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Overdosing On Vitamin D: Side Effects, Toxicity, Symptoms, Poisoning

Overdosing on Vitamin D: Side Effects, Toxicity, Symptoms, Poisoning

I promised to write one column about the side effects of vitamin A, vitamin B1 (thiamine), vitamin B3 (niacin, niacinamide), vitamin C, and vitamin D (cholecalciferol). Deficiency in these five vitamins causes death and disability from vitamin A deficiency, beri beri, pellagra, scurvy, and rickets respectively. Im going to start with vitamin D because there is an urgent need to understand vitamin D better.

Vitamin D is a hormone. It is not found in food in high levels. It is difficult to obtain 1000 IU/day of vitamin D from food. Agricultural workers and lifeguards will produce 20,000 to 50,0000 IU/day in the skin. Hormones are well understood to be remarkably effective drugs. Powerful hormones such as human growth hormone have been shown to have remarkable beneficial effects. This hormone, however, is rarely used because, it is highly dangerous. Steroids to promote muscle growth are known to be dangerous. Hormones for birth control are known to be dangerous. I think it is safe to say that most hormones are dangerous when taken as a drug. Why would anyone expect vitamin D to be different?

Lots of people who expected to be healthy, and worked hard to live a healthy life, are none the less struggling with their health. These folks have tested the “healthy” lifestyles (low fat, low carbs, vegetarian, vegan, exercise three times/week, meditation, religion) Despite all the testing, I didn’t know what to do. It seemed to me that all the theories were wrong. That’s what I like about the implications of vitamin D. It has led to a theory that I don’t think has been tested. Western life has led us to spend more and more of our time indoors. Indoor life deprives us of sunlight, which causes permanent low levels of two blockbuster hormones vitamin D and melatonin, and cause permanent low levels of at least one other hormone, various neuropeptides, endorphins, and probably some other things I haven’t found yet. Indoor life exposes us to indoor air pollution, and probably is a root cause of other behaviors that are known to be bad for health.

Ive been hesitant to write this column because I don’t want to stop people from taking vitamin D as I believe that vitamin D supplements are doing more good than harm. That said, vitamin D supplements are hormones in a bottle and are obviously dangerous at doses above the upper safe limit of 2000 IU/day set by the Food and Nutrition Board. The other harm the supplements are doing, is sending the message that pills are a safe and effective substitute for sunshine. I’m sure this is true for some people. But what about everyone else? Is the strategy really to use the power of evolution to select for success only children who do the best living in minimal sunlight? Don’t believe in evolution these days? One in 6 couples are outright infertile, and the fertility medicine business is booming. Whether from pills or sunshine, optimizing vitamin D will benefit your health. I believe that sunshine is a better way, but not everyone has the luxury of getting regular sunshine, and not everyone needs regular sunshine. Everyone, however, needs vitamin D.

Vitamin D is is acutely toxic in overdose. A single dose, sufficiently large, is lethal. This dose is determined by scientists by feeding dogs and rats. The data from the dogs and rats indicates that a single dose of vitamin D above 150,000,000 IU (150 million IU) is lethal. It is virtually impossible for a consumer to take a dose like this. In fact, vitamin D is so safe that it is sold in bottles without childproof caps. In the past, I purchased large bottles of 1000 IU vitamin D tablets that contain 300 tablets. If I swallowed the entire bottle, Id be taking 300,000 IU of vitamin D. Id have to swallow 50 entire bottles at once to reach the lethal dose.

That said, vitamin D is impressively toxic. 1000 mg (a standard dosage for a single vitamin C pill) is a lethal dose for the average person. 1000 mg is 40,000,000 (forty million) IU. The fifty bottles of 1000 IU vitamin D pills mentioned above would weigh in the ballpark of 2500 g. A typical vitamin D tablet weighs 150 mg and is >99.9% filling. This makes safely handling vitamin D challenging. All human processes are subject to error. Some 1000 IU pills will occasionally be formulated with >10,000 IU of vitamin D. The unluckly consumer taking poorly manufactured vitamin D supplements can experience “unexplainable” side effects since everyone usually will assume that the consumer is ingesting the dose listed on the bottle label.

Again, vitamin D is impressively toxic. So much so that scientists specializing in mammalian pest control turned to vitamin D as a safe and effective poison. Just type “vitamin D rat poison” into google and you’ll see that you can purchase a rat poison that uses vitamin D as the active ingredient. The poisonous food (the “bait”) is typically close to 1 part in 1 thousand vitamin D. Truth can truly be stranger than fiction. While vitamin D3 advocates are writing that vitamin D3 is non-toxic, exterminators are advertising vitamin D3 as a safe and effective poison for killing mice and rats! What makes it so strange is that vitamin D is surprisingly non-toxic while at the same time being an effective rat and mouse poison. It is, in fact, absurdly non-toxic for an acute poison! Honestly, I’m left speechless.

From a practical perspective, death from taking large doses of vitamin D is not a concern (unless you are a mouse or rat and the exterminator is after you!). The practical concern is toxicity caused by ordinary doses of vitamin D, taken regularly. Ordinary doses can build up in the body over time and cause serious illness. The most serious concern is a small increase in the risk of heart attack and stroke amongst the elderly. This concern was raised a long time ago without much evidence to support it. The evidence is reviewed in a book called “The Right Dose, How to Take Vitamins and Minerals Safely.” I felt the data was insufficient to warrant inclusion in this blog post. Now, new independent data reaches similar conclusions using a completely different line of reasoning. The older data directly associated the risk of heart attack with vitamin D dosage. The new data associates the risk of stroke with vitamin D dosage. Vitamin D should be expected to act systemically on veins and arteries so it makes sense that if vitamin D increases the risk of heart attacks it also would increase the risk of stroke.

This allegation sounds serious, and it is. However, the reported elevated risks remain associated with high doses of vitamin D from food (1000 IU and less have no association with these problems) and are small increases in risk. Cavities, osteoporosis, repetitive motion pains, and other joint and ligament pains are epidemic amongst the elderly. The hypothesis that these problems can be prevented by sun exposure has never been tested (and never will since a double-blind trial of sunshine is impossible). That remains the second point there is no evidence of any association between sunshine, stroke, and heart attack. There is a clear message: get vitamin D from sunshine. Sunlight is also known to alleviate/eliminate allergies, to cause special cells in the skin to produce the alpha melanocyte stimulating hormone (so sunshine has been proven by science to cause the produce of at least three hormones!), to cause the production of a couple of neuropeptides, and to cause the release of endorphins. So while you’re in the sun getting vitamin D, you’ll also be producing a variety of other regulatory chemicals essential for optimal health.

I’ll give my view again here a different way. Most people will obtain far more benefits from 0-4000 IU/day of vitamin D from food/supplements than harm. That said, the risks are well documented. There are no well documented cases of vitamin D side effects caused by sunshine producing too much vitamin D in the skin. There are plenty of known risks from overdoses of sunshine. Acute sun overexposure has been practiced as a form of execution.

Back to the well documented side effects. Not surprisingly, the Mayo Clinic is an excellent source I’ve found on-line for vitamin D side effects. Here is their list:


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