Effect of High Fat and Low Fat Diets on Bone Structure and Strength during Puberty

Abstract

Today nine million children in the United States are obese. Adolescent obesity rates at age 12 have tripled since 1980 and nutrition is a major contributor to this increase. Obesity-promoting diets and the widely circulating idea that increased body mass is a protective factor for bone is an area of research that deserves further exploration. PURPOSE: Determine the effect of a high fat or low fat diet during adolescence on bone strength and architecture. METHODS: Female Sprague-Dawley rats (N=31), 5 weeks of age, were divided into 2 groups and given High Fat (HF) and Low Fat (LF) diets. At sacrifice, week 11, right femurs were fixed and the trabecular region of the distal femur was scanned in an ex-vivo microCT scanner. Left femurs were mechanically tested using a three point bend assay. RESULTS: No differences were found in body weight between groups. There was a trend towards decreased mechanical strength in the LF group. Micro CT analysis revealed that percent bone volume was 19% (15.7/3.87 vs. 12.7/2.75, p < 0.05) greater in the HF compared to the LF group. Trabecular number was 14% greater (1.7610/.3215 vs 1.5123/.2568 1/mm, p < 0.05and trabecular thickness (.0886/.0700 vs.0833/.0057 mm p < 0.05) 6% greater in the HF group. A measure of architecture, the structural model index was 23% greater (.874/.202 vs 1.128/.224, rod- plate relationship, p < 0.05) in the LF group. CONCLUSIONS: The HF had a greater quantity of bone and an architecture that was more plate-like with no difference in body weight. This data along with the decreased bone strength in the LF group suggest that diet does impact the structure and strength of bone during puberty. The long-term consequences of these diets remain unknown. Supported by PSC-CUNY.