Calcium, Bones, and Fractures

As Amy Campbell noted in her blog here at DiabetesSelfManagement.com several years ago, osteoporosis — the development of less dense, porous bones that are more prone to fracture — is a possible complication of diabetes that is often forgotten. According to the National Institutes of Health, people with Type 1 diabetes tend to have less dense bones and are therefore at greater risk for osteoporosis and fractures. People with Type 2 diabetes, on the other hand, tend to have denser bones than similar people without diabetes. But despite this higher density, Type 2 diabetes still puts you at greater risk for fractures — possibly because certain diabetes complications can affect your balance and make you more likely to fall. No matter what type of diabetes you have, you should pay extra attention to your bones and risk of fractures.

So two recent studies questioning the benefits of calcium supplements may come as a shock to many people with diabetes. Both studies were published late last month in the medical journal BMJ and were reviews of previous research. The first study looked at the relationship between calcium intake and risk of bone fracture. According to a HealthDay article on both studies, in the first study, researchers at the University of Auckland in New Zealand looked at 46 previous studies on the relationship between dietary calcium or dairy intake and bone fractures. The majority of studies found no correlation between calcium intake and risk of fracture. The researchers also looked at 26 randomized controlled trials (the “gold standard” of study design) on calcium supplements and bone fractures. While most studies found that calcium supplements helped reduce fracture risk, the researchers found evidence that many studies were biased toward this outcome. In the studies with the fewest signs of bias, there was no association between calcium supplements and fracture risk.

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In the second study, researchers looked at 59 previous studies on the relationship between calcium intake and bone mineral density — an important predictor of future bone fractures. These studies looked at dietary calcium intake, calcium supplements, and calcium supplements paired with vitamin D. Overall, a higher calcium intake was found to result in a bone mineral density increase of between 0.6% and 1.8% — depending on the source of calcium, where on the body bone density was measured, and how much time had passed since the beginning of the study. Such a small increase, however, is unlikely to have any meaningful impact on a person’s risk of fractures. Furthermore, the researchers noted that calcium supplements often cause mild digestive side effects like constipation, and carry a small risk of severe side effects like kidney stones, heart attacks, high blood calcium levels, and acute gastrointestinal symptoms that require hospitalization.

What’s your take on these studies — are you surprised that they found no relationship between dietary calcium intake and risk of bone fractures? Do you feel like the small increase in bone density caused by calcium supplements is good enough reason to take them, even if calcium supplements can also cause side effects? Would you be more comfortable increasing your dietary intake of calcium through foods like dairy products, leafy dark green vegetables, and canned fish with bones, rather than taking calcium supplements? Leave a comment below!

  • M. Aske

    yes, I would rather get my calcium from food rather than the supplements when their are so many side effects ffrom the supplements and it didn’t show much advantage in preventing bone fractures in older people.