With increasing levels of obesity, the low-carbohydrate diet has again become popular as a weight loss method. While weight loss through consumption of a low carbohydrate diet has been well researched, there is contradictory evidence regarding its effect on bone health. The effect of this diet on bone health for greater than 12 weeks and in menopausal women is relatively unknown. The aim of this study was to assess the effect of a low-carbohydrate diet consumed over 24 weeks on biomarkers of bone health in pre- and postmenopausal females. Following ethical approval, informed consent and screening, 24 subjects (13 pre-menopausal; 11 postmenopausal) were randomly assigned to a control or low-carbohydrate diet group for 24 weeks. Subjects were then crossed over to the alternative dietary regimen for 24 weeks. Blood and urine samples taken at week 12, 24, 36 and 48 were analysed for biomarkers of bone resorption and formation using ELIZA. Urine pH was measured and a 3 day food diary analysed using CompEat™. Data was analysed for treatment and carryover effects. Where carryover effects were evident analysis was completed on 12 subjects only. Consuming the low-carbohydrate diet resulted in a significant decrease in energy (P = 0.017) and carbohydrate (P = 0.001) but protein intake did not change (P = 0.264). There was a significant reduction in weight (P = 0.000), waist circumference (P = 0.000), diastolic blood pressure (P = 0.021), K (P = 0.047) and Mg (P = 0.005). Increased PRAL (P = 0.004), NTx (P = 0.019) and IGF-1 (P = 0.043) were observed in the low-carbohydrate period versus the control. Several other parameters changed over 12 weeks of the low-carbohydrate diet but not over the 24 week period. There were significant decreases in fibre, Ca and Na during the low carbohydrate diet over 12 weeks and increases in vitamin D and urinary Ca. There were no significant differences in any other parameters measured. Weight loss due to a low-carbohydrate diet caused significant changes in nutrient intake with some aspects being conducive to bone health but other aspects perhaps detrimental to bone. Increased bone resorption observed in this study without concomitant increased bone formation suggests this diet could cause poor bone health over time.
|Publication status||Unpublished - 2012|
- Bone health