If you're taking vitamin D, you're probably taking too much

Vitamins seem like something you can’t have too much of. Like too much ice cream on a sticky summer day—sure, you can technically go overboard, but the limit is so high, and what’s the worst thing that happens anyway? And unlike ice cream, we know that vitamins help keep us healthy.

But just like ice cream, vitamin D can have negative side effects when taken in large doses, the impacts can really sneak up on you, and obesity is a concern. Really.

The tricky thing about “medicines” like vitamin D is that you don’t immediately overdose on them. If you take too much Tylenol, you end up in the hospital pretty fast. That giant vitamin capsule isn’t likely to land you in the ER tomorrow or even a month from now. But vitamin D, unlike many of the other vitamins you may be taking, is fat soluble. That means that if you take too much of it, you won’t just pee it out like you would a water soluble vitamin. Instead of being carried out in your body's wastewater, the vitamin will cling to your body fat for later use—which can compound the effects of daily overdosing. But it's easy to think of supplements as harmless when you're just popping a pill or two in your bathroom each morning.

More and more people are making that mistake. In fact, two vitamin D capsules a day (at 2000 international units each) adds up to 4000 IU—the daily limit. If you’re taking in any vitamin D at all otherwise (and you almost certainly are), you’re already over the safe dosage. And a new study in the Journal of the American Medical Association suggests that 3.2 percent of all Americans are doing just that. If 3.2 sounds tiny to you, keep in mind that back in 2007-2008 that number was only 0.2 percent.

The increase in vitamin D overdosing is a symptom of the general trend towards taking more vitamin D supplements. About 18 percent of U.S. adults are taking at least 1000 IU a day, which is well above the recommended daily dose of 600 IU. The question is: is that a problem?

Read more at: https://www.popsci.com/too-much-vitamin-d