**4.4 Lipid-lowering effects**

Caffeine in tea can reduce the concentration of triglycerides in blood and catechin can inhibit lipid synthesis. The comprehensive effects of caffeine, catechin, tea polysaccharide, cholestenone, inositol, folic acid and pantothenic acid in tea can prevent and inhibit obesity. Studies have shown that the effect of jasmine scented tea on weight control may be related to its ability to increase lipoxin levels [64]. Consumption of jasmine scented tea can prevent elevated blood lipid levels and atherosclerosis, reduce the content of molecular substances in plasma and protect organs, such as the liver and kidneys. A study on rose scented tea found that its lipidlowering effect mainly comes from its high content of dietary fibre, rose flavonoids and various amino acids [67]. Rose scented tea is rich in dietary fibre, which cannot be converted to glucose in the human body, and has a low glycaemic index. It may be used as a common food for patients with diabetes. Dietary fibre can also combine with bile salts (metabolites of cholesterol), which are then excreted, effectively reducing the concentration of cholesterol in serum and further preventing and treating cardiovascular and cerebrovascular diseases. In addition, dietary fibre also promotes gastrointestinal motility, which can effectively prevent constipation and reduce the incidence of intestinal cancer. Lan et al. [68] examined the effects of rose extract on blood sugar and glucose tolerance in diabetic mice and found that both rose liquid extract and alcohol extract could effectively reduce blood sugar and improve glucose tolerance. A dose effect was seen and rose alcohol extract exerted a greater lipidlowering effect than rose water extract. A previous study evaluated the lipid-lowering effects of water-extracted flavonoids from honeysuckle and found that they significantly reduced plasma triglyceride and plasma cholesterol levels in hyperglycaemic mice [69]. The mechanisms involved changes in the transcription and expression levels of insulin receptor substrate 1, low density lipoprotein receptor, apolipoprotein 1, fatty acid synthase and cholesterol regulatory element binding protein 2 in the liver of the mouse model. These studies indicate that the polysaccharides, amino acids and flavonoids contained in jasmine, rose and honeysuckle have lipid-lowering effects and that these active substances are likely to have synergistic effects with the polyphenols in green tea in reducing blood lipids.
