Obesity and calcium: Study to assess body composition and osteoporosis risk

By Gary Scattergood

- Last updated on GMT

It is not known whether the recommended level or source of calcium should be adjusted depending on body composition. ©iStock
It is not known whether the recommended level or source of calcium should be adjusted depending on body composition. ©iStock

Related tags Osteoporosis Vitamin d

An Australian trial is recruiting 120 post-menopausal women — both lean and overweight — to investigate how a person's body composition influences the effect of calcium against bone loss.

University of South Australia PhD candidate Deepti Sharma wants to assess if body fat protects against osteoporosis or makes people more vulnerable to bone fractures.

Osteoporosis affects one million Australians who suffer from poor bone density and altered bone quality — and this number is expected to increase as the country's population ages.

"We know how much daily calcium someone needs to consume to help protect against osteoporotic fractures later in life. However, it is not known whether the recommended level or source of calcium should be adjusted depending on someone's body composition,"​ said Sharma. 

"People who are obese may have poor quality bones and may need to adjust their source of calcium to account for this."

The trials form the second stage of Sharma's PhD thesis, which also looks at the role of vitamin D in protecting bone health. She has recruited more than 100 patients undergoing hip replacement surgery due to fractured hips, and analysed their bones for structure, gene expression and measured blood biochemical profile. 

"What we have found is that high levels of vitamin D in the blood are associated with improved bone structure.

"We have known for some time that people who have higher vitamin D levels have reduced fractures. Now we are showing that vitamin D is linked with improved activity in the bone and better quality of bone. This is something which we have not previously been able to see using standard bone mineral density tests,"​ she revealed. 

Fracture healing

Sharma's supervisor, Associate Professor Paul Anderson, says the findings could change clinical practices. 

"Our findings not only suggest that vitamin D and calcium are essential to prevent fractures, but also that both may help improve fracture healing,"​ Anderson said.

"We now know that even if you are in your 80s, if you have high levels of vitamin D, you can improve the quality of your bones."

Published data shows that up to 58% of southern Australian women are vitamin D-deficient during winter due to a lack of sun exposure. Even during summer, 42% of women are vitamin D-deficient due to lifestyle factors such as avoidance of the sun and the use of sunscreen protection. 

Anderson said most people need to expose their face and arms to some direct sunlight when the sun is high in the sky so that the body can produce vitamin D naturally. 

"If you are deficient in vitamin D, then taking a supplement is a safe and effective way to restore vitamin D levels.​ But when it comes to osteoporosis, it's not just about getting enough vitamin D and calcium,"​ he said.

"Low-intensity, frequent, weight-bearing exercise is also crucial for optimal bone health."

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