Effects of high ß-glucan barley on visceral fat obesity in Japanese individuals: A randomized, double-blind study.

OBJECTIVE: The aim of this study was to investigate whether a diet in which high ß-glucan barley was substituted for rice would reduce visceral fat obesity in Japanese individuals. METHODS: A randomized, double-blind, placebo-controlled intervention study was conducted with 100 Japanese individuals with waist circumference (WC) ≥85 cm for men or ≥90 cm for women and body mass index (BMI) ≥24 kg/m2. Participants were randomly assigned to consume a mixture of rice and either high ß-glucan barley (test group, 4.4 g/d) or ß-glucan-free barley (placebo group) for 12 wk. Blood samples and computed tomography scans were obtained before and after the trial. RESULTS: Both groups showed decreases in body weight and BMI, and these changes were significantly greater in the test group. WC and visceral fat area (VFA) significantly decreased in both groups (VFA: -10.7 cm2 in the test group; -6.8 cm2 in the placebo group). These changes did not differ significantly between the groups. However, a subgroup analysis of participants with VFA ≥100 cm2 showed a significant decrease in the test group, and this decrease was significantly greater than in the placebo group. CONCLUSIONS: The intake of high ß-glucan barley led to significant and safe reductions in VFA, body weight, BMI, and WC in individuals with visceral fat obesity with VFA ≥100 cm2. Barley high in ß-glucan may contribute to preventing visceral fat obesity.

Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation.

Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs) can regulate secondary wall formation in rice (Oryza sativa) and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S) has very low transcriptional activation ability, but the longer protein (OsSWN2L) and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions) due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.