Barley, whether whole grain or pearl, has equal function and suppresses obesity


【Introduction】
The authors confirmed the visceral fat-reducing effect of barley rice in a previous study (see "Confirmation of the visceral fat-reducing effect of beta-glucan contained in barley rice"). However, because the amount of barley in the test and control diets differed, the content of components other than β-glucan in the barley was also different. Thus, an animal study was conducted to confirm that the visceral fat reduction effect was due to β-glucan.

【Materials and Methods】
4Four-week-old male mice (C57BL/6J) were divided into four groups (10 mice per group) and kept for 12 weeks with ad libitum intake of high-fat food containing the following. The total amount of dietary fiber in each group was matched at 5% of the diet by the addition of cellulose.
・The whole grains of the β-glucan-rich barley, Beau Fiber: BF-W
・60% pearled flour of the β-glucan-rich barley, Beau Fiber (Note): BF-P
・The whole grain flour of β-glucan-free barley, Shikoku-hadaka 84(bgl): BGL-W
・60% pearled flour β-glucan-free barley, Shikoku-hadaka 84(bgl): BGL-P
An oral glucose tolerance test (OGTT) was performed at 11 weeks after 6 hours of fasting. Fecal samples were collected two days before dissection and sequenced to examine the gut microbiome. At the end of the study period, the animals were dissected after 7 hours of fasting. The composition and weight of adipose tissue and liver were analyzed, and blood tests were performed.

【Results】
There was no difference in food intake or body weight between the four groups; the two BF groups had significantly lighter mesenteric fat weight and significantly heavier cecum weight than the two BGL groups. In the blood glucose tolerance test, the two BF groups had significantly lower blood glucose levels, the area under the blood glucose curve, and insulin secretion after 15 to 120 minutes than the two BGL groups. None of the results were significantly different between the whole grain and pounded flour groups.

LDL-cholesterol and blood glucose levels were significantly lower in the two BF groups. HDL-cholesterol, triglyceride, free fatty acid, and HbA1c levels were not significantly different between the two groups.

Lipid accumulation in the liver was also not significantly different between the whole grain and pearled flour groups. Triglyceride and cholesterol levels were significantly lower in the two BF groups.

Analysis of the intestinal microbiome showed that the ratio of Clostridium was significantly lower in the two BF groups, and the ratios of Bifidobacterium, Lactobacillus, and Prevotella were significantly higher.

Examination of the expression of inflammatory system markers in epididymal fat showed no significant difference between the whole grain and pearled flour groups. The F4/80 and TNF-α were significantly lower in the two BF groups.

【Discussion and Conclusion】
The high-fat diet containing high-β-glucan barley reduced visceral fat and total cholesterol levels, fat accumulation in the liver, and inflammatory system markers in mice compared with containing β-glucan-free barley. The improvement of postprandial glycemic response by β-glucan seems to be one of the factors that suppress obesity. It was also found that various parameters related to obesity did not differ between whole and pearled flours.

The significantly heavier cecum weight in the two BF groups, a lower ratio of Clostridium, and a higher ratio of Bifidobacterium may be due to changes in the intestinal microbiome caused by intestinal fermentation of β-glucan. A recent study has shown that obese people have more bacteria from the Firmicutes (Clostridium cluster subgroups) and fewer bacteria from the Bifidobacterium phylum.

【Research institution】
Otsuma Women's University
National Agriculture and Food Research Organization (NARO)
Western Region Agricultural Research Center

(Note) Whole grain barley is pounded 40%, and the rest is ground into flour.

EEffects of β-glucan content and pearling of barley in diet-induced obese mice
Cereal chemistry 27 Sep 2017