Bathing in Sunshine: The Paradoxical Overdose of Vitamin D

Intense Sunshine Illustration

Overdosing on vitamin D supplements can cause serious health problems, including hypercalcemia and kidney damage. It’s essential to maintain a balance and avoid excessive intake to prevent toxicity. Credit:

Vitamin D, colloquially known as the “Sunshine Vitamin,” is renowned for its crucial role in maintaining optimal health. Our bodies naturally produce vitamin D when our skin is exposed to sunlight. It is also available through diet and supplementation. The sunshine vitamin assists in various physiological processes, including calcium absorption for healthy bones and teeth, as well as immune system support. However, what happens when we ‘overdose’ on this vital nutrient? Can you indeed have too much of a good thing?

The concept of getting too much vitamin D might seem bizarre. After all, reports of vitamin D deficiency far outstrip cases of its excess. Still, vitamin D toxicity, or hypervitaminosis D, is a genuine, albeit rare, condition that poses significant health risks. It is primarily caused by excessive consumption of vitamin D supplements, and not by diet or sun exposure.

Food Containing Vitamin D

Food sources of vitamin D include oily fish, including salmon, mackerel, and sardines, as well as egg yolks and fortified milk.

The Culprit Behind Vitamin D Overdose

Sunbathing and food sources, contrary to popular belief, are not typically responsible for vitamin D toxicity. The body has an inbuilt mechanism to prevent the overproduction of vitamin D from sunlight. Similarly, it’s almost impossible to consume too much vitamin D through food alone, as very few foods naturally contain it.

Vitamin D supplements, on the other hand, can cause levels to skyrocket if taken in excess. In the U.S., the daily recommended dietary allowance for adults is between 600 and 800 international units (IU) of vitamin D. Toxicity is generally observed when taking 10,000 to 60,000 IU/day for a few months or longer, or as a single very large dose.

Vitamin D Recommended Daily Intake*

Life StageRecommended Amount
Birth to 12 months10 mcg (400 IU)
Children 1–13 years15 mcg (600 IU)
Teens 14–18 years15 mcg (600 IU)
Adults 19–70 years15 mcg (600 IU)
Adults 71 years and older20 mcg (800 IU)
Pregnant and breastfeeding teens and women15 mcg (600 IU)

The Unseen Impact of Vitamin D Overdose

The primary consequence of vitamin D toxicity is a buildup of calcium in your blood (hypercalcemia), which can cause nausea, vomiting, weakness, and frequent urination. Symptoms might progress to bone pain and kidney problems, such as the formation of calcium stones.

Moreover, consistently high levels of vitamin D can lead to heart problems, such as irregular heartbeat and hypertension. It can also damage the kidneys and, in severe cases, cause kidney failure. Elevated calcium levels due to long-term vitamin D toxicity can result in vascular and tissue calcification, leading to heart attack and stroke.

Man Hospitalized After Losing 28 Pounds From ‘Overdosing’ on Vitamin D Supplements

Last year, doctors warned in the journal BMJ Case Reports that ‘overdosing’ on vitamin D supplements is both possible and harmful after they treated a man who needed hospital admission for his excessive vitamin D intake. The patient, a middle-aged man, began having problems about a month after he began an intensive vitamin supplement regimen on the advice of a nutritional therapist. His symptoms included recurrent vomiting, nausea, leg cramps, abdominal pain, increased thirst, dry mouth, tinnitus, diarrhea, and weight loss.

Prevention is Better than Cure

While vitamin D toxicity is rare, its implications are severe enough to warrant caution. If you’re taking a vitamin D supplement, make sure it does not exceed the recommended daily allowance unless instructed by a healthcare provider. Regular testing of vitamin D levels, especially for those on high-dose supplements, can prevent inadvertent toxicity.

The balance, as always, is key. While ensuring sufficient vitamin D levels is crucial for bone health and immune function, going overboard can have undesired consequences. The sunshine vitamin, like all good things, is best enjoyed in moderation.

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*These are the average daily recommended amounts according to the U.S. National Institutes of Health (NIH) Office of Dietary Supplements (ODS).

10 Comments on "Bathing in Sunshine: The Paradoxical Overdose of Vitamin D"

  1. Please consult your doctor. Diets vary per country and so does vitamin D recommendation. Also, many breast feed substitutes contain added vitamin D.

  2. Truth betold | May 21, 2023 at 2:41 pm | Reply

    Daily rda are nonsense and far to low taking vit d under 1000iu will do absolutely nothing to help you if your levels are low the healthy ranges are also nonsense 20ng is considered the low end of normal but that level is attrocias this article does absolutely nothing but scaremong about vit d toxicity and provides no real value and does more harm than good there’s so much more nuance such as taking supporting vitamins like k2 to transport the extra calcium to your bones and teeth and magnesium because vitd depletes magnesium most people would benefit from taking a good dose of vitamin d with mag and k2 and getting to a healthy level I took 200,000 week with k2 and mag with dinner for 5 months and my vitd levels went to 99ng which is quite high but my calcium levels are normal right in mid range not elevated at all of if I can take 30k to 50k 4/5 times a week for 5 months and get to 99 ngram and be perfectly healthy with normal calcium levels with no side effects apart from sleeping the best I’ve ever slept mentally the best I’ve ever felt and avoiding all my family’s colds then taking 10k a week with mag and vit d should be perfectly safe for pretty much anyone except those with rare conditions related to vitamin d the rda will not raise your levels at all and are designed to keep you sick studied vitamin d from top vot d scientists for years you should really do your homework instead of scaring people away from one of the most important and beneficial vitamin / hormones out there

  3. This was written by someone with an agenda or someone who has no idea what the term “risk/benefit ratio” means. You have to be an unhinged person to take that many supplements to hurt yourself with vitamin D.We prescribe 50,000 IUs per week when treating deficiencies (below 15) for six weeks. This is scaremongering of the worst kind–the kind that can hurt people.

  4. I am a ARNP who took 5000 units a day for many years . Over that time I saw my Renal functions deteriorate . I was in type 3 B Renal failure with my GFR and creatinine levels deteriorating. I ran out of 5000 U meds on an extended visit so took 1000 U for 60 days . My next Renal functions were WNL . it was the only change I made and my Renal functions have been normal ever since the point being every patient is different and my experience confirms large codes are not without risk .

  5. Vitamin D is FAT soluble,meaning it will build up in your fat,making it very capable to overdose on,most useusdoctors provide a dose ONCE weekly,too much Vitamin D can cause severe bodily harm,but it is essential for proper brain function (preventing dementia).

  6. Not sure what’s worse. The article, or these comments.

  7. There are various types of vitamin D. The sun is its own type versus food types. If you’re going to use AI to write your articles at least fact check before publishing.

  8. Where’s the evidence for this assertion? Here’s a great (longitudinal) study that’s peer reviewed showing the claims in this article to be unfounded:

    The Journal of Steroid Biochemistry and Molecular Biology
    Volume 189, May 2019, Pages 228-239

    Daily oral dosing of vitamin D3 using 5000 TO 50,000 international units a day in long-term hospitalized patients: Insights from a seven year experience.

  9. This was written by someone who did not do there research and background checked right. Have a look in the scientific publications and you find decent research as well how to calculate the right dodes to be used as well the supplement support needed of K2-mk7, Q10, magnesium, sink.

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