almost 15,000 middle-aged physicians for almost 10 years. The results? Taking a multivitamin didn’t lower the risk, in this population, for stroke or heart attack.
High Doses of Some Vitamins May Be Harmful
Some multivitamins contain two to three times the amount of vitamin A you need in a day. According to the Harvard School of Health, getting three times the recommended daily value of vitamin A may increase the risk for osteoporosis and birth defects. Plus, a form of vitamin A in some multivitamins, called beta-carotene, was linked with a higher risk of lung cancer in smokers. Note: This doesn’t apply to natural beta-carotene in fruits and vegetables.
If you have liver disease or drink large quantities of alcohol, you’re at greater risk for liver toxicity if you take too much vitamin A. You also find vitamin A in high quantities in cod liver oil, which is why you don’t want to guzzle the stuff. Who would want to anyway? Yuck!
Taking megadoses of vitamin C can lead to diarrhea and increases your risk for kidney stones. Despite what Linus Pauling thought, vitamin C at high doses doesn’t prevent the common cold, although it might shorten its duration by a day or so.
Watch Out for Vitamin E Too
Vitamin E is another one you’re better off leaving on the shelf. At one time, there were high hopes that vitamin E would lower the risk for heart disease, cancer, and Alzheimer’s disease due to its antioxidant activity. Turns out those studies were poorly conducted. A few better trials dashed those hopes and even showed taking vitamin E in supplement form may be harmful.
One problem with the vitamin E story is multivitamins contain only one “isoform” of vitamin E. In its natural state, as you find it in foods, there are a total of 8 isoforms, 4 tocopherols and 4 tocotrienols. It would be interesting to know whether taking a supplement with all 8 isoforms would have changed the outcome.
The Good and Bad about Folate
B vitamins are a group of vitamins important for energy metabolism but there are problems with taking too much of these too. The biggest concern is folate, a type of B vitamin. Folate is a strange animal. In certain circumstances it appears to lower the risk for certain types of cancer while in others it seems to fuel its growth.
How can you explain the strange behavior of folate? Research suggests that if you’re young and healthy, taking in lots of folate seems to lower the risk for certain cancers, including cancer of the pancreas, esophagus, and bowel. BUT if you happen to have pre-malignant cells hiding somewhere in your body, supplemental folate may actually speed up its growth rate.
A number of people have pre-malignant colon polyps that might be negatively impacted by taking supplemental folate. The one group of people who need extra folate are women who plan on becoming pregnant. Folate supplements lower the risk for a type of serious birth defect called a neural tube defect, a devastating condition that affects an unborn baby’s brain and spinal cord.
The rest of us should be getting folate from food sources. Green, leafy vegetables are one of the best sources and many foods, including most packaged cereals are fortified with folate. In reality, the type of “folate” in fortified foods is a slightly different form called folic acid. Unlike folate from food sources, folic acid may not be as readily accepted by our bodies.
You should eat lots of NATURAL folate from sources like vegetables, but avoid fortified sources and supplemental folate and that includes the folate in multivitamins.
Take the Whole Food Approach
Take the whole food approach to getting your vitamins and minerals. When you eat whole foods, particularly fruits and vegetables, you get a mixture of healthy components, including phytochemicals that have anti-inflammatory activity as well as fiber, minerals, and vitamins. That doesn’t mean there aren’t certain situations where you may benefit from a multivitamin.
Some examples of situations where you might need a multivitamin is if you’re
- Eating a very low-calorie diet
- Consuming a restricted diet
- Have a medical condition that affects nutrient absorption
- Take medications that deplete certain vitamins or minerals
- You’re pregnant
- Have a health condition that may benefit from supplementation
- Drink large amounts of alcohol.
Not All Supplements Are Bad
Some people can benefit from taking a vitamin D supplement, vitamin K2 (affiliate), magnesium, zinc (after the age of 65) and probiotics. We’ll look at these supplements in greater detail at some point.
Ideally, you’d be able to get enough of each of these vitamins and minerals through diet and, in the case of vitamin D, sun exposure, but it’s not always practical. There is some evidence that people don’t get enough of the minerals and vitamins listed above through diet alone.
There’s also some evidence that other supplements with ingredients you don’t find in a multivitamin may be beneficial for people with certain conditions. For example, alpha-lipoic acid may have benefit for people with diabetic peripheral neuropathy.
The best approach is to talk to your physician and schedule sessions with a dietitian so they can analyze your diet and see if you’re getting all of the vitamins and minerals you need. Don’t automatically take one because of clever marketing or based on someone’s advice who has not medical training. Make sure it’s right for you!
- Harvard T.H. Chan. Nutrition Sources. “Vitamin A”
- Mayo Clinic “Vitamin A”
- Cancer Council NSW. “Folate and Cancer Risk — Position Statement”
- NutritionFacts.org. “Are Multivitamins Just a Waste of Money?”
- JAMA. 2012 Nov 7;308(17):1751–60. doi: 10.1001/jama.2012.14805.
- Live Science. “Are Vitamin E Supplements Healthy or Harmful?”
- Diabetes. 1997 Sep;46 Suppl 2:S62–6.