Effects of brown rice on cellular growth and metabolic changes in mice

The consumption of rice, especially brown rice, is known to promote cellular growth but the underlying mechanisms and key metabolites of this process are unclear. This study investigated the effects of brown rice on cellular growth and the underlying mechanisms using a metabolomics approach in vivo. C57BL/6J male mice were fed an isocaloric diet composed of control chow, Ilpum rice (IP; Oryza sativa L. cv. Ilpum), or Ilpum brown rice (IB) for 4 weeks, and then the metabolites of the liver were analyzed. The rice consumption reduced the liver enzyme levels in plasma and did not result in obesity. The plasma total-cholesterol levels were significantly reduced in the IB group compared with the IP group. The plasma concentrations of growth hormone and insulin growth factor-1 were significantly increased, along with increased thigh bone width in the IB group compared with the IP group, suggesting that the intake of brown rice promoted animal growth. Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) was used for the metabolic profiling of liver samples obtained from IP- and IB-fed mice. The obtained data sets were subjected to multivariate statistical analysis to investigate which metabolites contributed to the differences between the IP and IB groups. GC-TOF-MS analysis revealed the presence of 31 metabolites consisting of 8 lipids, 4 sugars and sugar alcohols, 15 amino acids, and 4 organic acids. Partial least-squares regression analysis demonstrated significant correlations between the data collected from GC-TOF-MS and the levels of growth hormone. The levels of l-valine, l-glutamine, and d-mannose were significantly higher in the IB group than the control and IP groups.