A review article published in the journal Current Research in Food Science describes the anti-obesity modes of action of bioactive compounds present in coffee, tea, and cocoa.
Study: Coffee, tea, and cocoa in obesity prevention: mechanisms of action and future prospects. Image Credit: SAG stock / Shutterstock
Background
Obesity has become a significant public health concern worldwide owing to its gradually increasing prevalence. Obesity is characterized by excess body fat accumulation due to altered lipid metabolism. The condition can potentially increase the risk of various health complications, including cardiovascular disease, diabetes, dyslipidemia, hypertension, atherosclerosis, and inflammatory metabolic diseases.
Pharmaceuticals used for treating obesity, including mitochondrial uncouplers, sympathomimetics, serotonergic agonists, lipase inhibitors, cannabinoid receptor antagonists, and gastrointestinal-derived peptides, often fail to provide optimal benefits and are associated with many detrimental side effects.
Coffee, tea, and cocoa are the most widely used plant-derived beverages with potential anti-obesity effects. Several studies have highlighted the effectiveness of bioactive compounds present in these beverages in preventing obesity.
In this review article, authors have comprehensively analyzed 183 studies that investigated the effects and mode of action of coffee, tea, and cocoa in obesity management.
Coffee, tea, and cocoa in obesity management
Adipocytes, the primary cell type in adipose tissue, are responsible for body fat storage and metabolism regulation. White adipocytes store and mobilize triglycerides and secrete various lipid and protein factors to control energy balance.
Excessive adipogenesis and hypertrophy of white adipocytes are associated with obesity development. In contrast, the reactivation of brown and beige adipocytes provides metabolic health benefits and prevents obesity.
Thus, effective obesity management strategies should focus on inhibiting white adipocyte adipogenesis and promoting brown and beige adipocyte development and lipid catabolism (lipolysis).
Bioactive compounds present in functional foods like coffee, tea, and cocoa can inhibit white adipogenesis and promote brown adipogenesis and lipolysis, preventing obesity. While some compounds, including caffeine and chlorogenic acid (CGA), are present in all three beverages, some are specific to each type. Some of these specific compounds are trigonelline and cafestol in coffee, theaflavins and thearubigins in tea, and theobromine and quercetin in cocoa.
Coffee in obesity management
The major anti-obesity compounds present in green and roasted coffee include caffeine, CGAs, trigonelline, diterpenoids, cafestol, and kahweol.
Caffeine
Existing evidence indicates that caffeine can increase metabolic rate and promote fat tissue decomposition, resulting in reduced body weight. Caffeine can also increase fat oxidation during submaximal exercise.
Studies investigating the mode of action of caffeine find that it affects the AKT/GSK3β pathway and inhibits the expression of adipogenic proteins during adipocyte differentiation. Evidence also indicates that caffeine promotes thermogenesis by upregulating uncoupling proteins, increases lipolysis by increasing catecholamine secretion, inhibits lipogenesis, suppresses appetite, and reduces inflammatory responses.
Existing evidence on the health benefits of caffeine indicates that this bioactive compound is capable of preventing obesity, non-alcoholic fatty liver disease, and hepatosteatosis. Caffeine and epigallocatechin-3-gallate (EGCG) have been found to work synergistically to prevent obesity.
Chlorogenic acid
Studies investigating the mode of action of CGA find that the compound can improve body weight, lipid metabolism, and obesity-related hormone levels in mice consuming high-fat diets. CGA can inhibit fat accumulation by regulating the activities of enzymes related to hepatic lipid metabolism. CGA can promote brown adipogenesis by activating AMPK.
CGA and caffeine have synergistically promoted brown adipogenesis through the AMPK and PPARα/γ-mediated pathways. CGA has also been found to prevent obesity by modulating gut microbiota composition.
Trigonelline
Trigonelline has been found to prevent obesity by decreasing lipid levels, increasing the insulin sensitivity index and insulin content, upregulating antioxidant enzyme activity, and decreasing lipid peroxidation.
Mechanistic studies have shown that trigonelline promotes brown adipogenesis by stimulating p38 MAPK/ATF-2 signaling pathway. The compound has also been found to prevent white adipocyte differentiation and excessive white adipocyte hypertrophy.
Cafestol and kahweol
Cafestol has been found to exert anti-obesity effects by increasing fat oxidation and energy expenditure. Regarding kahweol, evidence indicates that the compound inhibits adipogenesis by activating the AMPK pathway.
Decaffarrolide B is an oxidation product of cafestol, which has been found to have a stronger adipogenesis-inhibiting effect than cafestol or kahweol.
Tea in obesity management
The compounds with anti-obesity activities in tea include catechins, L-theanine, theaflavin, thearubigin, and theabrownin.
Tea extracts have been found to prevent obesity by increasing brown adipogenesis, inhibiting white adipogenesis, increasing energy expenditure, and inhibiting lipid synthesis.
Mechanistic studies have found that Tea EGCG prevents adipogenesis by inducing cell cycle arrest in adipocytes. EGCG has been found to inhibit pancreatic lipase, salivary alpha-amylase, and starch digestion to reduce obesity-related metabolic factors.
Other anti-obesity modes of action of EGCG include increased fecal excretion of free fatty acids, inhibition of lipogenesis-related enzymes, and modulation of gut microbiota composition.
Another tea-derived compound, theaflavin has been found to improve glycolipid metabolism and obesity by activating the SIRT6/AMPK/SREBP-1/FAS signaling pathway. Further evidence indicates that the compound can prevent hepatic lipid accumulation by activating AMPK.
Other tea-derived compounds, including thearubigin, and theabrownin, have been found to exert anti-obesity activities by increasing drown adipogenesis, improving blood lipid profile, and reducing pro-inflammatory cytokines.
Cocoa in obesity management
Cocoa polyphenols, including flavanols (epicatechin, catechin, and procyanidins), flavonol (quercetin), anthocyanins, phenolic acids, and stilbenes, are known to have anti-obesity activities.
Cocoa polyphenols have been found to exert anti-obesity effects by increasing energy expenditure and thermogenesis, improving blood lipid profile, and reducing oxidative stress and inflammation.
Animal study findings have shown that cocoa extracts can reduce blood cholesterol levels, regulate glucose metabolism, and inhibit visceral adiposity. Peroxisome proliferator-activated receptors (PPARs), liver X receptors, adiponectin genes, and uncoupling proteins are the major targets of cocoa polyphenols in obesity management.
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