In Germany, about every second person is said to suffer from a vitamin D deficiency. As a result, more and more people are taking vitamin supplements, often in anticipation and fear of possible deficiency symptoms. However, the increased use of vitamin D treatments has led to a significant increase in the number of reports of vitamin D poisoning, most of which (75%) have been issued since 2010. (7)
It is therefore essential to pay attention to the dosage in order not to risk a vitamin D overdose. Otherwise, serious health consequences can be expected. For this reason we have tried to explain to you what vitamin D is, its effects, its sources. Most importantly, we have detailed the details of a sun hormone overdose.
the essentials in brief
- Adequate dietary intake (excluding solar synthesis, which accounts for 80-90% of the intake of this hormone) is 20 µg of vitamin D per day for an average person, which is 800 international units. An overdose of vitamin D represents regular intake beyond this recommendation. The stage of vitamin D toxicity to the body is believed to begin with chronic total intake of approximately 40,000 IU/day or 1000 micrograms.
- A vitamin D overdose through food is impossible because the hormone is too rarely found in food. The sun cannot lead to poisoning either, because UV rays break down excess vitamins produced by the body. Only dietary supplements that contain vitamin D can contribute to the excess. It is therefore necessary to regulate them and consult a doctor to know the levels of vitamin D in the body.
- Vitamin D overdose often leads to hypercalcemia (the body absorbs too much calcium from food and breaks down more calcium from the bones.) Consequences of excess include loss of appetite, nausea and vomiting, excessive thirst, increased urination, feeling weak, Nervousness, headaches and high blood pressure, sometimes even kidney stones and damage.
Definition: What is vitamin D?
Vitamin D is a hormone made up of a group of fat-soluble vitamins called calciferols. Among the best known and most important are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). (1)
The vitamin D molecule is often associated with the sun vitamin. (Image Source: Christina Victoria Craft / Unsplash)
And for a good reason:
About 90% of vitamin D is usually produced by the body, more precisely via the skin, which absorbs the UV radiation from sunlight. (1)
For this reason, it is also recommended to expose yourself to the sun with as much exposed skin as possible, to maximize synthesis, for a minimum of 5 and a maximum of 25 minutes a day. (2)
Background: What you should know about a vitamin D overdose
In order for you to understand how a vitamin D overdose can occur and what precautions you can take in this regard, you should learn more about the background of vitamin D.
Therefore, we have selected the most frequently asked questions and want to offer you more insight into this topic.
What role does vitamin D play in the body?
One of the main functions of vitamin D for the human body is its role in bone metabolism. This vitamin contributes to the absorption of calcium and phosphate from the intestine and their incorporation into the bones. (1)
Vitamin D is therefore of crucial importance for the mineralization of the bones in the human skeleton. (1)
In addition, the hormone is required for other metabolic processes such as protein formation and the regulation of many genes. (1)
What is a vitamin D overdose?
An overdose of vitamin D represents a regular intake that is higher than the maximum daily recommended total intake set by the EFSA, for example. (2)
However, this overdose cannot be achieved through prolonged exposure to the sun. (2)
This can only happen through food intake, i.e. excessive intake of vitamin D supplements. (2)
But is too much vitamin D harmful?
This excess can lead to serious health consequences.
In fact, it is harmful in that it can cause acute nausea and vomiting, loss of appetite, and abdominal cramps in the short term, and kidney damage, cardiac arrhythmia, and hypercalcemia in the long term. (1)
When is vitamin D considered an overdose?
The German Society for Nutrition has estimated the recommended adequate intake from diet alone (without synthesis from sunlight) at 20 µg of vitamin D per day for an average person, which is 800 international units. (1)
It should be noted that self-synthesis accounts for 80 to 90% of nutrient intake when the person is regularly exposed to natural light. Nutrition, on the other hand, plays only a relatively minor role with an estimated share of around 10 to 20%. (1)
The authors of an overdose study suggest that the stage of vitamin D toxicity to the body begins with chronic intake of about 40,000 IU/day, or 1000 micrograms. This includes total intake from sunlight as well as from diet and supplementation. (6)
How is an excess of vitamin D recognized?
Vitamin D levels are determined by measuring the concentration of 25-hydroxyvitamin D, written "25(OH)D", in the blood. This content can be given in units of nmol/l or ng/ml.
An overdose is therefore mainly determined by this test.
It is estimated that levels of 25(OH)D greater than 125 nmol per liter of blood or greater than 50 ng per ml of blood represent a potential overdose of this molecule. (1)
What types of vitamin D poisoning are there?
In a way, there are different types of vitamin D overdose.
In fact, there are several different stages in the body's supply of this hormone. Here is a summary table:
|category||Amount in nanomoles per liter||Amount in micrograms per liter|
So on the one hand you have the surplus, which is more harmless and easier to remedy than poisoning with the highest vitamin D content in the blood.
Hypersensitivity to vitamin D
Third, there is hypersensitivity to vitamin D, a phenomenon often confused with vitamin D toxicity. The most common form is primary hyperparathyroidism. (3)
Certain diseases such as tuberculosis and other specific types of cancer cause this hypersensitivity to vitamin D, thus favoring an excess and its consequences. (3)
What are the symptoms of a vitamin D overdose?
Vitamin D overdose often leads to hypercalcemia, depending on how much the recommended value is exceeded. (9)
An excess of vitamin D therefore causes the body to absorb too much calcium from food and breaks down more calcium from the bones. (8th)
As a result, symptoms of a vitamin D overdose may include:
- loss of appetite
- nausea and vomiting
- A strong, unquenchable thirst
- A need to urinate more
- A feeling of weakness
- Tendency to nervousness and high blood pressure
- Kidney stones and damage
Therefore, it's better to see a doctor to assess your vitamin D status than to supplement yourself. (8th)
What are the causes of vitamin D intoxication?
As already mentioned, vitamin D enters the body through the sun's UV radiation, through diet and recently also through medication and dietary supplements that partially (multivitamin) or specifically contain vitamin D. (2)
It is at this last crucial point that the overdose is very often played out.
Sun can not lead to poisoning
As for the synthesis of vitamin D from the sun, there is no danger of excess and intoxication for humans. In fact, sunlight itself has been shown to deplete any overdose of vitamin D one might be exposed to. (10)
Food overdose is not possible
Similarly, dietary intake of vitamin D in excessive amounts is quite difficult.
In natural foods, vitamin D overdose can even be considered impossible, as very few foods contain large amounts of vitamin D. (Image Source: Supplement Review/Unsplash)
However, there are some of them:
|food category||food example||Vitamin D Quota (micrograms per 100 grams)|
|Dairy products||Processed cheese (45% fat content)||3.1|
|Milk (3.5% fat content)||0.1|
|Meat from land animals||lamb liver||2|
|raw vegetables||Morel and porcini mushroom||3.1|
|fats||margarine and butter||up to approx. 2.5|
Vitamin D supplements critically questioned
As previously mentioned, meeting your vitamin D needs can be difficult as there are few foods that are high in vitamin D. This can be tempting to supplement, especially if one has a sedentary lifestyle away from sunlight, which would otherwise activate epidermal production. (11)
In fact, it's much easier to take too much vitamin D if you consume capsules and other drug solutions containing vitamin D over a period of time. (2)
Because these elements are often very concentrated, playing on people's fears of deficiency, and providing very general recommendations for vitamin D intake that are not tailored to each person's individual profile, it is easy to make a dosing error.
And repeated over several days, weeks, or even months, this can undoubtedly lead to a state of overdose or even intoxication for the individual.
What are the consequences of hypervitaminosis D?
Hypercalcemia is the main disease associated with overexposure to vitamin D and is therefore also responsible for most symptoms of vitamin D toxicity. (3)
As a result, due to the high levels of calcium caused by excess vitamin D, the body tries to store calcium wherever it can, mainly in the kidneys, lungs, heart and also in the blood vessels. (8th)
Therefore, as already mentioned, the first symptoms of vitamin D toxicity include eating and gastrointestinal disorders such as anorexia, diarrhea, constipation, nausea and vomiting. (3)
Bone, joint and muscle pain, drowsiness and persistent headaches and sometimes an irregular heartbeat have also been reported.
Loss of appetite, excessive thirst, combined with an increased urge to urinate, especially at night, a feeling of weakness, nervousness and itching are other possible consequences of a vitamin D overdose. (3). All this massively exhausts the body! (Image Source: Adrian Swancar / Unsplash)
After all, in the worst cases, kidney stones, lesions or even kidney failure are possible. (3.8)
What treatments are there for vitamin D overdose?
In order to treat a possible vitamin D overdose, it must be diagnosed through a blood test in a doctor's office.
If the overdose is detected, measures are taken:
- You should stop taking vitamin D supplements. (9)
- Intravenous Fluid Intake (Normal Saline) (12)
- Prescribing pharmaceutical products (9)
- Medications such as corticosteroids or bisphosphonates (12)
Initially, vitamin D toxicity is treated by suppressing vitamin D supplements until the effects of high blood calcium levels are eliminated. (9)
After that, fluid intake and drugs (corticosteroids or bisphosphonates) that fight bone resorption lower calcium levels. (12)
However, possible kidney damage or already established metastatic calcifications may not be curable or only partially curable. (12)
How to avoid vitamin D overdose?
The best way to avoid a state of excessive vitamin D consumption is precisely not to take a supplement unless there is a medical recommendation for you to do so.
You can eat normally and get out in the sun without much effort, as long as you don't intentionally only eat vitamin D-rich foods and use a sunscreen that reduces the absorption of UV rays.
So no big worries on this side, just stay sane.
However, here is a cautionary chart of doses of vitamin D by age:
|Old||Vitamin D intake in the absence of autonomic synthesis (in µg/day)|
|up to 12 months||10|
|1 to 14 years||20|
|15 to 64 years||20|
|from 65 years||20|
Vitamin D overdose is a phenomenon of growing concern as more and more cases are reported. Perhaps we are focusing too much on a deficiency in this hormone these days, and we certainly believe that "better too much than too little".
However, this is not the case here. An overdose has as many downsides as a deficiency, plus the fact that we don't really know what effects it can actually have. Whereas the deficiency is much better known, highlighted and thus prevented. The excess should be taken seriously, as a chronic overdose of vitamin D really makes life more difficult and can even have serious consequences. It is therefore imperative to take precautions against it by adhering to the usual doses.
Dietary supplements should be observed with caution as it is easy to overdose on them. If this is respected, the danger is very limited. In addition, it makes sense to see a doctor to make a diagnosis and really know your vitamin status.
- Robert Koch Institute. (2019, January 25). Answers from the Robert Koch Institute to frequently asked questions about vitamin D. rki.de.
- German Society for Nutrition e. V. (2012, October 22). Selected questions and answers about vitamin D. dge.de.
- Alshahrani F, Aljohani N. Vitamin D: deficiency, sufficiency and toxicity. nutrients. 2013;5(9):3605-3616. Published 2013 Sep 13. doi:10.3390/nu5093605
- Haddock, L.; Corcino, J.; Vazquez, MD 25 OHD serum level in the normal Puerto Rican population and in subject with tropical sprue and parathyroid disease. Puerto Rico Health Sci. J. 1982, 1, 85-91.
- Krause, R.; Buhring, M.; Hopfenmuller, W.; Holick, MF; Sharma, AM Ultraviolet B and blood pressure. Lancet 1998, 352, 709-710.
- Vieth, R. Vitamin D supplementation, 25 hydroxy-vitamin D concentrations, and safety. At the. J.Clin. nutr. 1999, 69, 842-856.
- Taylor PN, Davies JS. A review of the growing risk of vitamin D toxicity from inappropriate practice. Br J Clin Pharmacol. 2018;84(6):1121-1127. doi:10.1111/bcp.13573
- Feichter, M. (2019, October 3). Vitamin D: overdose. NetDoctor.
- MSD manuals. (2019, October). Vitamin D excess. MSD Manual Edition for Patients.
- Mawer, EB, Hann, JT, Berry, JL, & Davies, M (1985). Vitamin D metabolism in patients intoxicated with ergocalciferol. Clinical Science, 68(2), 135-141.
- Felchner, C. (2019, September 30). Vitamin D – foods high in content. NetDoctor.
- MSD manual. (2018, March). Vitamin D. MSD Manual Professional Edition.
- Felchner, C. (2019, September 28). Vitamin D. NetDoctor.