The Blood Glucose-lowering Effect And Mechanisms Of Foxtail Millet Intervention

Foxtail millet is the leading variety in China and it was first domesticated and selected as grain food in the Yellow River basin as early as 8700 years ago.China ranks first in the production of foxtail millet in the world.More than 400 years ago,the hypoglycemic effect of foxtail millet was first recorded in Traditional Chinese Medicine.Thus the aim of this study was investigate the blood glucose-lowering effect and mechanisms of foxtail millet intervention,with the combination methods of traditional nutrition,clinical nutrition,gut microbiota and transcriptomics.First,3 kinds of pure foxtail millet products were produced and the in vitro starch digestibilities and in vivo glycemic indices(GI)of foxtail millet and pure millet products were investigated.The in vitro results showed that starch digestibility of foxtail millet flour is obviously lower than that of wheat flour.However,deproteinization and heating significantly increased its rapidly digestible starch and decreased its slowly digestible starch and resistant starch.Then the in vitro starch digestibilities and in vivo glycemic indices(GI)of 5 kinds of foxtail millet-derived products were investigated.The GIs of pure millet products were in the following order:millet porridge(93.6 ± 11.3)>millet steamed bread(89.6±8.8)>No.1 millet pancake(75.0%millet flour and 25.0%extrusion flour,83.0 ± 9.6)>No.2 millet pancake(without extrusion flour,83.0± 9.6)>cooked millet(64.4± 8.5).They were significantly positively correlated with the rapidly digestible starch(r=0.959),degree of gelatinization(r=0.967)and estimated glycemic index(r=0.988).Considering the feasibility and consistency of dietary intervention,3 kinds of foxtail millet-derived products were frozen stored at-18? or-40? and the effects of the freezing process,frozen storage temperature and frozen storage time on starch digestion characteristics were investigated.The first week,especially the first day of frozen storage,had a greater effect on starch digestibility,as compared to the rest days of frozen storage.Thus the frozen stored products are available for a 12 weeks of foxtail millet intervention.Weather the long term consumption of foxtail millet could improve the glycemic control steadily?We investigated the effect of foxtail millet on blood glucose metabolism in high fat diet and STZ-induced diabetic rats.The results shown that,foxtail millet diet significantly decreased the fasting blood glucose and significantly increased the insulin sensitivity in high fat diet and STZ-induced diabetic rats.The hypoglycemic effect was similar to metformin which was the clinical choice for hypoglycemic daugs.But no obvious increases in blood insulin concentration and islet ?-cell number were observed.There is no animal model which can copy all the characteristics of human disease.Therefore,a 12 weeks of foxtail millet intervention,instead of the corresponding amount of staple foods,was conducted in 64 subjects with impaired glucose tolerance(IGT).The intake of 50 g of foxtail millet per day significantly decreased the fasting blood glucose(5.74 ± 0.12 at week 0 vs 5.30± 0.09 at week 12),2 h-glucose after oral glucose tolerance test(10.21±0.33 at week 0 vs 9.36 ± 0.28 at week 12),HOMA-IR(4.16± 0.33 at week 0 vs 3.34 ± 0.25 at week 12)and obesity degree and significantly increased the leptin concentration among subjects with IGT,without significant difference in nutriment consumption,physical activity level and other lifestyle factors.The intake of foxtail millet also improved of blood lipid and pressure,kidney function,bone density,sleep quality and body inflammation.In addition,the intake of 50 g of foxtail millet per day significantly increased the species richness of gut microbiota and the relative abundance of Faecalibacterium(14.42 ± 1.37%vs 19.99 ± 1.25%).Based on the above research,we can confirmed the blood glucose-lowering effect of foxtail millet intervention.But how does it work?To clarify the mechanisms of the hypoglycemic effect of foxtail millet,the effect of foxtail millet on gut microbiota and transcriptomics in high fat diet and STZ-induced diabetic rats were investigated.The results shown that,foxtail millet diet significantly increased the relative abundance of Lactobacillus and Ruminococcus,significantly decreased the relative abundance of Blautia?Allobaculum and Lachnospiraceae.4 weeks of foxtail millet feeding in this study could mitigate negative variations of gut microbiota and liver transcriptional profile in HFD/STZ diabetic rats.On the one hand,foxtail millet intervention may improve blood glucose metabolism by inhibiting gluconeogenesis,stimulating glycolysis and repair fatty acid synthesis through insulin-stimulated PI3K/AKT signaling pathway.On the other hand,foxtail millet intervention may improve blood glucose metabolism by inhibiting NF-?B signaling pathway and reducing expression of inflammatory factors,which can stimulate the activation of insulin signaling pathway.