Effects of the brown rice diet on visceral obesity and endothelial function: the BRAVO study.

Brown rice (BR) and white rice (WR) produce different glycaemic responses and their consumption may affect the dietary management of obesity. In the present study, the effects of BR and WR on abdominal fat distribution, metabolic parameters and endothelial function were evaluated in subjects with the metabolic syndrome in a randomised cross-over fashion. In study 1, acute postprandial metabolic parameters and flow- and nitroglycerine-mediated dilation (FMD and NMD) of the brachial artery were determined in male volunteers with or without the metabolic syndrome after ingestion of either BR or WR. The increases in glucose and insulin AUC were lower after ingestion of BR than after ingestion of WR (P= 0·041 and P= 0·045, respectively). FMD values were decreased 60 min after ingestion of WR (P= 0·037 v. baseline), but the decrease was protected after ingestion of BR. In study 2, a separate cohort of male volunteers (n 27) with the metabolic syndrome was randomised into two groups with different BR and WR consumption patterns. The values of weight-based parameters were decreased after consumption of BR for 8 weeks, but returned to baseline values after a WR consumption period. Insulin resistance and total cholesterol and LDL-cholesterol levels were reduced after consumption of BR. In conclusion, consumption of BR may be beneficial, partly owing to the lowering of glycaemic response, and may protect postprandial endothelial function in subjects with the metabolic syndrome. Long-term beneficial effects of BR on metabolic parameters and endothelial function were also observed.

Ectopic fat deposition and global cardiometabolic risk: new paradigm in cardiovascular medicine.

The obesity epidemic is a global public health concern that increases the likelihood of morbidity and mortality of metabolic and cardiovascular disease (CVD) and threatens to reduce life expectancy around the world. The concept of the metabolic syndrome (MetS) takes into account that visceral fat plays an essential role in the development of metabolic and cardiovascular diseases. However, MetS cannot be used to assess global CVD risk but is at best one more modifiable CVD risk factor. Thus, global cardiometabolic risk (the global risk of cardiovascular disease resulting from traditional risk factors combined with the additional contribution of the metabolic syndrome and/or insulin resistance) should be considered individually. There is solid evidence supporting the notion that excess abdominal fat is predictive of insulin resistance and the presence of related metabolic abnormalities currently referred to as MetS. Despite the fact that abdominal obesity is a highly prevalent feature of MetS, the mechanisms by which abdominal obesity is causally related to MetS are not fully elucidated. Besides visceral fat accumulation, ectopic lipid deposition, especially in liver and skeletal muscle, has been implicated in the pathophysiology of diabetes, insulin resistance and obesity-related disorders. Also, ectopic fat deposition could be deteriorated in the heart components such as (1) circulatory and locally recruited fat, (2) intra- and extra-myocellular fat, (3) perivascular fat, and (4) pericardial fat. In this review, the contribution of ectopic lipid deposition to global cardiometabolic risk is reviewed and also discussed are potential underlying mechanisms including adipocytokine, insulin resistance and lipotoxicity.

Lipid deposition in various sites of the skeletal muscles and liver exhibits a positive correlation with visceral fat accumulation in middle-aged Japanese men with metabolic syndrome.

Objective In addition to excess visceral fat, lipid deposition in the liver and skeletal muscle has been implicated in the pathophysiology of type 2 diabetes and metabolic syndrome. This study was designed to explore the relationship between hepatic and muscular lipid deposition and visceral fat accumulation in 105 middle-aged men with metabolic syndrome. Methods Abdominal computed tomography (CT) was used to simultaneously evaluate the visceral fat area (VFA) and CT Hounsfield unit (HU) values of three different portions of skeletal muscle and the liver. Results A significant inverse correlation was observed between the VFA and the CT HU values of the iliopsoas muscle, back muscle, rectus abdominis muscle and liver. Three types of interventions, i.e., lifestyle modification and treatment with antidiabetic drugs, such as Pioglitazone or Miglitol, caused significant decreases in visceral fat accumulation. The extent of lipid deposition in the liver was strongly correlated with the levels of glucose-lipid metabolic markers, which decreased significantly following Pioglitazone treatment. On the other hand, the amount of lipid deposition in the three skeletal muscles and the liver did not decrease after Miglitol treatment. Conclusion Visceral fat accumulation is accompanied by excess lipid deposition in skeletal muscle and the liver in patients with metabolic syndrome. The CT-based simultaneous, concise evaluations of ectopic lipid deposition and visceral fat mass used in the present study may provide unique information for assessing cardiometabolic risks and the therapeutic impact in patients with diabetes-obesity syndrome.

Brown rice and its component, γ-oryzanol, attenuate the preference for high-fat diet by decreasing hypothalamic endoplasmic reticulum stress in mice.

Brown rice is known to improve glucose intolerance and prevent the onset of diabetes. However, the underlying mechanisms remain obscure. In the current study, we investigated the effect of brown rice and its major component, γ-oryzanol (Orz), on feeding behavior and fuel homeostasis in mice. When mice were allowed free access to a brown rice-containing chow diet (CD) and a high-fat diet (HFD), they significantly preferred CD to HFD. To reduce hypothalamic endoplasmic reticulum (ER) stress on an HFD, mice were administered with 4-phenylbutyric acid, a chemical chaperone, which caused them to prefer the CD. Notably, oral administration of Orz, a mixture of major bioactive components in brown rice, also improved glucose intolerance and attenuated hypothalamic ER stress in mice fed the HFD. In murine primary neuronal cells, Orz attenuated the tunicamycin-induced ER stress. In luciferase reporter assays in human embryonic kidney 293 cells, Orz suppressed the activation of ER stress-responsive cis-acting elements and unfolded protein response element, suggesting that Orz acts as a chemical chaperone in viable cells. Collectively, the current study is the first demonstration that brown rice and Orz improve glucose metabolism, reduce hypothalamic ER stress, and, consequently, attenuate the preference for dietary fat in mice fed an HFD.