Age-dependency in the metabolism of flaxseed lignans by healthy adults

Enterolignans: from natural origins to cardiometabolic significance, including chemistry, dietary sources, bioavailability, and activity

The enterolignans, enterolactone and enterodiol, the main metabolites produced from plant lignans by the gut microbiota, have enhanced bioavailability and activity compared to their precursors, with beneficial effects on metabolic and cardiovascular health. Although extensively studied, the biosynthesis, cardiometabolic effects, and other therapeutic implications of mammalian lignans are still incompletely understood. The aim of this review is to provide a comprehensive overview of these phytoestrogen metabolites based on up-to-date information reported in studies from a wide range of disciplines. Established and novel synthetic strategies are described, as are the various lignan precursors, their dietary sources, and a proposed metabolic pathway for their conversion to enterolignans. The methodologies used for enterolignan analysis and the available data on pharmacokinetics and bioavailability are summarized and their cardiometabolic bioactivity is explored in detail. The special focus given to research on the health benefits of microbial-derived lignan metabolites underscores the critical role of lignan-rich diets in promoting cardiovascular health.

Composition, processing, and quality control of whole flaxseed products used to fortify foods

Whole flaxseed (flour) as a good source of omega-3 fatty acid and phytochemicals with excellent nutritional and functional attributes has been used to enrich foods for health promotion and disease prevention. However, several limitations and contemporary challenges still impact the development of whole flaxseed (flour)-enriched products on the global market, such as naturally occurring antinutritional factors and entrapment of nutrients within food matrix. Whole flaxseed (flour) with different existing forms could variably alter the techno-functional performance of food matrix, and ultimately affect the edible qualities of fortified food products. The potential interaction mechanism between the subject and object components in fortified products has not been elucidated yet. Hence, in this paper, the physical structure and component changes of flaxseed (flour) by pretreatments coupled with their potential influences on the edible qualities of multiple fortified food products were summarized and analyzed. In addition, several typical food products, including baked, noodle, and dairy products were preferentially selected to investigate the potential influencing mechanisms of flaxseed (flour) on different substrate components. In particular, the altered balance between water absorption of flaxseed protein/gum polysaccharides and the interruption of gluten network, lipid lubrication, lipid-amylose complexes, syneresis, and so forth, were thoroughly elucidated. The overall impact of incorporating whole flaxseed (flour) on the quality and nutritional attributes of fortified food products, coupled with the possible solutions against negative influences are aimed. This paper could provide useful information for expanding the application of whole flaxseed (flour) based on the optimal edible and nutritional properties of fortified food products.

Strategies to achieve significant physiological concentrations of bioactive phytoestrogens in plasma

The benefits to health attributed to the intake of phytoestrogens (PEs) have been demonstrated in previous studies with significant physiological concentrations of bioactive PEs, such as genistein, equol, enterolignans and urolithins in plasma. However, the achievement of high bioactive PE levels in plasma is restricted to a select population group, mainly due to the low intake of plant PEs and/or the absence, or inhibition, of the microbiota capable of producing these bioactive forms. In this study, the intake of plant PEs, the concentration of bioactive PEs in plasma, the ability of the intestinal microbiota to produce bioactive PEs, as well as the different mechanisms used by GRAS bacteria to increase the level of bioactive PEs were evaluated concluding that the use of GRAS bacteria bioactive PE producers and the development of fermented foods enriched in bioactive PEs in addition to a high intake of plant PEs and taking care of the intestinal microbiota, are some of the different strategies to achieve significant physiological concentrations of bioactive PEs in the intestine and, subsequently, in plasma and targets organs which are essential to improve menopausal symptoms or reduce the risk of some pathologies such as breast and colon cancer, or cardiovascular disease.

Dietary flaxseed: what we know and don't know about its effects on cardiovascular disease

Flaxseed (Linum usitatissimum) is composed of a unique combination of bioactive components that appear to generate, through either an isolated or a synergistic action, a significant beneficial effect on the cardiovascular system. With a significant increase in the generation of data on the dietary impact of flaxseed on the cardiovascular system, a review of where we stand - what we know and what we still need to understand about these effects on the heart and the vasculature - was thought to be of value and the rationale for this paper. For example, although we now know how to deliver the bioactives most efficiently (oil versus ground seed versus whole seed), we do not know how different foods can influence that delivery. Further, we know flaxseed has anti-arrhythmic, anti-atherogenic, anti-hypertensive, and cholesterol-lowering actions in animal studies and some selected human trials but much more needs to be learned, particularly in human trials. These results have justified further commitment of resources to the initiation of human trials. Because of the impact of nutrition on many chronic diseases, this may not only be true for the effects of flaxseed on cardiovascular disease but may be just as relevant for many other disease conditions.

Probiotic Bacteria for Healthier Aging: Immunomodulation and Metabolism of Phytoestrogens

Age-related degeneration gives rise to a number of pathologies, many of them associated with imbalances of the microbiota and the gut-associated immune system. Thus, the intestine is considered a key target organ to improve the quality of life in senescence. Gut microbiota can have a powerful impact in the deterioration linked to aging by its nutritional and immunomodulatory activity. Reduced numbers of beneficial species and low microbial biodiversity in the elderly have been linked with pathogenesis of many diseases. A healthy lifestyle with an elderly customized diet including probiotics can contribute to reducing the chronic proinflammatory status and other age-related pathologies. Beneficial effects of probiotic lactic acid bacteria and bifidobacteria to alleviate some of these disorders based on their immunomodulatory properties as well as their capacity to produce bioactive metabolites from dietary phytoestrogens are summarized. On one hand, the preservation of gut barrier integrity and an increased ability to fight infections are the main reported immune benefits of probiotics. On the other hand, the intake of a diet rich in phytoestrogens along with the presence of selected probiotic bacteria may lead to the production of equol, enterolignans, and urolithins, which are considered protective against chronic diseases related to aging.

Phytoestrogen Metabolism by Adult Human Gut Microbiota

Phytoestrogens are plant-derived polyphenols with a structure similar to human estrogens. The three main groups of phytoestrogens, isoflavones, ellagitannins, and lignans, are transformed into equol, urolithins, and enterolignans, respectively, by bacteria. These metabolites have more estrogenic/antiestrogenic and antioxidant activities than their precursors, and they are more bioavailable. The aim of this study was to analyze the metabolism of isoflavones, lignans and ellagitannins by gut microbiota, and to study the possible correlation in the metabolism of these three groups of phytoestrogens. In vitro fermentation experiments were performed with feces samples from 14 healthy adult volunteers, and metabolite formation was measured by HPLC-PAD and HPLC-ESI/MS. Only the microbiota of one subject produced equol, while most of them showed production of O-desmethylangolensin (O-DMA). Significant inter-subject differences were observed in the metabolism of dihydrodaidzein and dihydrogenistein, while the glucoside isoflavones and their aglycones showed less variability, except for glycitin. Most subjects produced urolithins M-5 and E. Urolithin D was not detected, while uroltithin B was found in half of the individuals analyzed, and urolithins A and C were detected in two and four subjects, respectively. Enterolactone was found in all subjects, while enterodiol only appeared in five. Isoflavone metabolism could be correlated with the metabolism of lignans and ellagitannins. However, the metabolism of ellagitannins and lignans could not be correlated. This the first study where the metabolism of the three groups together of phytoestrogen, isoflavones, lignans, and ellagitannins by gut microbiota is analyzed.