Beneficial effects of green tea (Camellia sinensis, Theaceae) extracts against obesity have been reported; however, the anti-obesity ability of the major components of green tea, polysaccharides, polyphenols and caffeine is not clear. Therefore, experiments with total green tea extracts, polyphenols, polysaccharides, caffeine, and a complex of polysaccharide and polyphenol at a dose of 400 or 800 mg kg⁻¹ were conducted on high-fat diet fed rats for 6 weeks to investigate their anti-obesity effects. The results indicated that polyphenols and polysaccharides were responsible for the suppressive effect of green tea extracts on body weight increase and fat accumulation. Moreover, polyphenols, polysaccharides, or caffeine can improve blood lipid and antioxidant levels, and effectively reduce rat serum leptin levels, inhibit the absorption of fatty acids, and markedly reduce the expression levels of the IL-6 and TNF-α gene. Furthermore, it was shown that polysaccharides and polyphenols were synergistic in reduction of serum leptin levels and in anti-inflammatory activity. These results suggest that the polysaccharide combination with polyphenols might be a potential therapy against obesity.

This study was aimed at understanding potential mechanisms regarding bilberry anthocyanin extract consumption and healthy aging and the effects on intestinal barrier function and digestive enzyme activity, through regulating the gut microbiota in aging rats. Medium-dose bilberry anthocyanin extract consumption (20 mg per kg bw per day) was the optimum amount to regulate the intestinal function of aging rats. After consumption, bacteria beneficial to the intestine (Aspergillus oryzae, Lactobacillus, Bacteroides, Clostridiaceae-1, the Bacteroidales-S24-7-group and the Lachnospiraceae_NK4A136_group) were induced to grow, and harmful bacteria (Verrucomicrobia and Euryarchaeota) were inhibited. However, high-dose bilberry anthocyanin extract consumption altered some intestinally beneficial bacteria in an adverse way. There was a correlation between changes in bacterial composition and changes in short-chain fatty acids and the intestinal mucosal barrier. Bilberry anthocyanin extract consumption also decreased the activity of digestive enzymes. Our results suggest that bilberry anthocyanin extract consumption is a potential approach for assisting healthy aging.