Most healthy, postmenopausal women don't need to take calcium or vitamin D supplements to prevent broken bones, a U.S. advisory group concludes.
Now the U.S. Preventive Services Task Force has reviewed research on the supplements and concluded that taking 400 IU of vitamin D or less and 1,000 milligrams of calcium seems to slightly increase the risk for kidney stones in postmenopausal women and should not be taken.
There wasn't enough evidence to judge the effects of daily supplements with more than 400 IU of vitamin D and more than 1,000 milligrams of calcium.
For men and premenopausal women, Dr. Virginia Moyer of Baylor College of Medicine and her panel also found a lack of evidence for fracture prevention.
"Regrettably, we don't have as much information as we would like to have about a substance that has been around a long time and we used to think we understood," said Dr. Virginia Moyer of the Baylor College of Medicine, who heads the task force. "Turns out, there's a lot more to learn."
Last year, the Endocrine Society also concluded that the non-skeletal benefits of vitamin D are unclear.
Unlike that group, the task force's recommendations were based on hard end points of fractures rather than blood levels of vitamin D, Marion Nestle of New York University and Malden Nesheim of Cornell University in New York said in a commentary published with the study in Monday's Annals of Internal Medicine.
Re-think calcium and vitamin advice
From a nutritional perspective, Nestle said it's important to consider the diet as a whole rather than focusing on a single nutrient. The amount of vitamin D that we absorb from sunlight on the skin is another key factor although it is hard to measure.
The multiple recommendations from different groups confuse health care practitioners and the public, the commentary said.
The task force's "cautious, evidence-based advice should encourage clinicians to think carefully before advising calcium and vitamin D supplementation for healthy individuals," Nestle and Nesheim concluded.
These recommendations don't apply to those at high risk of weak bones, including older adults who have previously broken a bone and are at risk for another fracture, said Dr. Sundeep Khosla of the American Society for Bone and Mineral Research. Those people should consult a doctor, said Khosla, a bone specialist at the Mayo Clinic who wasn't part of the panel.
The Institute of Medicine, which advises the U.S. and Canadian governments, recommends about 1,000 mg of calcium, 1,300 for postmenopausal women, every day. For vitamin D, the goal is 600 IUs of vitamin D every day, increasing to 800 after age 70.
Kholsa said most people should get enough calcium from foods including:
- Orange juice fortified with calcium and D.
- Milk, yogurt and cheese.
- Certain fish including salmon.
- Fortified breakfast cereals.
Physical activity is also recommended for bone health.
The task force is still studying vitamin D's potential to prevent cancer. So far, the observational evidence strongest for vitamin D reducing colorectal cancer but the proof is weak or inconsistent for cancer overall and breast and prostate tumours, according to the Endocrine Society.