The protein source determines the potential of high protein diets to attenuate obesity development in C57BL/6J mice

abstract

The notion that the obesogenic potential of high fat diets in rodents is attenuated when the protein:carbohydrate ratio is increased is largely based on studies using casein or whey as the protein source. We fed C57BL/6J mice high fat-high protein diets using casein, soy, cod, beef, chicken or pork as protein sources. Casein stood out as the most efficient in preventing weight gain and accretion of adipose mass. By contrast, mice fed diets based on pork or chicken, and to a lesser extent mice fed cod or beef protein, had increased adipose tissue mass gain relative to casein fed mice. Decreasing the protein:carbohydrate ratio in diets with casein or pork as protein sources led to accentuated fat mass accumulation. Pork fed mice were more obese than casein fed mice, and relative to casein, the pork-based feed induced substantial accumulation of fat in classic interscapular brown adipose tissue accompanied by decreased UCP1 expression. Furthermore, intake of a low fat diet with casein, but not pork, as a protein source reversed diet-induced obesity. Compared to pork, casein seems unique in maintaining the classical brown morphology in interscapular brown adipose tissue with high UCP1 expression. This was accompanied by increased expression of genes involved in a futile cycling of fatty acids. Our results demonstrate that intake of high protein diets based on other protein sources may not have similar effects, and hence, the obesity protective effect of high protein diets is clearly modulated by protein source.

Keywords::

• adiposity
• animal models
• brown adipose tissue
• diet
• protein sources

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Funding

This project was supported by the European Union FP7 project DIABAT (HEALTH-F2–2011–278373) to J.B.H., K.K. and L.M. This work was also in part supported by The Carlsberg Foundation, The Norwegian Seafood Research Fund (FINS 900842), the Norwegian Research Council (200515/ I30), the SHARE Cross Faculty Ph.D. Initiative of the University of Copenhagen and NIFES.

Acknowledgments

We thank Dr. Pavel Flachs and Prof. Jan Kopecky for kindly providing the UCP1 antibody used for immunohistochemistry and the staff at NIFES for technical assistance and animal care. We would like to specifically acknowledge the early contribution of Vigdis Misje Hagen to this project.

Authors`contributions

B.L., K.K. and L.M. designed research. U.L., L.S.M., A.K.R., E.F., S.B., K.R.F., A.L.B. and J.B.H. performed experiments and all authors interpreted the results. U.L., L.S.M, KK and L.M. wrote the manuscript. U.L., L.S.M. and E.F. prepared the figures. All authors edited and revised the manuscript and approved the final version. K.K. and L.M. have primary responsibility for the final content.