Is It Safe to Take Calcium and Vitamin D Supplements Together?

Some research claims these two supplements taken together could be dangerous—but should you be worried?

More than half of Americans take a dietary supplement of some sort, and calcium and vitamin D are among the most common. In fact, research published in the Journal of Nutrition found that 37% of Americans took vitamin D and 43% took a calcium supplement.

However, research published in August 2019 in the Annals of Internal Medicine found that taking calcium and vitamin D supplements together might increase your risk of having a stroke. This finding was published in a review of what's currently known about the effects of supplements on our health.

What should you know about taking these supplements together? A cardiologist weighs in.

Why We Need Calcium

Ninety-nine percent of the body's calcium supply can be found in one's teeth and bones. Calcium allows your blood to clot and your muscles to contract in addition to keeping your bones healthy.

Women 50 years old and younger need to consume 1,000 milligrams of calcium each day, according to the National Osteoporosis Foundation. Women 51 and up need to add another 200 milligrams to that.

Dairy products, including cheese, milk, and yogurt, have high levels of calcium.

Why We Need Vitamin D

Vitamin D, which is important for children and adults, also plays a part in protecting bones and helps support your muscles. Without adequate levels of vitamin D, you have an increased risk of breaking bones as you get older, the National Osteoporosis Foundation says.

Among the most popular ways to get vitamin D is going outside. When sunlight reaches your skin, your body makes vitamin D and stores it. Additionally, you can get it from fatty fish, including wild-caught mackerel, tuna, and salmon. Vitamin D can also be found in orange juice, fortified cereals, soymilk, and dairy products, including milk.

What Does the Research Say?

The August 2019 Annals of Internal Medicine study isn't the first time the combination of calcium and vitamin D has been scrutinized. "It's been looked at a lot," Stephen Kopecky, MD, a cardiologist at Mayo Clinic, told Health.

Dr. Kopecky explained that you shouldn't panic if you've been taking vitamin D and calcium supplements together. The authors of the 2019 study looked at previously published evidence concerning how supplements affect our health.

In addition, a study published in the July/September 2019 issue of the Methodist Debakey Cardiovasc Journal noted there is some concern related to the use of vitamin D and calcium supplements together but called the concern "inconclusive."

But Dr. Kopecky said many of the studies that have looked at the use of vitamin D and calcium supplements rely on follow-up data that lacks precision. If a study participant died before the data was gathered, for example, his or her family member ended up filling out a questionnaire about their deceased relative's health. Questionnaires are, of course, subject to human error.

Dr. Kopecky said studies that don't rely on questionnaires later found that use of calcium and vitamin D supplements did not increase one's risk of stroke or heart attack. "That has no correlation whatsoever," said Dr. Kopecky. (However, a number of factors can increase your risk of having a stroke, including being overweight, binge drinking, and not getting enough exercise.)

He added that if you've been told to take calcium and vitamin D supplements by your healthcare provider, you shouldn't stop. If you've been taking the supplements on the advice of someone else, though, you might want to reevaluate. "I would speak to a caregiver or primary care provider. Say, 'Do I really need this stuff?'"

What's the Best Way to Get Vitamin D and Calcium?

To reiterate, you shouldn't stop taking supplements your healthcare provider has recommended. But if you're worried about your calcium and vitamin D intake, and you currently don't take either of the supplements, try getting the recommended amount of calcium and vitamin D via lifestyle changes rather than pills, said Dr. Kopecky.

"A pill doesn't make up for our deficient lifestyle. That's what every study has shown," said Dr. Kopecky.

"It's always better to get it in your diet if you can. People tend to take supplements to make up for their diet. [Therefore, supplement use] can be a marker of a bad diet."

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