…especially when it comes to vitamin D.
As a registered dietitian, my goal is to educate on how to nourish your body properly so you can feel your best and maintain good health over time. Lately, when I head to my local market or Whole Foods, I find folks are loading their carts with vitamins and mineral supplements.
Supplements have been around since the 1940’s, and according to the National Institute of Health, an estimated one-third of Americans takes one kind or another. The problem is that when a report comes out that says “Americans are deficient” in a certain nutrient or someone recommends a specific vitamin on the evening news, health-conscious people go running to that supplement aisle where many think that more is better.
Vitamin D is a perfect case in point. A recent research letter published in the Journal of the American Medical Association found the percentage of adults in the U.S. taking 1,000 International Unites (IU) or more of vitamin D increased from 0.3 percent to 18.2 percent from 1999 to 2000 and 2013 to 2014, respectively. That’s a whopping increase of more than 60 times. The recommended daily allowance for vitamin D is 600 IU per day for adults up to 70 years of age and 800 IU per day for those over 70 years of age. The maximum amount before potentially seeing signs of toxicity is 4,000 IU per day.
The increase in vitamin D supplementation came when published studies found that most Americans were not getting enough. The vitamin is not widely available in food (egg yolks, fish liver oils, and fortified milk are main sources) so now at your annual check-up your blood workup includes vitamin D levels. Many physicians now recommend supplementation when levels are found to be low, which is completely healthy and fine, but many Americans also take matters to their own hands without talking to a doctor, which can be dangerous. Taking excessive amounts over the tolerable upper limit can result in hypercalcemia (high levels of calcium, which can adversely affect your kidneys, digestive system, brain, and heart) and calcification of soft tissue and blood vessels, which can similarly disrupt organ function.
But it's not just vitamin D. You can get toxicity effects from numerous vitamins and minerals taken in excess including vitamin A, B-vitamins, and calcium. Too much vitamin A can result in hair loss, bone pain and damage, skin problems, and liver damage. Over-consuming vitamin B6 can lead to irreversible nerve damage, while too much calcium can lead to the development of calcium deposits in the kidneys and other organs.
The bottom line: Popping a multivitamin or supplement won’t correct an unhealthy diet and you should only be taking one if you verified that your body needs it. First, see your physician and/or registered dietitian to see if you're deficient. My philosophy is food first: If you're eating a well-balanced diet you should be in the clear. Consult an R.D., who can analyze your daily meal plan to see how much you’re getting from food, help you make any changes to get the necessary nutrients from your diet, and if necessary recommend the proper dosage from supplementation.
Toby Amidor is a registered dietician and adjunct professor at Teachers College, Columbia University in New York City, and author ofThe Greek Yogurt Kitchen.