A newly released study in The Journal of Nutrition shows that milk calcium and calcium carbonate supplementation are equally effective in the acute suppression of bone breakdown in postmenopausal women irrespective of visceral fat.
Although obesity is often thought to have a favorable effect on bone health, more recent findings suggest that bone quality is compromised in obese people, particularly in postmenopausal women with central adiposity. Postmenopausal females with higher visceral adipose tissue have reduced C-terminal crosslinking telopeptide of type 1 collagen (a biomarker used to measure bone turnover) and osteocalcin (a hormone that plays a role in bone mineralization) and elevated parathyroid hormone compared to females with lower visceral adipose tissue. Chronically elevated parathyroid hormone can alter calcium metabolism and increase inflammation, which can negatively impact bone health. The extent to which obesity alters the effects of calcium intake on bone metabolism remains unclear. Whether calcium requirements should be adjusted based on body composition has not yet been systematically investigated.
To bridge this knowledge gap, Deepti Sharma (University of South Australia) and colleagues compared the acute effects of 2 calcium sources (dietary calcium and calcium carbonate) on biomarkers of bone breakdown and parathyroid suppression in lean and overweight postmenopausal women. In a randomized three period crossover trial conducted between 2017 and 2019 among 77 lean and overweight postmenopausal women, participants received a single dose of milk (1000 mg calcium), calcium carbonate tablet (1000 mg calcium), and fruit juice (no calcium) in random order with a 7-day washout period. Blood samples were collected at baseline and hourly for 5 hours.
At baseline, women with higher visceral adipose tissue had significantly higher measures of bone turnover and higher levels of parathyroid hormone, between quintiles 4 and 1. Visceral adipose tissue had no influence on acute changes in bone turnover or parathyroid hormone with calcium or juice. Both milk calcium and calcium carbonate at 1000 mg acutely suppressed bone turnover up to 5 hours after ingestion. A suppression of 44% in bone turnover was seen with calcium carbonate and milk and a suppression of 18% with juice. Parathyroid hormone was suppressed more with calcium carbonate (47%) compared to milk (22%). These findings suggest that the intake of 1000 mg of calcium from milk or from calcium carbonate is effective in acutely suppressing bone turnover in postmenopausal women irrespective of visceral adipose tissue.
In a companion commentary, Jay Cao (Grand Forks Human Nutrition Research Center, United States Department of Agriculture) comments that findings from this and other studies suggest that calcium supplementation strategies, including optimizing the time of day of calcium intake, should be explored for improving bone health in obese, postmenopausal women.
Deepti K Sharma, Paul H Anderson, Howard A Morris, Peter M Clifton, Acute C-Terminal Crosslinking Telopeptide of Type I Collagen (CTX-1) Suppression with Milk Calcium or Calcium Carbonate Is Independent of Visceral Fat in a Randomized Crossover Study in Lean and Overweight Postmenopausal Women, The Journal of Nutrition, Volume 152, Issue 4, April 2022, Pages 1006–1014, https://doi.org/10.1093/jn/nxab384.
Jay J Cao, Calcium Consumption Is Beneficial to Bone Health in Postmenopausal Women with Obesity, The Journal of Nutrition, Volume 152, Issue 4, April 2022, Pages 922–923, https://doi.org/10.1093/jn/nxac008.
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