Rustsmith wrote:Vitamin D may be yet another factor that needs to be added to the blood analysis list of WED patients. A few years ago my neurologist checked my Vit D levels based upon issues I was having with a medication I was taking. Turned out I was low, so she recommended 2000 units/day. Six months later my GP checked as part of his standard suite of blood checks for "older" patients. Turned out I was high enough that he recommended dropping back to 1000 units/day. In many ways, Vit D is like iron, too little and it is a problem. But too much of a good thing can also be a problem.
From what I've read, it's really hard to get too much. Even at 10,000 IUs a day, it seems likely to be safe.
From WEB MD: "But some recent studies suggest that healthy adults can tolerate more than 10,000 IU of vitamin D per day. John Jacob Cannell, MD, executive director of The Vitamin D Council, notes that the skin makes 10,000 IU of vitamin D after 30 minutes of full-body sun exposure. He suggests that 10,000 IU of vitamin D is not toxic."
From Mayo Clinic: "Taking 50,000 international units (IU) a day of vitamin D for several months has been shown to cause toxicity. This level is many times higher than the Recommended Dietary Allowance (RDA) for most adults of 600 IU of vitamin D a day."
From Cleveland Clinic: " Vitamin D blood levels exceeding 100 ng/mL can be dangerous. The extra vitamin D triggers extra calcium absorption. This can cause muscle pain, mood disorders, abdominal pain and kidney stones. It may also increase risk for heart attack and stroke.
“Most reports of toxicity involve patients taking synthetic vitamin D2, so we prescribe natural vitamin D3,” says Dr. Young."
And, from the Vitamin D Council:
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Am I getting too much vitamin D?
"Although most people take vitamin D supplements without any problems, it’s possible to take too much. This is called vitamin D toxicity. Vitamin D toxicity, where vitamin D can be harmful, usually happens if you take 40,000 IU per day for a couple of months or longer, or take a very large one-time dose.
Vitamin D is fat-soluble, which means your body has a hard time getting rid of it if you take too much. When you take large amounts of vitamin D, your liver produces too much of a chemical called 25(OH)D.
When your 25(OH)D levels are too high, this can cause high levels of calcium to develop in your blood. High blood calcium is a condition called hypercalcemia.
The symptoms of hypercalcemia include:
feeling sick or being sick
poor appetite or loss of appetite
feeling very thirsty
passing urine often
constipation or diarrhea
muscle weakness or pain
In some rare diseases, you may be at risk of hypercalcemia even if you have low vitamin D levels and haven’t taken much vitamin D. These diseases include primary hyperparathyroidism, sarcoidosis and a few other rare diseases. See our Hypersensitivity page page for more information."
"Very high levels of 25(OH)D can develop if you:
1. take more than 10,000 IU/day (but not equal to) everyday for 3 months or more. However, vitamin D toxicity is more likely to develop if you take 40,000 IU/day everyday for 3 months or more.
2. take more than 300,000 IU in a 24 hour period."