Vitamin D is the healthy vitamin we get from sunshine, but it can have a dark side. This is extremely important for your health. It plays several roles to maintain the health of your body’s cells and their normal functioning.
Most people do not get enough vitamin D, so supplements are common.
However, it is also possible, although rare, to accumulate too much vitamin D and reach toxic levels in your body.
The main consequence of vitamin D toxicity is an accumulation of calcium in the blood (hypercalcemia), which can cause nausea and vomiting, frequent weakness and urination. Symptoms can progress to bone pain and kidney problems, such as calcium stone formation.
Vitamin D helps calcium absorption, immune function, and protection of bone, muscle and heart health. It occurs naturally in food. The body produces it when there is an exposure of the skin to the sun. In fact, your body regulates the amount of vitamin D produced by sun exposure. Furthermore, fortified foods do not even contain large amounts of vitamin D.
However, apart from fatty fish, there are few foods rich in vitamin D. In addition, most people do not have adequate exposure to the sun to produce enough.
So, deficiency is very common. In fact, there is an estimation that around one billion people in the world do not consume enough of this vitamin.
Supplements are very common and both vitamin D2 and vitamin D3 can be taken as a supplement. The body produces D3 in response to sun exposure. It is found in animal products, while vitamin D2 is found in plants.
Vitamin D3 increases blood levels significantly more than D2. Studies have shown that every 100 additional IU of vitamin D3 consumed per day will increase your blood vitamin D level by an average of 1 ng/ml (2.5 nmol / l).
However, taking extremely high doses of vitamin D3 for long periods of time can cause excessive accumulation in your body.
Vitamin D poisoning occurs when blood levels exceed 150 ng/ml (375 nmol/l). The vitamin is stored in body fat and slowly released into the bloodstream. Thus effects of toxicity may last several months after stopping treatment with supplements.
It is important to keep in mind that toxicity is rare and occurs almost exclusively in people who take long-term high-dose supplements without controlling their blood levels.
It is also possible to inadvertently consume too much of it by taking supplements with amounts much higher than those indicated on the label.
On the other hand, it can reach dangerously high blood levels only through diet and sun exposure.
A Case Study
For example, a team of doctors in Toronto reported the case of a 54 year old man who had developed kidney damage after taking too much vitamin D. This is a warning story for consumers, medical experts say.
“Although vitamin D toxicity, also called hypervitaminosis D is rare due to a wide therapeutic range, its widespread availability in several over-the-counter formulations may pose a substantial risk to uninformed patients,” said the study co-author, Dr. Bourne Auguste. He is a clinical researcher in home dialysis at the Toronto General Hospital and the University of Toronto.
As reported in the Canadian Medical Association Journal, the man met with the doctors after returning from his vacation. On his vacation in Southeast Asia, he spent much of his time sunbathing.
The tests showed that the man had high blood levels of creatinine, a marker of kidney damage or dysfunctions.
Then, the patient was referred to a kidney specialist and underwent additional tests.
Doctors discovered that a naturopath prescribed too much vitamin D to the man, even though he had no deficiency and had no history of bone loss.
In 30 months, the man had taken between 8 and 12 drops of vitamin D, between 8,000 and 12,000 international units (IU), per day.
How Much Vitamin D is too much?
The recommended daily amount is 400 to 1,000 IU, and a higher amount (800 to 2,000 IU) is recommended for adults at high risk for osteoporosis and elderly people.
The patient in the above case study far exceeded these doses, which resulted in extremely high levels of calcium in the blood. It is these high levels of calcium in the blood that caused the damage to the kidney, Auguste’s team said.
“Patients and doctors should have better information about the risks of unhindered use of vitamin D,” the study authors concluded.
Dr. Maria DeVita directs nephrology (renal medicine) at Lenox Hill Hospital in New York. Rereading the case report, he said that “consumption of too much vitamin D, as in many supplements, can have disastrous adverse effects.”
DeVita said: “Vitamin D is necessary for the development and maintenance of strong bones, but the message to remember is that too much of something good is not good.”
Side Effects Of too much Vitamin D
Read more to find out the 6 main side effects of too much vitamin D.
1. High Blood Levels
Achieving adequate levels of vitamin D in your blood can help boost your immunity and protect you from diseases such as osteoporosis and cancer.
However, there is no agreement on an optimal range for adequate levels.
Although a vitamin D level of 30 ng/ml (75 nmol/l) is generally adequate, the Vitamin D Council recommends maintaining levels of 40 to 80 ng/ml (100 to 200 nmol/l). They indicate that anything exceeding 100 ng/ml (250 nmol/l) can be harmful.
As more people take its supplements, it is rare to find someone with very high blood levels of this vitamin.
A recent study examined data from more than 20,000 people over a 10-year period. It was found that only 37 people had levels above 100 ng/ml (250 nmol/l). Just one person had true toxicity, at 364 ng/ml (899 nmol/l).
In one case study, a woman had a level of 476 ng/ml (1,171 nmol/l) after taking a supplement giving her 186,900 IU vitamin D3 daily for two months.
This was 47 times the upper limit of recommended safety generally of 4000 IU per day.
The woman was admitted to the hospital after experiencing fatigue, forgetfulness, nausea, vomiting, slurred speech, and other symptoms.
Although only extremely high doses can cause toxicity so quickly, even the strongest advocates of these supplements recommend an upper limit of 10,000 IU per day.
2. Bone Loss
Since vitamin D plays an important role in calcium absorption and bone metabolism, it is essential to consume enough to maintain strong bones.
However, too much vitamin D can affect bone health.
Although many symptoms of excess vitamin D are attributed to high levels of calcium in the blood, some researchers suggest that megadoses can lead to low levels of vitamin K2 in the blood (source).
One of the most important functions of vitamin K2 is to maintain calcium in the bones and out of the blood. It is thought that very high levels of vitamin D can reduce the activity of vitamin K2.
To protect against bone loss, avoid taking too much vitamin D supplements and take vitamin K2 supplements. You can also eat foods rich in vitamin K2, such as grass-fed dairy and meat.
3. Stomach Pain, Diarrhea and Constipation
Constipation, stomach pain, and diarrhea are common digestive problems of food intolerance or irritable bowel syndrome.
However, they can also be an aftereffect of high calcium levels due to too much vitamin D.
These symptoms may occur in people receiving high doses of the vitamin to cure the deficiency. As with other symptoms, responses seem to be individualized even when blood levels increase similarly.
In a case study, a boy developed constipation stomach pain after taking too much vitamin D supplements. His brother developed high blood levels without any other symptoms (source).
In another case study, an 18-month-old boy who received 50,000 IU of vitamin D3 for 3 months had diarrhea, stomach pain, and other symptoms. These symptoms disappeared after the child stopped taking supplements (source).
4. Nausea, Vomiting, and Lack of Appetite
Many side effects of too much vitamin D are related to excess calcium in the blood.
These include nausea, vomiting and a lack of appetite.
However, these symptoms do not occur in all people with high calcium levels.
One of the following people followed 10 people who developed excessive calcium levels after taking high doses of the vitamin to correct the deficiency.
Four of them had nausea and vomiting, and three lost their appetite (Source).
Similar responses to too much vitamin D have been reported in other studies. One woman had nausea and weight loss after taking care of the disease.
Importantly, these symptoms occurred at extremely high doses of vitamin D3, resulting in calcium levels above 12 mg/dl (3.0 mmol/l).
5. High Levels of Calcium in the Blood.
Vitamin D aids your body to absorb calcium from the foods you consume. In fact, this is one of his most important roles.
However, if the intake is excessive, the level of calcium in the blood can reach levels that can cause
Symptoms of hypercalcemia or high levels of calcium in the blood include:
- Digestive difficulties, such as vomiting, nausea, and stomach upset
- Fatigue, dizziness, and confusion
- Excessive thirst
- Frequent urination
The normal range of calcium in the blood is between 8.5 and 10.2 mg/dl (2.1 to 2.5 mmol/l).
In one case study, an older man with dementia, who received 50,000 IU of the vitamin daily for 6 months, was hospitalized over and over again with symptoms related to high calcium levels.
Another case showed two men took poorly labeled vitamin D supplements, resulting in blood calcium levels of 13.2-15 mg/dl (3.3-3.7 mmol/l). In addition, it took them a year to normalize their levels after they stopped taking supplements.
6. Kidney Failure
Too much vitamin D intake often leads to kidney damage.
In one case study, a man was hospitalized for kidney failure, elevated blood calcium levels, and other symptoms that occurred after his doctor prescribed a vitamin D injection.
In fact, most studies have reported moderate to severe kidney damage in people developing vitamin D toxicity.
Another study of 62 people who received excessively high doses of vitamin D, each person had kidney failure whether they had an already existing kidney problem or not (source)
You can treat kidney failure with oral or intravenous hydration and medications.
Summary and Recommendation
This vitamin is extremely important for your overall health. Even if you follow a healthy diet, you may need supplements to achieve optimal blood levels.
However, it is also possible to have too much good.
Avoid excessive doses or too much vitamin D. In general, 4,000 or less per day are considered safe, provided your blood values are controlled.
Also, be sure to purchase supplements from licensed manufacturers to reduce the risk of an accidental drug overdose.
If you are taking its supplements and have any of the symptoms listed in this article, consult a health care practitioner as soon as possible.
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