Can you have too much vitamin D? And, if so, what are the side effects of vitamin D? The detrimental effects of vitamin D deficiency are well known and garnering more and more attention in the medical news. But, like nearly everything else too much of a good thing can be detrimental too, and the same appears true with vitamin D as well. But, it’s hard to get too much vitamin D in my experience. The good news is levels of vitamin D are easy to obtain so there is little risk of getting too much vitamin D if being properly monitored.
A recent study involving 132,000 participants presented at the annual meeting of the American Heart Association showed that higher than normal levels of vitamin D can cause atrial fibrillation, an abnormal heart rhythm. In that study vitamin D levels above 100 ng/dl was considered excessive.
In patients with kidney disease too much vitamin D can raise calcium levels in the blood increasing the risk of hardening of the arteries. Vitamin can also increase calcium in patients with sarcoidosis and histoplasmosis. Deposition of calcium can be prevented or minimize by obtaining adequate amounts of vitamin K2 which keeps calcium in the bone and prevents it from depositing the blood vessels. See our post “Vitamin K: Protect Your Bones and Prevent Cardiovascular Disease“. Individuals taking the blood thinner warfarin should not take vitamin K without consulting with their doctor.
Though vitamin D levels above 30 ng/dl are considered normal, more and more evidence suggests that levels between 50 ng/dl and 70 ng/dl are optimal. And, an increasing number of physicians are recommending levels in this range.
How Much Vitamin D Should I Take?
When recommending vitamin D dosing it’s important to recognize that someone in a bathing suit will make 10,000 units of vitamin D after being exposed to bright sun for 30 minutes. So, there should be little concern with taking more than the 400 IUs to 800 IUs many doctors still recommend. Because vitamin D levels are easy to monitored there’s no reason to guess on the dose. Take as much as you need to get your levels in the optimal range of 50 ng/dl to 70 ng/dl. Many individuals will find that they will need to take 5,000 IUs a day and some even 10,000 IUs a day.
Vitamin D levels will fluctuate and are somewhat seasonal depending on how much sunlight you get. There is little benefit from the sun on vitamin D production between November through February as the sun sits too low in the sky. So you may need to increase your vitamin D dose during those months. In the end, too little vitamin D is far more common and far more detrimental than too much vitamin D.
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