Increasing calcium intake does not reduce the risk of fractures or boost bone health and it's time for policymakers to revise dietary recommendations, according to two new studies published Tuesday in the British Medical Journal.
The researchers reviewed dozens of studies and found that, overall, more calcium did not result in lower fracture rates. In a separate study, they found that while people who consumed more calcium had slightly higher bone mineral density, the increases were too small to have any significant impact on overall bone health. The findings apply to dietary sources of calcium and to supplements, which have come under a cloud in recent years because of studies linking them to heart problems.
Despite this, the public continues to hear that more calcium is better because "many companies with vested interests" in sales of supplements and dairy products "sponsor influential organizations and academic opinion leaders," lead researcher Dr. Mark Bolland, associate professor in the School of Medicine at the University of Auckland in New Zealand, said in an e-mail.
Most adults consume between 700 and 900 milligrams of calcium a day, according to the studies. But official dietary guidelines in Canada urge people to consume more – between 1,000 and 1,300 milligrams, depending on their age. For instance, Health Canada advises children between ages nine and 18 to consume 1,300 milligrams a day and women over age 50 to consume 1,200 milligrams a day.
But according to the new research, most studies "did not report reduced risk of fracture in individuals with this level of calcium intake compared with lower intake." There were a few studies that suggested higher calcium intake was linked to a decreased risk of fracture. But the researchers used two tools that found high levels of bias in those reports.
This isn't the first time researchers have suggested revisiting calcium intake recommendations. But Bolland argues policymakers aren't listening because industry influence is too great.
In an analysis published in the British Medical Journal in July, Bolland and colleague Andrew Grey urge academic researchers, advocacy organizations and health associations to cut ties with the dairy and supplement industries to prevent the public from getting overstated messages about the importance of increasing calcium.
An editorial published Tuesday alongside the two new studies also suggests that conflicts of interest can arise as a result of industry relationships with academic and advocacy groups, which does a disservice to the public.
In Canada, there are numerous examples of partnerships or relationships between the dairy and supplement industry and researchers or health groups. On its website, for instance, Osteoporosis Canada thanks its two corporate partners: the Dairy Farmers of Canada and Caltrate, a maker of calcium and vitamin D supplements. Osteoporosis Canada did not respond to an interview request. The Dairy Farmers of Canada website contains a list of its partners, which include Dietitians of Canada, the Heart and Stroke Foundation, Osteoporosis Canada and the Canadian Nutrition Society.
Dr. Heather McKay, director of the Centre for Hip Health and Mobility at the Vancouver Coastal Health Research Centre agrees that calcium recommendations need to be changed. There is no good evidence supporting the idea more calcium is better and the public needs a better understanding of how to prevent fractures, said McKay, who was not involved with the two BMJ studies. Adequate calcium is necessary to maintain health, she said, but taking pains to increase those levels isn't going to help, she said. Falling is the biggest risk that leads to fractures, which is why exercise, building muscle strength and keeping mobile play a much greater role in reducing risks, she said.
"I think as a culture, unfortunately, we would rather take something than do something," said McKay, who is also a professor in the faculty of medicine at the University of British Columbia. "It's easy to prescribe calcium as opposed to prescribing exercise."