5 physical signs you're taking too much vitamin D
Take vitamin D: though many people are deficient in the nutrient, the rate of people exposed to vitamin D toxicity increased by 1,600% between 2005 and 2011, according to US Poison Control data.
The body can get vitamin D naturally from sunlight and foods like liver, but most people are deficient due to spending time indoors (and the fact that liver isn't a fan-favorite food), said Dr. Zhaoping Li, the director of the University of California, Los Angeles' Center for Human Nutrition.
"There are people taking really a lot," Li said, saying cancer patients have been swayed by a randomized clinical trial that people with cancer taking vitamin D supplements had a lower risk of dying compared to the placebo group. "We're talking about people taking 50,000 a day" — a dosage Li does not recommend.
Fortunately, Li said, overdosing on vitamin D is not as risky as vitamin A, which can swiftly cause liver toxicity and require an organ transplant. .
Too much vitamin D could, however, cause health problems like vomiting, constipation, and muscle cramps. One 54-year-old man experienced permanent kidney damage after overdosing on vitamin D supplements.
Doctors recommend taking 600 IU a day for most adults.
Dr. Eduardo Villamor, an epidemiology professor at the University of Michigan, said the recommended vitamin D allowance for most adults is 600 international units (IU), according to standards set by the Health and Medicine Division of the National Academies.
People over 70 years old can safely take 800 IUs.
Villamor said it's hard to get too much vitamin D without taking too many supplements. People can keep a healthy level naturally by choosing foods rich in vitamin D, like fatty fish and fortified products, and getting sun exposure.
Ryan Andrews, RD, principal nutritionist and adviser at Precision Nutrition, previously told Insider people who think they are vitamin D deficient should speak to their doctor before taking supplements to ensure they take the proper dose.
Here are 5 physical signs you're taking too much vitamin D:
You're always thirsty and constantly peeing.
Vitamin D helps regulate the body's calcium absorption, Li said.
But taking too much vitamin D can cause hypercalcemia, or when there's too much calcium in your blood. The kidneys work harder to filter out calcium, causing excessive thirst and frequent urination, according to Mayo Clinic.
Taking too much vitamin D can cause hypercalcemia, or abnormally high calcium in the blood, which can impact the kidneys, digestive system, bones, brain, and heart.
Too much calcium can also cause kidney stones and heart damage, Insider previously reported.
Villamor said other symptoms of hypercalcemia may be unspecific, and can include confusion, depression, and fatigue.
In one 2021 study, a 64-year-old man accidentally took 200,000 IU of vitamin D daily for an unspecified amount of time — more than 300% higher than the recommended daily dose.
He came into the emergency room in an "obtunded" state and could not provide detailed medical history. He remained agitated and confused for the first 10 days of hospitalization, but gradually improved after taking more calcium.
You have muscle aches and cramps.
Muscle aches, weakness, cramping, and twitching can all come from hypercalcemia, per Cleveland Clinic. Penn Medicine states hypercalcemia could lead to dehydration, which can cause muscle cramps.
You are falling down more.
Villamor said taking more than 4,000 IU of vitamin D can also increase the risks of fractures and falls.
If you're falling down more, or feel hard bumps on your breasts, fat, or muscles, you may be taking too much vitamin D.
You're constipated, nauseous, or vomiting.
Li said gastrointestinal problems are a common indicator that you might be taking too much vitamin D. Issues include nausea, vomiting, constipation, and dehydration.
"Your body's trying to get rid of the actual calcium being absorbed," Li said, referring both to GI problems and excessive urination. "Those are the major concerns of vitamin D toxicity — even if it's not as bad as vitamin A [toxicity], when you take a large quantity in pure forms, you have to worry, what does it do to the body?"