People Are Taking Too Much Vitamin D: Here's Why That's Bad


You’ve probably heard at some point that Americans aren’t getting enough vitamin D, the so-called sunshine vitamin that helps promote healthy bones. So naturally, it makes sense that people would start taking vitamin D supplements.

A new study shows that some people are taking way too much vitamin D. (Photo: Getty Images)
A new study shows that some people are taking way too much vitamin D. (Photo: Getty Images)

Unfortunately, new research has found that a significant number of people are taking daily vitamin D supplements above the recommended levels, and some are even taking them at levels that could pose a danger to their health.

Vitamin D is important for bone health, but can cause abnormally high levels of calcium in the blood, soft tissue, or blood vessels if taken above the upper limit of 4,000 IU a day. Currently, the recommended dietary allowance for vitamin D is 600 IU daily for adults under the age of 70 and 800 IU for those over 70.

In the June 20 study, which was published in JAMA, researchers analyzed data from 39,243 people who participated in the nationally representative National Health and Nutrition Examination Survey and looked at the trends of those who had a daily supplemental vitamin D intake of 1,000 IU or more, as well as those to took 4,000 IU or more, from 1999 through 2014.

The study’s researchers found that more than 18 percent of people studied took 1,000 IU or more of vitamin D from 2013 to 2014, which is a dramatic uptick from the 0.3 percent who did the same thing between 1999 and 2000. Not only that, 3.2 percent of people studied took 4,000 IU or more of vitamin D a day between 2013 and 2014, which puts them at serious risk of health problems.

In general, women, non-Hispanic white people, and people over the age of 70 were more likely to take more than 4,000 IU of vitamin D.

Women’s health expert Jennifer Wider, MD, tells Yahoo Beauty that vitamin D is important for the absorption of calcium. “It plays a role in maintaining healthy bones and teeth, [but] it has other roles including supporting the immune system, brain, and central nervous system,” she says. “It also helps regulate insulin and plays a role in the gene expression in the development of some cancers.”

And without vitamin D, a person’s bones can become thin or brittle, Gina Keatley, a certified dietitian nutritionist practicing in New York City, tells Yahoo Beauty.

But people typically get vitamin D from sunlight, and their levels of the vitamin can vary depending on the time of year and even time of day, Keatley points out. Vitamin D supplements might be necessary for people who have low levels of the vitamin since it’s necessary for the absorption of calcium, Wider points out. But it’s also possible to have too much vitamin D, which can cause a range of issues including nausea, vomiting, muscle weakness, and kidney problems. At very high levels, it can even lead to heart attacks. Luckily, Keatley says, vitamin D toxicity is “extremely rare,” though it can happen.

That’s why Wider recommends talking to your doctor before starting vitamin D supplementation and making sure you discuss dosing as well. Again, it’s recommended that most people get 600 IU of vitamin D, and there’s really no reason to go over that unless your doctor advises it.

You can also try a few things before you start a supplement routine. If you’re vitamin D deficient, Keatley says you can increase your intake to recommended levels through vitamin D-rich foods such as egg yolks, saltwater fish, and liver. Research has also shown the levels of vitamin D increase when people are at an ideal weight compared with overweight, so living a healthy lifestyle is important too. And, Keatley adds, it doesn’t hurt to “get a little bit of sun” — about 15 minutes per day.

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