Prebiotics are non-digestible food components able to modify host microbiota toward a healthy profile, concomitantly conferring general beneficial health effects. Numerous research works have provided wide evidence regarding the effects of prebiotics on the protection against different detrimental phenotypes related to cancer, immunity, and features of the metabolic syndrome, among others. Nonetheless, one topic less studied so far, but relevant, relates to the connection between prebiotics and energy metabolism regulation (and the prevention or treatment of obesity), especially by means of their impact on adaptive (non-shivering) thermogenesis in brown adipose tissue (BAT) and in the browning of white adipose tissue (WAT). In the present review, a key link between prebiotics and the regulation of adaptive thermogenesis and lipid metabolism (in both BAT and WAT) is proposed, thus connecting prebiotic consumption, microbiota selection (especially gut microbiota), production of microbiota metabolites, and the regulation of energy metabolism in adipose tissue, particularly regarding the effects on browning promotion, or on BAT recruitment. In this sense, various types of prebiotics, from complex carbohydrates to phenolic compounds, have been studied regarding their microbiota-modulating role and their effects on crucial tissues for energy metabolism, including adipose tissue. Other studies have analyzed the effects of the main metabolites produced by selected microbiota on the improvement of metabolism, such as short chain fatty acids and secondary bile acids. Here, we focus on state-of-the-art evidence to demonstrate that different prebiotics can have an impact on energy metabolism and the prevention or treatment of obesity (and its associated disorders) by inducing or regulating adaptive thermogenic capacity in WAT and/or BAT, through modulation of microbiota and their derived metabolites.

Gene expression profile of peripheral blood cells (PBC) is able to reflect useful aspects of the whole body metabolic status. Therefore, and favored by the huge development of “omic” technologies, blood cells and, particularly, the peripheral blood mononuclear cell (PBMC) fraction, are emerging as a potent source of transcriptomic biomarkers of health and disease. In this review we describe and discuss the available information concerning the use of the PBC and the PBMC fraction as a crucial tool for nutrigenomic studies. Results of these studies reveal, as these cells are good indicators of metabolic adaptations to diet and, moreover, as they allow us to monitor from early stages on, the metabolic alterations associated with dietary imbalances. In this way, blood cells present the capacity of reflecting higher risks of suffering from diet‐related pathologies, such as obesity and its medical complications. What is more, different studies also show how PBMC are able to evidence the metabolic recovery associated with weight loss or dietary interventions. Besides, recent research points to the utility of ex vivo systems of blood cells to test the efficacy of food bioactives. All in all, PBC constitutes an easily obtainable source of predictive biomarkers of metabolic imbalance and disease related to diet and obesity, and also of metabolic recovery, which appears as highly relevant for developing nutritional preventive strategies in dietetics. Moreover, they could serve to perform relatively simple and economic in vitro tests to assess food bioactive compounds, promoting in this way functional food research and related industry developments.

We aimed to assess the potential effects of hesperidin and capsaicin, independently and in combination, to prevent the development of obesity and its related metabolic alterations in rats fed an obesogenic diet. Three-month-old male Wistar rats were divided into 5 groups: Control (animals fed a standard diet), WD (animals fed a high fat/sucrose (western) diet), HESP (animals fed a western diet + hesperidin (100 mg/kg/day)), CAP (animals fed a western diet + capsaicin (4 mg/kg/day)), and HESP + CAP (animals fed a western diet + hesperidin (100 mg/kg/day) + capsaicin (4 mg/kg/day)). Hesperidin and capsaicin were administered by gavage. Capsaicin decreased body fat gain and prevented insulin resistance, whereas hesperidin showed little effect on body fat gain and no apparent effects on insulin resistance. No additive effects were observed with the combination. Capsaicin and hesperidin, separately, improved blood lipid profile, diminished hepatic lipid accumulation, and prevented non-alcoholic steatohepatitis in western diet-fed rats, but the combination showed lower effects. Hesperidin alone, and to a lesser extent capsaicin or the combination, displayed hypotensive effects in western diet-fed rats. In conclusion, capsaicin and hesperidin, separately, exhibit health beneficial effects on metabolic syndrome-related alterations in western diet-fed rats, but the effects are mitigated with the combination.