Vitamin D: Too Much of a Good Thing

The number of people taking vitamin D supplements above the recommended levels has increased, according to a new study. But taking too much vitamin D could be unhealthy.

That's because exceeding recommended daily vitamin D limits could lead to problems like abnormal levels of calcium in the blood and calcium buildup in the arteries and soft tissues.

At normal levels, vitamin D is healthy and beneficial, the researchers behind this study noted. It's known for improving the health of bones. 

But this study, which looked at national health data between 1999 and 2014, found that 3 percent of people who took vitamin D supplements were exceeding the daily upper limit. The tolerable upper limit of vitamin D is 4000 IU a day.

These researchers noted that the recommended daily allowance of vitamin D is around 600 IU for adults 70 years old and younger and 800 IU for those older than 70.

Around 18 percent of the 39,243 participants in this study were taking 1,000 IU or more daily in the final year of this study. At the start of the study, only 0.3 percent of participants were taking that much vitamin D.

In the final year of this study, around 3 percent of the participants were taking 4,000 IU or more daily.

Never start or stop taking a medication or supplement without the approval of your health care provider. If you're concerned about your vitamin D intake, speak with a health care professional.

This study was published in JAMA.

Information on study funding sources and potential conflicts of interest was not available at the time of publication.