Calcium and Vitamin D Supplements: Do You Need Them and Why?

A new study published Tuesday in JAMA showed that calcium and vitamin D supplements may not actually help prevent bone fractures. Unfortunately, preventing bone fractures is one of the reasons many people might want to take these kinds of supplements. But what are calcium and vitamin D supplements, anyway?

While it's easy enough to speak generally about the category, it's worth noting that dietary supplements, including ones with calcium and vitamin D, are not approved by the FDA in the same way that drugs are. That's not to say that every dietary supplement is useless—just that the FDA hasn't given any particular use the rubber stamp.

In short, there's a reason both ads and bottles of dietary supplements have some variation of these phrases: "These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease." Only drugs that have gone through an FDA approval process are allowed to make those kinds of medical claims.

There's no need to get calcium supplements if you can meet those recommended dietary intakes through the foods you eat. Dairy products are a major source of calcium; eight ounces of plain, lowfat yogurt has nearly half of the calcium a person needs in a day.

The recommended amount of calcium people should get from their diet does vary based on a person's age, according to the government's dietary guidelines. Children younger than three need about 700 milligrams of calcium every day. Slightly older children need at least 1,000 milligrams, while pre-teens, teenagers and adults need 1,300 milligrams.

However, most people don't get enough from their diet. According to a paper published in 2011, the median calcium intake for American men and women didn't come close to 1,300 milligrams—in fact, the median American got less than 1,000 milligrams per day, and the amount a person got decreased as they got older. About half of the people in the survey reported take a calcium supplement.

There are typically two forms of calcium found in supplements, according to the National Institutes of Health's (NIH) website: calcium carbonate and calcium citrate. Carbonate is more common and is meant to be taken with food; citrate is usually used by people with some gastrointestinal diseases. Carbonate-based supplements also have more calcium in them than those that are citrate-based; about 40 percent of the weight of a carbonate-based supplement comes from calcium atoms, compared to only about 21 percent in citrate-based supplements.

The study published Tuesday isn't the only one to question the utility of calcium supplements. As Newsweek reported in 2015, a study published in BMJ found that calcium supplements might not even improve bone density by a meaningful amount.

However, that's also not to say that calcium supplements are definitely useless or that they're useless for everyone. As Dr. Consuelo Wilkins, the executive director of a partnership between Meharry Medical College and Vanderbilt University, told Newsweek on Tuesday, supplements might still be important for certain populations. Some groups of people are particularly vulnerable to lower levels; she gave the example of African-Americans, who are more likely to have low vitamin D levels.