(Reuters Health)—Some adults in the U.S. who use supplements to get their daily requirement of calcium are taking higher doses than necessary, a recent study suggests.
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Researchers examined nationally representative survey data on dietary habits and vitamin and supplement use collected between 1999 and 2014 from 42,038 adults.
About one in 20 adults got a substantial portion of their daily calcium from supplements, the study found.
In the study’s first year, 2.5% of supplement users got more than the estimated daily amount of calcium necessary. This peaked at 6.7% of supplement users from 2003 to 2004, then dipped to 4.6% by 2013 to 2014.
“Supplemental calcium has potential benefits, particularly in relation to bone health, however, it may also put people at increased risk of kidney stones, cardiovascular disease and adverse gastrointestinal symptoms,” said senior study author Pamela Lutsey of the School of Public Health at the University of Minnesota in Minneapolis.
“This is in contrast to calcium consumed from dietary sources, which is generally well-tolerated and has been associated lower risk of fractures, colon cancer, kidney stones and hypertension,” Lutsey said by email.
For women up to age 50 and men up to age 70, total daily calcium intake from all sources of 800 milligrams is recommended to meet the estimated average requirements of most people, researchers noted March 9 in the journal Bone. After age 50 for women and 70 for men, this goes up to 1,000 milligrams a day. These intake estimates are based on the amount of calcium needed to promote bone health.
The upper tolerable limit of calcium supplementation is 2,500 milligrams a day for adults up to age 50, and 2,000 milligrams a day after that. Larger doses are linked to an increased risk of soft tissue damage.
By the end of the study period, only 0.3% of supplement users were taking more than the upper tolerable limit, down from 1.2% in 2007 to 2008.
Women, non-Hispanic white people and older adults were more likely than other individuals to take too much calcium.
The study wasn’t a controlled experiment designed to prove whether or how calcium supplements might help or harm health. Another limitation is that researchers relied on survey participants to accurately recall and report what they ate, and to show all of the vitamins, minerals and supplements they took.
Still, results add to the evidence that use of calcium supplements is declining, in part out of safety concerns, said Dr. Kurt Kennel, a nutrition researcher at the Mayo Clinic in Rochester, Minnesota, who wasn’t involved in the study.