A growing number of Americans has been found to be taking too much vitamin D supplements over the past 15 years, raising concerns among doctors about its potential health risks.
Vitamin D plays a crucial role in promoting good health. An adequate amount of the nutrient helps make it easier for our bodies to absorb calcium, preventing us from developing serious conditions such as osteoporosis.
However, taking high doses of the vitamin can have an opposite effect. If our bodies have too much of the nutrient, we can suffer from an overabsorption of calcium, which could damage our organs. This is why people are only allowed a maximum of 4,000 International Units (IU) of vitamin D a day before they develop adverse effects.
In a study featured in the journal JAMA, researchers discovered that more adult Americans are taking high doses of vitamin D between 1999 and 2014. The number of people taking 1,000 International Units (IU) or more of the nutrient jumped from 0.3 percent in 1999-2000 to an alarming 18.2 percent in 2013-2014.
The findings are particularly alarming since the recommended dietary allowance for the supplement is set at only 600 IU a day for adults up to the age of 70. Those who are beyond the age of 70 can take 800 IU of vitamin D a day.
Dangers Of Taking Too Much Vitamin D Supplements
Study co-author Pamela Lutsey from the University of Minnesota explained that vitamin D is needed for bone metabolism. It helps make sure that the body absorbs enough calcium and maintain proper levels of calcium and phosphate in the blood.
Having enough vitamin D levels can help protect the body from health problems such as osteoporosis and osteomalacia (bone softening). Studies also show that the nutrient also prevents muscle and bone pain, and retards the onset of type 1 diabetes.
The most well-known source of vitamin D is sunlight. The body produces the nutrient using a chemical reaction whenever the skin is exposed to sunlight.
The vitamin can also be found in certain foods, such as animal meat and dairy, though this is not enough to meet the body's needs. This is why people depend on vitamin D supplements so that they'll have healthy amounts of it.
However, taking too much of the vitamin can also be dangerous, as it can cause the body to absorb excessive amounts of calcium. As Lutsey pointed out, this can lead to harmful levels of calcium in the body's soft tissues, such as the kidneys and the heart.
To find out how many people are taking high doses of vitamin D, Lutsey and her colleagues examined 39,243 adult Americans who were using vitamin supplements from 1999 to 2014 to know how many were taking daily doses of more than 1,000 IU of the vitamin and how many were taking more than 4,000 IU.
The researchers discovered that women, the elderly, and white people were among those who were taking high doses of vitamin D.
No adult Americans age 70 and older were found to be taking at least 4,000 IU of vitamin D supplements daily in 2007. However, the number rose to 6.6 percent by 2013 and 2014.
By the time the study wrapped up, 6.6 percent of Americans aged 60 to 69 were taking at least 4,000 IU of the nutrient as well. The same goes for 4.2 percent of all women and 3.9 percent of all white people who participated in the program.
Lutsey and her colleagues noted that such high doses of vitamin D can lead to serious adverse effects, especially when used along with calcium supplements. Evidence also suggest that high doses can also increase a person's risk of developing pancreatic and prostate cancers.
While the study offers insights into the potential side effects of taking too much vitamin D, it does have limitations. It wasn't able to examine the various benefits and risks of taking varying amounts of vitamin supplementation.
Participants were also asked to accurately recall their supplement use to report their progress. They were asked to bring in the pill bottles they used to support their report.
Close to one in every five American adults take supplements for their vitamin D needs. The nutrient is particularly important for adults over the age of 50. Younger people who don't get enough sunlight and those who live in higher latitudes can also benefit from vitamin D supplements.