Lipid profile, obesity and bone mineral density: the Hertfordshire Cohort Study.
BACKGROUND
Body mass index (BMI) and bone mineral density (BMD) are positively correlated in several studies, but few data relate bone density, lipid profile and anthropometric measures.


AIM
To investigate these relationships in a large, well-characterized cohort of men and women (The Hertfordshire Cohort Study).


METHODS
Men (n = 465) and women (n = 448) from Hertfordshire, UK were recruited. Information was available on demographic and lifestyle factors, anthropometric measurements, body fat percentage, fasting triglycerides, cholesterol (total, HDL, LDL), apolipoprotein (a) and apolipoprotein (b); bone mineral density (BMD) was recorded at the lumbar spine and total femur.


RESULTS
BMD at the lumbar spine (males r = 0.15, p = 0.001; females r = 0.14, p = 0.003) and total femoral region (males r = 0.18, p = 0.0001; females r = 0.16, p = 0.0008) was related to serum triglyceride level, even after adjustment for waist-hip ratio, age, social class and lifestyle factors, but not if body fat percentage was substituted for waist-hip ratio in the regression model. Fasting HDL cholesterol level was related to lumbar spine BMD in women (r = -0.15, p = 0.001) and total femoral BMD in both sexes (males r = -0.15, p = 0.002; females r = -0.23, p < 0.0001); these relationships were also attenuated by adjustment for body fat percentage but not waist-hip ratio. No relationships were seen between total or LDL cholesterol with BMD.


DISCUSSION
In this cohort, relationships between lipid profile and BMD were robust to adjustment for one measure of central obesity (waist-hip ratio), but not total body fat. This broadly supports the idea that adiposity may confound the relationship between lipids and bone mass.