How an Increasingly Popular Supplement Landed a Man in the Hospital

A British man's overdose on vitamin D is a cautionary tale for people who are considering adding supplements to their lives, according to a paper published Tuesday in the journal BMJ Case Reports.

After a visit with a private nutritionist, the man began taking more than 20 over-the-counter supplements every day, including 50,000 international units (IU) of vitamin D three times a day. That's a dose hundreds of times higher than standard nutritional recommendations.

Within a month, the man began suffering from nausea, abdominal pain, diarrhea, and repeated bouts of vomiting, along with cramping in the legs and ringing in the ears.

The man, whose name was not disclosed, heard about the supplements from a radio talk show and contacted the nutritionist on the show afterward, said Dr. Alamin Alkundi, a coauthor of the report and an endocrinologist at William Harvey hospital in East Kent in the UK, who treated the man.

"Registration by regulator is not compulsory for nutritionists in the UK and their title is not protected, so anybody can practice as a nutritionist," Alkundi said in an email.

Unlike water-soluble vitamins, which the body can easily eliminate, vitamin D and its cousins A, E and K are stored in the liver and fat cells of the body until they are needed. Consuming well over the daily recommended dose can build up to toxic levels.

A 2017 study found 3 percent of Americans took more than the tolerable upper limit of 4,000 IU daily for adults, thus putting themselves at risk for toxicity. About 18 percent took more than 1,000 IU daily.

Too much vitamin D in the blood leads to hypercalcaemia, which occurs when the calcium level in your blood is above normal. The man in the BMJ case study was diagnosed with hypercalcaemia, which can weaken your bones, create kidney stones, and interfere with how your heart and brain work.

The man was hospitalized for eight days and treated with drugs to lower the levels of calcium in his blood. A followup two months later found his blood calcium levels had dropped to almost normal. While the man's vitamin D level had also significantly improved, it was still high, Alkundi said.

"A plan to periodically monitor both parameters in clinic was established to track the declining levels to normal levels. We have had contact with him and he reported (he feels) much better, but still not back to his normal self," Alkundi said.

"He is very eager for his story to be known to alert others," Alkundi added.

However, going into strong midday sunlight isn't advised due to the risk of skin cancer, so dermatologists and the AAP say it's best to use sunblock if you will be exposed for any prolonged length of time. Sunscreens can reduce the body's ability to process vitamin D.

Vitamin D supplementation may not be needed for many children and teens, the AAP said, since many foods such as milk, eggs, cereals and orange juice are often fortified with vitamin D. Breastfed infants should be given 400 IU of supplemental vitamin D daily, starting in the first few days of life and continuing until the baby is weaned to milk or formula fortified with vitamin D, the AAP advised.

If vitamin D supplements are being considered, daily levels of vitamin D obtained from food should be factored into the decision, experts caution. In addition to fortified foods, eggs, cheese, shiitake mushrooms, salmon, swordfish, tuna, rainbow trout and beef liver contain vitamin D, as does cod liver oil.

Anyone concerned about their vitamin D levels should have them evaluated by a doctor, experts say.