Dietary fibre as a unifying remedy for the whole spectrum of obesity-associated cardiovascular risk

Obesity is a pandemic carrying the heavy burden of multiple and serious co-morbidities including metabolic syndrome, type 2 diabetes and cardiovascular diseases. The pathophysiological processes leading to the accumulation of body fat slowly evolve to fat accumulation in other body compartments than subcutaneous tissue. This abnormal fat deposition determines insulin resistance which in turn causes blood glucose and lipid metabolism derangement, non-alcoholic fatty liver disease, hypertension, and metabolic syndrome. All these conditions contribute to increase the cardiovascular risk of obese people. Several randomized clinical trials demonstrated that moderate weight loss (5–10%) in obese patients improves obesity-related metabolic risk factors and coexisting disorders. Therefore, nutritional strategies able to facilitate weight management, and in the meantime positively influence obesity-associated cardiovascular risk factors, should be implemented. To this aim, a suitable option could be dietary fibres that may also act independently of weight loss. The present narrative review summarizes the current evidence about the effects of dietary fibres on weight management in obese people. Moreover, all of the different cardiovascular risk factors are individually considered and evidence on cardiovascular outcomes is summarized. We also describe the plausible mechanisms by which different dietary fibres could modulate cardio-metabolic risk factors. Overall, despite both epidemiological and intervention studies on weight loss that show statistically significant but negligible clinical effects, dietary fibres seem to have a beneficial impact on main pathophysiological pathways involved in cardiovascular risk (i.e., insulin resistance, renin-angiotensin, and sympathetic nervous systems). Although the evidence is not conclusive, this suggests that fibre would be a suitable option to counteract obesity-related cardio-metabolic diseases also independently of weight loss. However, evidence is not consistent for the different risk factors, with clear beneficial effects shown on blood glucose metabolism and Low Density Lipoprotein (LDL) cholesterol while there is fewer, and less consistent data shown on plasma triglyceride and blood pressure. Ascribing the beneficial effect of some foods (i.e., fruits and vegetables) solely to their fibre content requires more investigation on the pathophysiological role of other dietary components, such as polyphenols

Nutritional factors influencing plasma adiponectin levels: results from a randomised controlled study with whole-grain cereals

Data from intervention studies about the effects of a high intake of whole-grain cereals on adiponectin expression are still inconclusive. We evaluated the effects of whole-grain or refined cereals on fasting and postprandial serum adiponectin in people at high cardiovascular risk. According to a randomised controlled parallel group design, participants with metabolic syndrome were assigned to an isoenergetic diet based on either whole-grain cereal (WGC) or refined cereal (RC) products for 12-weeks. Anthropometric and biochemical measures were taken. Compared to baseline, fasting and postprandial serum adiponectin levels increased after both RC and WGC. In the WGC and RC groups combined, adiponectin concentrations significantly increased after 12-week intervention, and are directly associated with plasma SCFAs and acetate. Only increasing whole-grain cereals may not influence adiponectin levels, which could be modified by a fibre rich, low-fat, low-glycemic index diet, possibly through changes in gut microbiota, as suggested by the relation with SCFAs. Clinical Trials number: NCT00945854

Reduction in liver fat by dietary MUFA in type 2 diabetes is helped by enhanced hepatic fat oxidation

The aim of this work was to investigate hepatic lipid metabolic processes possibly involved in the reduction of liver fat content (LF) observed in patients with type 2 diabetes after an isoenergetic diet enriched in monounsaturated fatty acids (MUFAs)

Polyphenol-rich diets improve glucose metabolism in people at high cardiometabolic risk: a controlled randomised intervention trial

Dietary polyphenols and long chain n-3 polyunsaturated fatty acids (LCn3) are associated with lower cardiovascular risk. This may relate to their influence on glucose metabolism and diabetes risk. We evaluated the effects of diets naturally rich in polyphenols and/or LCn3 of marine origin on glucose metabolism in people at high cardiometabolic risk

Urine 8-isoprostane in relation to adiposity and insulin resistance in individuals at high cardiometabolic risk

Oxidative stress has been implicated in the pathogenesis of many conditions, including insulin resistance and obesity. However, in vivo data concerning these relationships are scarce and conflicting. Therefore, the aim of this study was to investigate the association of oxidative stress with abdominal adiposity and insulin resistance in individuals at high cardiometabolic risk