Incorporation of Whole or Milled Dry Edible Beans into a High-Fat Diet Improves Bone Structure in Obese Mice

Abstract

Background

Pulses, a healthy diet component, have many bone-beneficial nutrients.

Objectives

This study investigated whether incorporation of dried pulses to a high-fat diet improves bone metabolism in obese mice.

Methods

Male C57BL/6 mice at 4-wk-old were randomly assigned to 4 diet groups (n = 22–24/group) for 12 wk: a normal-fat (NF; 4.1 kcal/g and 16% energy as fat), a HF (4.9 kcal/g and 48% energy as fat), or a HF containing either whole beans (HFWB) or milled bean flour (HFMB) at 15% wt/wt. Diets containing beans had similar total energy, protein, and fiber content as the HF without beans. Bone structure and related biomarkers were measured. Data were analyzed using a 1-way analysis of variance followed by Tukey-Kramer post hoc contrasts.

Results

Mice fed the HFWB or HFMB but not the HF had higher lean mass than those fed the NF (P < 0.05, 9.1% and 8.7%, for HFWB and HFMB, respectively). Mice fed the HF, HFWB, or HFMB had 23%, 14%, and 12% lower tibial bone volume/total volume (P < 0.05), respectively, than those on the NF. Mice fed the HF but not the HFWB or HFMB had 9.2% lower bone volume/total volume in the second lumbar vertebrae than those fed the NF (P < 0.05). Pooled HF with bean groups had 18%, 14%, 27%, 17%, and 15% greater body weight, fat mass, plasma concentrations of tartrate-resistant acid phosphatase, C-terminal telopeptide of type 1 collagen, blood glucose than the HF alone, respectively (P < 0.05). Milled bean flour had a greater impact on body weight, fat mass, tibial structural model index, circulating leptin, and glucose than whole bean relative to the HF alone.

Conclusions

These data indicate that the incorporation of dry edible beans into a HF mitigates but does not fully prevent bone deterioration in obese mice.