Man hospitalized after overdosing on vitamin D: What is vitamin D toxicity?

Check the Canadian guidelines to find out how much vitamin D you should be taking daily. (Photo via Getty Images)
Many Canadians don't get enough vitamin D naturally, but too much can lead to toxicity. (Photo via Getty Images)

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Contact a qualified medical professional before engaging in any physical activity, or making any changes to your diet, medication or lifestyle.

Vitamin D is essential to our overall health. It keeps our bones strong and helps our bodies absorb calcium. However, what happens when you take too much?

A British man found this out the hard way after taking more than 300 times the recommended daily amount.

After a trip to a nutritionist, the man began taking more than 20 over-the-counter supplements daily. Within a month, the man began suffering from nausea, abdominal pain, diarrhea and vomiting, along with ringing ears and leg cramps — all symptoms of vitamin D toxicity. He lost 28 pounds and was admitted to the hospital.

Although the man stopped taking the supplements once he began experiencing symptoms, the effects continued for three months.

According to Dr. Michael Reider, a professor of pharmacology at Western University in London, Ont., there are many reasons why extra vitamin D might be helpful, but explains "there can be too much of a good thing."

Read on to learn the signs and symptoms of vitamin D toxicity and how you can prevent this condition.

Foods like dairy products are often fortified with vitamin D. (Photo via Getty Images)
Fatty fish like salmon, tuna and sardines are high in vitamin D. (Photo via Getty Images)

What is vitamin D?

Vitamin D is a nutrient we eat and a hormone our bodies make. It helps our bodies absorb and retain calcium and phosphorus, which help to build and maintain strong bones. It is widely available through exposure to the sun.

According to the Government of Canada, vitamin D has been shown to reduce inflammation, control infections and slow cancer cell growth.

There are two main forms of vitamin D: vitamin D2 and D3. Vitamin D2 is plant-based and usually by prescription, whereas D3 is animal-derived and available over the counter.

There are few foods that contain high amounts of vitamin D. The best sources are fatty fish like salmon, sardines and tuna. Smaller amounts can also be found in egg yolks, cheese and beef liver. Additionally, dairy products and cereals are often fortified with vitamin D.

What is vitamin D toxicity?

Vitamin D toxicity, also called hypervitaminosis D and vitamin D intoxication, is typically caused by ingesting too many vitamin D supplements, rather than by diet or sun exposure.

This condition will not happen through sun exposure because our bodies regulate the amount of vitamin D produced and absorbed by the sun. You also can’t get this condition from diet or fortified foods as they don’t contain large enough amounts of vitamin D. 

Shot of unhealthy young woman with stomachache leaning on the bed at home.
Vitamin D toxicity can lead to vomiting, loss of appetite, dehydration, muscle weakness and kidney stones. (Photo via Getty Images)

How do you know if you're taking too much vitamin D?

Having too much vitamin D in your body can lead to a buildup of calcium in your blood, a condition called hypercalcemia.

Symptoms of hypercalcemia include vomiting, loss of appetite, dehydration, muscle weakness and kidney stones. In more serious cases, this condition can cause heart damage. Unfortunately, this can go unnoticed and buildup slowly over many years.

To check if a patient is suffering from vitamin D toxicity, a doctor will do a blood test to see if there's abnornal levels of vitamin D and calcium in the blood. If a person suffers from this condition, they are recommended to stop taking all vitamin D and calcium supplements and eat fewer foods that are rich in this vitamin.

Although the British man stopped taking the vitamin D supplements, his levels were still high three months later. Reider believes it's because vitamin D is a fat-soluble vitamin and takes longer to process through our bodies.

"What happens is vitamin D is stored in the fat so it doesn't go away really quickly and that's why this guy in the U.K. took weeks and weeks to get better because it lingers around a long time," Reider told Yahoo Canada.

Woman enjoying the sunshine during the break between exercises
Vitamin D toxicity is caused by ingesting too many supplements, not by diet or sun exposure. (Photo via Getty Images)

How much vitamin D should you be taking?

Due to the Canadian climate, Reider says it can be tough for Canadians to get enough vitamin D, so many people benefit from supplements — if taken in the right dose.

For healthy adults, Health Canada recommends 600 international units (IU) of vitamin D per day up to the age of 70, and after 70 that increases to 800 IU. They also list the tolerable upper intake level as 4,000 IU a day as the maximum amount one can take without causing harmful effects.

"Senior citizens don't convert vitamin D in the skin as efficiently as younger people do," Reider explains.

Speak to your doctor

While some people are required to take a higher dose of vitamin D due to a health condition, Reider recommends speaking to your family doctor or a registered nutritionist before changing your daily regimen.

"A lot of things are good in the right quantity, pretty much everything is bad in the wrong quantity. So don't assume natural means safe, use common sense, and get advice from the professionals," he adds.

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