Oral Vitamin D: How Much Is Too Much?
This Depends on How Much Vitamin D You Already Have in the Blood, but 4000IU (100mcg) or More per Day Is Likely to Be Dangerous
Vitamin D is crucial to the health of the body and the skin. But does it play a role in acne? We don't know exactly, but limited research shows us that people with severe acne may have lower levels of vitamin D in the blood than people without acne. Vitamin D is known to reduce inflammation, keep bacteria in check, and promote wound healing as well, all of which are important when it comes to acne. Regardless of whether achieving adequate vitamin D levels helps with acne, it is important for overall health.
A healthy amount of vitamin D in the blood is 30 - 50ng/mL, and only people whose vitamin D levels fall below this range should take supplements. The amount of supplement will depend on how much vitamin D is already in the blood, but doctors consider 4000IU (100mcg) or more per day to be dangerous. Because vitamin D is fat-soluble, it can accumulate in the fat cells of the body to toxic levels. Taking too much vitamin D can cause serious side effects, such as weak bones, kidney stones, and problems with heart and brain function.
Note: Only people who have tested positive for vitamin D deficiency should take vitamin D supplements, so if you think you might be vitamin D deficient, ask your doctor for a simple blood test to check your levels.
- Vitamin D and Acne
- Where Do We Get Vitamin D?
- How Much Vitamin D Should We Have in the Blood?
- In Summary
Vitamin D and Acne
Vitamin D is an important nutrient that helps our bodies fight infections and reduce inflammation (the redness, swelling, and pain that result from infections and diseases). In addition, vitamin D plays a crucial role in wound healing.1,2
Both inflammation and wound healing are important parts of acne. Inflammation is one of the first steps in the development of acne lesions, and is present throughout an acne lesion's life cycle. And acne lesions themselves are a type of wound. This means that vitamin D can probably help to improve acne, since it can reduce inflammation as well as help acne lesions to heal more quickly.
Vitamin D also possesses antimicrobial (antibacterial) effects, which may make it useful in the treatment of acne since acne involves a strain of bacteria called Propionibacterium acnes (P. acnes).
Indeed, research has already shown that vitamin D can help in treating other skin conditions, such as psoriasis and atopic dermatitis.1,3 However, we currently only have a small amount of indirect evidence that vitamin D helps with acne.
A study published in the journal Dermato-Endocrinology in 2014 looked at the amount of vitamin D in the blood of people with nodulocystic (severe) acne compared to people without acne. The researchers found that people with nodulocystic acne had lower levels of vitamin D in their blood. The authors of the study wrote, "The patients with nodulocystic acne had relatively low [blood] vitamin D levels compared with the subjects in the control group."3
This finding suggests that having less vitamin D in the blood makes a person more likely to develop severe acne. However, we need to keep two considerations in mind. First, the study was small, with less than 100 total participants, which means that we cannot draw any conclusions until a larger study confirms the finding. Secondly, the study does not show a cause-and-effect relationship: in other words, it does not actually demonstrate that if a healthy person becomes vitamin D - deficient, he or she will develop severe acne. Therefore, we must exercise caution when examining the results of this study.
It may be prudent for anyone with acne, and especially those with severe acne, to ask their doctor to order a blood test to see if they are deficient in vitamin D. The test for vitamin D deficiency is an easy blood test, and anyone can ask for one. Doctors consider a blood vitamin D level of 30 - 50ng/mL to be healthy. If the test shows that the level of vitamin D is below this range, a doctor may recommend supplements. It is important to follow the doctor's instructions and not to exceed the recommended amount of supplement, since vitamin D overdose can be dangerous. For daily supplements, a dose of 4000IU (100mcg) or more per day may be toxic.
Where Do We Get Vitamin D?
Our skin normally produces most of the vitamin D present in our bodies. Whenever the sun shines on the skin, the skin synthesizes vitamin D from the cholesterol in our bodies. To occur, this reaction needs the sun, so people who show low levels of vitamin D probably do not get enough sun exposure. Our ancestors easily got all the vitamin D they needed from sun exposure. However, in today's world, we get far less direct sun exposure.
Not having enough vitamin D causes problems because it is essential for many parts of the body to function. The immune system needs it to work properly and fight infections; the bones need it to absorb calcium and form or repair properly, and the muscles need it to function. Thus, people deficient in vitamin D can experience symptoms such as fragile bones, hair loss, fatigue, muscle pain, and become sick often.
How much sun exposure we need to make enough vitamin D depends on several factors.
- Skin pigmentation: The darker the skin, the more time in the sun we need to make enough vitamin D. Because each individual has a unique skin tone, each person needs a different amount of time in the sun to produce enough vitamin D.
A 2006 article in the Bulletin of the World Health Organization gave this example: "With the amount of sun that would require 10 - 12 minutes of exposure in a fair skinned person to achieve maximum vitamin D levels, it may take three times longer for an Asian Indian and up to ten times as long in a deeply pigmented African American."4
- Amount of exposed skin: The more skin that is exposed, the less time in the sun we need for adequate vitamin D levels.4 The amount of exposed skin depends on individual clothing preferences and on weather conditions. One of the reasons that people need more time outside in the winter is that winter clothing usually covers most of the skin.
- Intensity of ultraviolet (UV) rays: The more intense the UV rays, the less time in the sun we need to make enough vitamin D. The intensity of UV rays changes depending on the geographical location and the season. Therefore, the same person may need only a few minutes of sunlight in the summer, but several hours in the winter.4,5
- Sunscreen: Sunscreen absorbs, reflects, and/or scatters UV rays before they reach the skin, which prevents the skin from using UV rays to make vitamin D.
Each of these factors can vary significantly from person to person, so it is difficult to give general recommendations for how much sun exposure the average person needs to have enough vitamin D. In general, people with the lightest skin need about 20 minutes of unprotected sun exposure per day on large areas of the body, and people with darkest skin need 2 hours or more.
When we talk about how much vitamin D is too much, we are talking only about the vitamin D that a person gets from food or from supplements. This is because the body self-regulates the production of vitamin D from sun exposure. As soon as the body has made enough vitamin D from the sun it will stop.
However, it's a different story when it comes to supplements. Since vitamin D is fat-soluble, the body stores any unused amounts of the vitamin in fat cells. This means that if a person keeps taking supplements, the body will keep building up its stores of vitamin D to potentially toxic levels.
We can obtain some vitamin D from natural food sources by maintaining a healthy and varied diet. Vitamin D is mostly found in animal products, such as meat, fish, and eggs. Additionally, manufacturers can add vitamin D to some products, such as milk, orange juice, or cereal, to make them vitamin D - fortified.6
Vitamin D supplements
If your doctor tests your blood for vitamin D and finds that you have a vitamin D deficiency, he will probably recommend a supplement. Doctors normally do not recommend sunbathing to increase vitamin D, since it is difficult to determine how much sun exposure a particular person will need, and since too much time in the sun poses other health risks.
When it comes to supplements, some people take cod liver oil or fish oil capsules, since these contain high concentrations of vitamin D. However, most people take vitamin D supplements, which there are two types of.
- Vitamin D3 supplements: Most over-the-counter vitamin D, such as in multivitamins, is of this kind. Vitamin D3 is the type of vitamin D that our bodies make and that food sources normally contain. It is also more bioactive, which means it is more powerful inside the body.
- Vitamin D2 supplements: Most prescription vitamin D supplements are of this kind. Vitamin D2 is made by mushrooms and fungi, as well as in commercial labs. It is the slightly less bioactive type of vitamin D.6
How Much Vitamin D Should We Have in the Blood?
Doctors measure the concentration of vitamin D in the blood in ng/mL (nanograms per milliliter) or in nmol/L (nanomoles per liter). No matter how much time you spend in the sun, your skin will only make enough vitamin D to reach a blood level of, at most, 80ng/mL. When your body approaches this level, it stops the production of vitamin D in the skin so that the amount of vitamin D does not reach dangerous levels. In other words, you will not experience vitamin D toxicity just by staying out in the sun too long.
Unlike water-soluble vitamins, which get flushed out of the body on a daily basis, vitamin D can build up in the body over a long period of time since the body stores this vitamin in fat cells. Thus, when you take a supplement, you can potentially increase the amount of vitamin D in your body to toxic levels. This is why it is critical to see a doctor and request a blood test for vitamin D deficiency before taking any supplements.
There are three main authorities that provide guidelines on how much vitamin D in the blood is safe: the Institute of Medicine, the Endocrine Society, and the Vitamin D Council. The table below summarizes their recommendations.7-9
The amount of supplement, if any, that a person should take depends on the current level of vitamin D in the blood. This is why it is critical to see a doctor and undergo a blood test for vitamin D deficiency before taking any supplements. Having too little or too much vitamin D is associated with health risks.10,11
If the amount of vitamin D in the blood reaches toxic levels, several severe health problems can result. The most common one is hypercalcaemia, which means too much calcium in the blood. This happens because vitamin D is responsible for calcium absorption in the body. In other words, if we have too much vitamin D in our blood, we also will get too much calcium in the blood. Too much calcium in the blood can lead to weak bones and kidney stones, as well as heart and brain problems. Other symptoms of excess vitamin D include dehydration, vomiting, decreased appetite, irritability, constipation, fatigue, and muscle weakness.
How much vitamin D is too much?
Because the effects of taking vitamin D supplements depend on how much vitamin D is already in the blood, it is difficult to give a single answer for how much is too much. According to the Institute of Medicine, a daily intake of 4000IU (100mcg) of vitamin D on an ongoing basis is harmful for the health of anyone over the age of eight. On the other hand, some experts claim that 10,000IU (250mcg) daily is still safe. However, there are case reports of side effects in people taking even less than 4000IU.10Despite these conflicting numbers, all the experts agree on the main recommendation: no one should take any amount of vitamin D without first undergoing a blood test for vitamin D deficiency.
If you do have a vitamin D deficiency, the results of the blood test will dictate the amount of vitamin D that is safe to take. Your doctor may prescribe a large dosage, such as 50,000IU, to be taken just once per month. Your body will store most of this large amount of vitamin in your fat cells, where the body can access it later as necessary. This allows you to maintain a healthy supply for days when you do not get enough sun.
Because vitamin D is fat-soluble, it is a good idea to take vitamin D supplements with moderately-fatty food, such as peanut butter, eggs, avocados, etc. Otherwise, your body may not absorb the vitamin properly.
Several studies have investigated the health risks of too much vitamin D.
Expand to read three studies on the health risks of taking too much vitamin D
One study, published in the Journal of Clinical Endocrinology & Metabolism in 2013, found that people who have less than 18ng/mL or more than 50ng/mL of vitamin D in the blood die sooner than people who have between 18 and 50ng/mL. In other words, people who have too much or too little vitamin D in the blood tend to die sooner than people who have the recommended amount.10
Another large study of 420,000 patients, which was also published in the Journal of Clinical Endocrinology & Metabolism in 2013, found that people with vitamin D levels above 36ng/mL were at higher risk for heart attack and death.10
A third large study of 247,574 patients, published in the Journal of Clinical Endocrinology & Metabolism in 2012, showed that people with vitamin D levels above 56ng/mL were at higher risk for death.10
These three studies suggest that a blood vitamin D level above 50ng/mL is harmful, since it can potentially lead to heart problems and earlier death. However, we must keep in mind that these studies are correlational--in other words, they cannot prove that vitamin D is what caused the health problems. To prove this, researchers would need to conduct a clinical trial. Still, from the data we currently have, it seems safe to keep your level of vitamin D between 30 and 50ng/mL.
In addition to the three studies above, a case study published in the Journal of Pediatric Endocrinology and Metabolism in 2014 demonstrated some effects of taking too much vitamin D. The report described a 12-year-old boy who had been taking six vitamin D supplements per day for one month. This dose was equivalent to 50,000IU/day, which is much higher than the recommended daily amount. The boy was admitted to the hospital with abdominal pain, constipation, and vomiting. Laboratory tests revealed high levels of vitamin D, kidney failure, and high blood pressure.12 The authors wrote, "[This] case report underline that self-medication with [over-the-counter] preparations can lead to the risk of organ dysfunction and even death. They must be prescribed only when needed and under strict medical control."12
Vitamin D is an important vitamin that may help to improve acne. Our bodies make vitamin D in the skin and obtain it from food or dietary supplements. While vitamin D deficiency poses health risks, taking too much vitamin D can cause severe and possibly fatal side effects. If you think you may have a vitamin D deficiency, see your doctor and request a blood test for vitamin D levels before taking any supplements. Ideally, the amount of vitamin D in the blood should be between 30 and 50ng/mL, and it is important not to exceed this level.
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- Reichrath, J. Vitamin D and the skin: an ancient friend, revisited. Exp Dermatol 16, 618 - 625 (2007).
- Kamen, D. L. & Tangpricha, V. Vitamin D and molecular actions on the immune system: modulation of innate and autoimmunity. J Mol Med 88, 441 - 450 (2010).
- Yildizgören, M. T. & Togral, A. K. Preliminary evidence for vitamin D deficiency in nodulocystic acne. Dermatoendocrinol 6, e983687 (2014).
- Lucas, R. M., Repacholi, M. H. & McMichael, A. J. Is the current public health message on UV exposure correct? Bull World Health Organ 84, 485 - 491 (2006).
- Cancer Council Australia. Risks and benefits of sun exposure. (2007).
- Vanchinathan, V. & Lim, H. W. A dermatologist's perspective on vitamin D. Mayo Clin Proc 87, 372 - 380 (2012).
- Ross, A. C., Taylor, C. L., Yaktine, A. L. & Del Valle, H. B. Dietary reference intakes for calcium and Vitamin D. National Academy of Sciences (2010).
- Holick, M. F. et al. Evaluation, treatment, and prevention of vitamin D deficiency: An endocrine society clinical practice guideline. J Clin Endocrinol Metab 96, 1911 - 1930 (2011).
- Heaney, R. P. Assessing vitamin D status. Curr Opin Clin Nutr Metab Care 14, 440 - 444 (2011).
- Korgavkar, K., Xiong, M. & Weinstock, M. A. Review: Higher vitamin D status and supplementation may be associated with risks. Eur J Dermatol 24, 428 - 434 (2014).
- Bouillon, R. et al. Optimal vitamin D status: A critical analysis on the basis of evidence-based medicine. J Clin Endocrinol Metab 98, 1283 - 1304 (2013).
- Conti, G. et al. Vitamin D intoxication in two brothers: Be careful with dietary supplements. J Pediatr Endocrinol Metab 27, 763 - 767 (2014).