Lignans and Gut Microbiota: An Interplay Revealing Potential Health Implications

Abstract

Plant polyphenols are a broad group of bioactive compounds characterized by different chemical and structural properties, low bioavailability, and several in vitro biological activities. Among these compounds, lignans (a non-flavonoid polyphenolic class found in plant foods for human nutrition) have been recently studied as potential modulators of the gut–brain axis. In particular, gut bacterial metabolism is able to convert dietary lignans into therapeutically relevant polyphenols (i.e., enterolignans), such as enterolactone and enterodiol. Enterolignans are characterized by various biologic activities, including tissue-specific estrogen receptor activation, together with anti-inflammatory and apoptotic effects. However, variation in enterolignans production by the gut microbiota is strictly related to both bioaccessibility and bioavailability of lignans through the entire gastrointestinal tract. Therefore, in this review, we summarized the most important dietary source of lignans, exploring the interesting interplay between gut metabolites, gut microbiota, and the so-called gut–brain axis.

Polyphenols of the Mediterranean Diet and Their Metabolites in the Prevention of Colorectal Cancer

“…The same transformation process applies to certain isoflavones, prenylfavonoids, lignans, and stilbenes such as reveratrol [55]. The metabolism of intestinal bacteria can also convert food lignans (a non-flavonoid polypheno-lic class found in plant foods) into therapeutically relevant polyphenols (i.e., enterolignans) such as enterolactone and enterodiol [56]. Ellagic tannins (substances from the polyphenol family) from the pomegranate are transformed into urolithin A, a mitophagy-activating polyphenol, which increases the lifespan of the worm Caenorhabditis elegans, running endurance in rodents (rats, mice), and transcription of mitochondrial genes in human muscle tissue [57].…”

Untargeted Phytochemical Profile, Antioxidant Capacity and Enzyme Inhibitory Activity of Cultivated and Wild Lupin Seeds from Tunisia

“…In this regard, gut bacterial metabolism is able to convert dietary lignans into therapeutically relevant enterolignans, such as enterolactone and enterodiol. Enterolignans are characterized by various biologic activities, including antioxidant, anti-inflammatory and apoptotic effects [41]. Interestingly, the potential of lignans to inhibit carbonic anhydrase, AChE and BChE, may represent a valid strategy towards neuroprotection, in order to prevent memory loss events (typical of Alzheimer's-affected patients) [42,43].…”

Do Bioactive Food Compound with Avena sativa L., Linum usitatissimum L. and Glycine max L. Supplementation with Moringa oleifera Lam. Have a Role against Nutritional Disorders? An Overview of the In Vitro and In Vivo Evidence

“…The modulation of the intestinal microbiota can also occur by using flaxseed, which is rich in multiple bioactive compounds, especially lignans [ 181 , 182 ], PUFAs and secoisolariciresinol diglucoside (SDG), with anti-inflammatory properties [ 183 ]. Lignans, which are non-steroidal phytoestrogens, are metabolized by intestinal bacteria to access the systemic circulation in humans [ 184 ].…”

“…SDG liberates secoisolariciresinol (SECO), which produces dihydroxyalododiol by demethylation by the microbiota and, by dihydroxylation, results in enterodiol and dehydrogenation produces enterolactone [ 182 , 185 , 186 ]. All these metabolic processes occur by the bio transforming action of intestinal bacteria, such as Ruminococcus bromii and R. lactaris [ 187 , 188 ], Lactobacillus casei and L. acidophilus , acting for the digestion of the whole flaxseed, to increase the bioaccessibility of the enterodiol [ 189 ].…”