Mediterranean diets and cardiovascular disease

Natural Products to Counteract the Epidemic of Cardiovascular and Metabolic Disorders

Natural products have always been exploited to promote health and served as a valuable source for the discovery of new drugs. In this review, the great potential of natural compounds and medicinal plants for the treatment or prevention of cardiovascular and metabolic disorders, global health problems with rising prevalence, is addressed. Special emphasis is laid on natural products for which efficacy and safety have already been proven and which are in clinical trials, as well as on plants used in traditional medicine. Potential benefits from certain dietary habits and dietary constituents, as well as common molecular targets of natural products, are also briefly discussed. A glimpse at the history of statins and biguanides, two prominent representatives of natural products (or their derivatives) in the fight against metabolic disease, is also included. The present review aims to serve as an "opening" of this special issue of Molecules, presenting key historical developments, recent advances, and future perspectives outlining the potential of natural products for prevention or therapy of cardiovascular and metabolic disease.

The role of diet in prevention and management of type 2 diabetes: implications for public health

The aim of this review is to examine the current scientific knowledge on the relationship between diet and Type 2 diabetes and consider further implications for public health. The review focuses on the main nutritional elements which have been identified as significant in the prevention and management of Type 2 diabetes. Research findings on the role of carbohydrate, fiber, alcohol, and individual fatty acids are discussed, while the role of specific micro-nutrients and the influence of obesity are comprehensively presented. The association between dietary habits and Type 2 diabetes etiology and management is also reviewed, in order to examine the positive effects of adherence to a healthy dietary pattern, including the plausible role of the Mediterranean diet.

Effects of interleukin-33 on cardiac fibroblast gene expression and activity

Interleukin-33 (IL-33) is a recently described member of the interleukin-1 (IL-1) family. It is produced by diverse cell types in response to a variety of stresses including hemorrhage and increased mechanical load. Though only relatively recently discovered, IL-33 has been shown to participate in several pathological processes including promoting type 2 T helper cell-associated autoimmune diseases. In contrast, IL-33 has been also found to have protective effects in cardiovascular diseases. Recent studies have illustrated that IL-33 attenuates cardiac fibrosis induced by increased cardiovascular load in mice (transaortic constriction). Since cardiac fibrosis is largely dependent on increased production of extracellular matrix by cardiac fibroblasts, we hypothesized that IL-33 directly inhibits pro-fibrotic activities of these cells. Experiments have been carried out with isolated rat cardiac fibroblasts to evaluate the effects of IL-33 on the modulation of cardiac fibroblast gene expression and function to test this hypothesis. The expression of the IL-33 receptor, interleukin-1 receptor-like 1 (ST2), was detected at the mRNA and protein levels in isolated adult rat cardiac fibroblasts. Subsequently, the effects of IL-33 treatment (0-100 ng/ml) on the expression of extracellular matrix proteins and pro-inflammatory cytokines/chemokines were examined as well as the effects on rat cardiac fibroblast activities including proliferation, collagen gel contraction and migration. While IL-33 did not directly inhibit collagen I and collagen III production, it yielded a dose-dependent increase in the expression of interleukin-6 and monocyte chemotactic protein-1. Treatment of rat cardiac fibroblasts with IL-33 also impaired the migratory activity of these cells. Further experiments illustrated that IL-33 rapidly activated multiple signaling pathways including extracellular signal-regulated kinases, p38 mitogen-activated protein kinase, c-Jun N-terminal kinases and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) in a dose-dependent manner. Experiments were carried out with pharmacological inhibitors to determine the role of specific signaling pathways in the response of fibroblasts to IL-33. These experiments illustrated that the activation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinases are critical to the increased production of interleukin-6 and monocyte chemotactic protein-1 in response to IL-33. These studies suggest that IL-33 has an important role in the modulation of fibroblast function and gene expression. Surprisingly, IL-33 had no effect on the expression of genes encoding extracellular matrix components or on proliferation, markers typical of fibrosis. The major effects of IL-33 detected in these studies included inhibition of cell migration and activation of cytokine/chemokine expression. The previously reported inhibition of cardiac fibrosis may include more complicated mechanisms that involve other cardiac cell types. Future studies aimed at determining the effects of IL-33 on other cardiac cell types are warranted.

Effects of a Controlled Diet Supplemented with Chickpeas on Serum Lipids, Glucose Tolerance, Satiety and Bowel Function

OBJECTIVE

To compare the effect of a diet supplemented with chickpeas to a wheat-based diet of similar fibre content on serum lipids, glucose tolerance, satiety and bowel function. A third, lower-fibre wheat diet provided further information on dietary fibre quantity and bowel function and satiety.

METHOD

Twenty-seven free-living adults followed two randomized, crossover dietary interventions each of five weeks duration. The chickpea diet included canned drained chickpeas, bread and shortbread biscuits containing 30% chickpea flour. The wheat diet included high-fibre wheat breakfast cereals and wholemeal bread. The diets were isoenergetic to the participants' usual diet, matched for macronutrient content and controlled for dietary fibre. Following on from the second randomised intervention, a sub-group of 18 participants underwent a third, isoenergetic lower-fibre wheat diet that included low-fibre breakfast cereals and bread.

RESULTS

Repeated measures ANOVA revealed reductions in serum TC of 0.25 mmol/L (p < 0.01) and LDL-C of 0.20 mmol/L (p = 0.02) following the chickpea diet compared to the wheat. An unintended significant increase in PUFA and corresponding decrease in MUFA consumption occurred during the chickpea diet and statistical adjustment for this reduced but did not eliminate the effect on serum lipids. There was no significant difference in glucose tolerance. Perceived general bowel health improved significantly during the chickpea diet although there was considerable individual variation. Some participants reported greater satiety during the chickpea diet.

CONCLUSIONS

The small but significant decrease in serum TC and LDL-C during the chickpea diet compared to the equivalent fibre wheat diet was partly due to unintentional changes in macronutrient intake occurring because of chickpea ingestion. If dietary energy and macronutrients were not controlled, chickpea consumption might result in greater benefits via influence on these factors.

Prevention and treatment of the metabolic syndrome

The prevalence of the metabolic syndrome is increasing owing to lifestyle changes leading to obesity. This syndrome is a complex association of several interrelated abnormalities that increase the risk for cardiovascular disease and progression to diabetes mellitus (DM). Insulin resistance is the key factor for the clustering of risk factors characterizing the metabolic syndrome. The National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III defined the criteria for the diagnosis of the metabolic syndrome and established the basic principles for its management. According to these guidelines, treatment involves the improvement of the underlying insulin resistance through lifestyle modification (eg, weight reduction and increased physical activity) and possibly by drugs. The coexistent risk factors (mainly dyslipidemia and hypertension) should also be addressed. Since the main goal of lipid-lowering treatment is to achieve the NCEP low-density lipoprotein cholesterol (LDL-C) target, statins are a good option. However, fibrates (as monotherapy or in combination with statins) are useful for the treatment of the metabolic syndrome that is commonly associated with hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) levels. The blood pressure target is < 140/90 mm Hg. The effect on carbohydrate homeostasis should possibly be taken into account in selecting an antihypertensive drug. Patients with the metabolic syndrome commonly have other less well-defined metabolic abnormalities (eg, hyperuricemia and raised C-reactive protein levels) that may also be associated with an increased cardiovascular risk. It seems appropriate to manage these abnormalities. Drugs that beneficially affect carbohydrate metabolism and delay or even prevent the onset of DM (eg, thiazolidinediones or acarbose) could be useful in patients with the metabolic syndrome. Furthermore, among the more speculative benefits of treatment are improved liver function in nonalcoholic fatty liver disease and a reduction in the risk of acute gout.