A high dairy protein, high-calcium diet minimizes bone turnover in overweight adults during weight loss.
Weight loss induces bone resorption and this can be attenuated by calcium supplementation. Protein-rich diets were recently associated with favorable effects on bone density, although this remains controversial. We hypothesized that a diet high in calcium and protein would minimize bone resorption during weight loss compared with a lower calcium, protein-rich diet. The effects of dietary calcium in high protein diets on calcium excretion and bone metabolism were examined in overweight adults (n = 50, BMI 33.4 +/- 2.1 kg/m(2)) during 12 wk of energy restriction followed by 4 wk of energy balance. Subjects were randomly assigned to isoenergetic diets (5.5 MJ/d, 34% energy from protein, 41% carbohydrate, 24% fat) high in either dairy protein (DP, 2400 mg Ca/d) or mixed protein sources (MP, 500 mg Ca/d). During energy restriction, weight loss was 10% (-9.7 +/- 3.8 kg, P < 0.01), and 24-h urinary calcium excretion decreased independently of diet (-1.09 +/- 0.23 mmol/d, P < 0.01). By wk 16, the MP diet group had a 40% greater increase in deoxypyridinoline (bone resorption marker) than the DP diet group (P = 0.008). Osteocalcin (bone formation marker) increased from wk 0 to 16 in only the MP diet group [+2.16 +/- 0.63 micro g/L (+0.63 +/- 0.11nmol/L), P = 0.001]. In conclusion, weight loss was associated with increased bone resorption, yet the DP diet had a modest advantage over the MP diet by minimizing overall turnover. Combined with reduced urinary calcium excretion, this suggests that a high-protein, calcium-replete diet may protect against bone loss during weight reduction.
Bowen
Jane
J
CSIRO Health Sciences and Nutrition, Adelaide, South Australia, Australia, 5000.
Noakes
Manny
M
Clifton
Peter M
PM
D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D001862:Bone Resorption / Q000517:prevention & control*; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000652:urine; D002136:Calcium, Dietary; D003611:Dairy Products; D004038:Diet, Reducing; D004044:Dietary Proteins; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity; D015431:Weight Loss
D002136:Calcium, Dietary; D004044:Dietary Proteins; D002118:Calcium