Going Overboard with D: How much Vitamin D should you take?

Are people overdosing on vitamin D? Is it even possible to take too much vitamin D? Do you even need to take any vitamin D? If so, how much vitamin D should you take?  A recent article in Journal of the American Medical Association suggested that many people are now taking doses which may be too much vitamin D. So how does one know what to do about Vitamin D?

There is great evidence to prove Vitamin D’s important role in bone health, calcium absorption and osteoporosis treatment. It is also likely to a play a role in migraine prevention, energy, muscle aches and even immunity, depression, blood sugar control and weight loss. If it is so wonderful for so many things, you may ask, why aren’t we all taking as much as we can?

Well, it turns out that, as with many things in life, too much of a good thing is not always better. In fact, too much Vitamin D is down right harmful.  Excessive doses of Vitamin D can cause kidney stones, high blood calcium levels, which can lead to constipation, slowed thinking, even coma and more.

So are people really overdoing the vitamin D? Turns out, many are. The recent JAMA study looked at people’s habits and found that from 1999-2000 less than .1% of people reported taking 4000 IU or more of vitamin D daily.  But in the recent survey in 2013-2014 3.2 % reported taking that much. This is an increase in the number of potential overdoses by over 30 times. 

The study is both good news and bad news. It tells us that many more Americans are aware of the importance of vitamin D. In our personal experience, the majority of Americans are deficient in this important hormone if they are not taking a supplement (this is true to varying degrees depending on factors such as age, where you live, ethnicity, diet and more). You can read more on sources of D here. After decades of seeing patients measuring their blood levels of Vitamin D ( a practice which is both costly and not always necessary) we have concluded that the majority of people do well on between 800 and 1200 IU daily of Vitamin D3 (the more active metabolite of D).  Of note, this is more than the US daily recommended allowance of 400 or 800 Its depending on age. The truth is, that amount can rarely get most people to an optimal blood level. 

That being said, taking more than 4000, or even 2000 IU daily is rarely necessary. Yes, there are occasions when higher doses are needed—typically those who are profoundly deficient (levels under 15 ) or those who do not absorb D adequately because of having had intestinal surgeries, Crohn’s disease, colitis or celiac.  The vast majority of people will get to a normal and healthy vitamin D level with a moderate amount of D (800-2000 IU daily) if they take a regular daily dose and stick with it year round. Many people are under the false notion that they should only take Vitamin D during winter months when sunlight is limited (our main source of D). The reality is vitamin D is a fat soluble vitamin, meaning that it takes time to fill up your body stores (and likely more time, the more body fat you have). We do not routinely recheck vitamin D levels when replacing for at least 6 months since it typically takes that long (or sometimes even years) to build up to a normal level.  That being said once levels get to an optimal range— in our opinion between 40 and 50 (though this has been much debated). One needs to stay on a daily dose of D, typically between 800 and 1000 IUs.

So back to this whole notion of taking too much. Is it really going to hurt you to take too much vitamin D? Many would suggest yes. One large study showed that vitamin D levels and mortality follow a U shaped curve. Those at the low end and the high end of the range have higher mortality.  This pretty much solidifies the too much of a good thing theory.   

So what is the take away? Many Americans are on to the fact that vitamin D is a necessary and important addition to their daily regimens. Not all are, and many still suffer from deficiency, whether they know it or not. Of those taking vitamin D, it is very important — as with all vitamins) to take a proper amount, based on your individual needs. Just because my friend or neighbor takes 800 IU daily does not by any means imply that I need the same amount. We should all take a custom vitamin regimen (take our personalized vitamin quiz) based on our own individual diet, lifestyles and health concerns.


Romy Block specializes in Endocrinology and Metabolism and is mother to three active adolescent boys. Arielle Levitan is a Doctor of Internal Medicine with a special interest in Preventive Medicine and Women’s Health.  She is a mother of three teen agers. As professional women with active family lives, they recognize that people often neglect their own health needs and are uncertain about what vitamins to take. Each person is different in her diet, exercise and health history, and will benefit from different nutrients.  After years of advising their patients about the proper vitamins to take,  Drs. Block and Levitan created Vous Vitamin® to provide people everywhere with quality vitamins that are suited to their individual needs. They are authors of the award winning The Vitamin Solution: Two Doctors Clear Confusion About Vitamins and Your Health (She Writes Press, 2015). Take your vitamin survey now to get exactly the right vitamins for your needs.

The statements made in this article have not been evaluated by the Food and Drug Administration. The products offered by Vous Vitamin® are not intended to diagnose, treat, cure, or prevent any disease.

Nothing contained herein is intended to be a diagnosis or constitute medical advice.  The symptoms described in this Blog may be a result of a serious medical condition which requires medical treatment.  You should consult with your doctor if you are experiencing any of the symptoms mentioned in this Blog and before beginning any vitamin or supplement regimen.

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