Flavonoids are a subgroup of polyphenols that are present in plants as secondary metabolites. Flavonoids are bioavailable in humans and provide a number of health benefits including protection from cancer and cardiovascular disease. This protection likely stems from the ability of flavonoids to act as antioxidants in combination with their ability to regulate specific genes. Health benefits from flavonoids may also come from their ability to facilitate weight loss. One way this can be achieved is in their ability to improve the health of the liver. For example, citrus flavonoids including naringenin, hesperetin, nobiletin, and tangeretin may improve insulin sensitivity, reduce dyslipidaemia and improve hepatic steatosis through an ability to favourably regulate hepatic lipid metabolism. Their ability to downregulate inflammation may be pivotal in this activity, as aberrant lipid metabolism in the liver is associated with a significant inflammatory component. Naringenin in the aglycone form of the glycoside form naringin found in citrus fruit, and evidence supports a role for it in the regulation of gene expression. For example it may inhibit adipose differentiation and may alter gene expression of a number of genes associated with fatty acid oxidation including uncoupling protein 1. Flavan-3-ols from plants including tea and cocoa may also increase metabolic activity and are associated with fat loss. Tea flavan-3-ols form a group called the catechins, and these polyphenolic compounds have been shown to induce fat loss and lead to increased fat oxidation in animal models. Flavan-3-ols may also upregulate genes associated with thermogenesis including uncoupling proteins 1 and 3.
Eat Well, Stay Healthy, Protect Yourself
RdB
Stohs, S. J. and Badmaev, V. 2016. A review of natural stimulant and non‐stimulant thermogenic agents. Phytotherapy Research. 30(5): 732-740
Caffeine is found in a number of foods, most notably tea and coffee. Caffeine is widely consumed and it is almost ubiquitous in the diet of the population of the world. Caffeine is a central nervous system stimulant that is thought to inhibit the phosphodiesterase enzyme which can potentiate the activity of cellular cAMP. As cAMP is involved in the regulation of cell function, including potentiating the cellular effects of adrenaline, caffeine can have a significant stimulatory effect. Caffeine also targets the adenosine receptor by binding to adenosine A1 and adenosine A2a receptors. Inhibition of the adenosine A1 receptor activates adenylate cyclase, which causes the generation of cellular levels of cAMP and protein kinase A, and these mechanisms cause stimulation of the central nervous system. Caffeine causes an increase in energy metabolism and this can make it a useful weight loss substance. Caffeine can also affect muscle tissue, and part of this is a chronotropic effect, whilst part of this is an inotropic effect. The chronotropic and inotropic effects of caffeine make it a useful substance for improving athletic performance. Caffeine is also a diuretic and can cause vasodilation and relaxation of smooth muscle.