Are concerns about vitamin D toxicity valid? This article examines this issue and provides you with information you may need to know....
by M. Daniels, who has been professionally writing and editing technical non-fiction articles and publications for over 3 decades.
To put this issue in perspective the comments
of a doctor who has specialized in studying this vitamin may be of
interest: Dr. John Cannell concluded:
"worrying about vitamin D toxicity is like dying of thirst in the desert while worrying about drowning." from [The Truth About Vitamin D Toxicity]
In fact, there are several symptoms which may be early signs of a vitamin D overdose, or simply a side effect for people who are intolerant to supplements. Those that have been identified are:
If you experience these symptoms together and/or repeatedly they may result from vitamin D toxicity. The prudent thing to do would be to suspend using Vitamin D or calcium supplements, stay out of sunlight and consult your doctor and tell him that you have been taking Vitamin D and how much.
Government agencies have established what they call the 'Tolerable Upper Limit' (TUL) dosage for vitamin d supplements, (It may also be named 'safe upper limit'). This is in their view the maximum amount which healthy people can use for long periods of time without experiencing any undesirable effects.
As of February, 2011 the US Office of Dietary
Supplements states the Vitamin D TUL for all people over 9 years old is
4000 IU (100mcg) daily,
however, there is no unanimous agreement that this is valid. Many
experts have amassed a large amount of research about However
there has been research into Vitamin D which leads these specialists to
argue that this maximum limit should actually be the Recommended Daily
Allowance (RDA) instead.
An article called "The Pharmacology of
Vitamin D, Including Fortification Strategies" reports that
" ... despite 70 years of experience with the use of super-physiological amounts of vitamin D, there has never been a report of a sudden excess of vitamin D ...", that "Toxicity in normal adults requires intake of more than 1000 mcg/day (40,000 IU/day), which reflects amounts of vitamin D that are four times more than the 250 mcg/day can be acquired naturally by sunshine" and, perhaps most importantly that "If a consumer wanted to achieve [a] toxic dose, he or she would need to take forty of the 1000 unit pills (the highest dose available in North America without a prescription) every day for many months".
In another study reported in the American Journal of Clinical
Nutrition, reported that review by that journal using the same methods
which the Food and Nutrition Board uses to assess risk concluted:
"that the UL (safe upper limit) for vitamin D consumption by adults should be 10,000 IU per day" and this implies that adults could comsum more than 10 times the amount which was currently recommended without any risk.
There is a further study of pregnant women were given 100,000 International Units (IUs) per day (ten times the TUL) for their entire pregnancy and this lead to the conclustion that "... there is no evidence in humans that even a 100,000 IU/d dose of vitamin D for extended periods during pregnancy results in any harmful effects."
Since we manufacture our own vitamin D from sunshine it is important to note that there have been no reports of Vitamin D toxicity from too much sunshine.
The body automatically prevents too much Vitamin D from being made
through the skin. As the skin gets darker through tanning,
vitamin D production stops. Of course there are other reasons to limit
your exposure to the sun, but getting too much vitamin D is not one.
If there is any likelyhood of overdosing is is most likely to come
from overusing supplements far in excess of recommended limits.
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