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1. The nexus of gut microbiota, diet, and health

   https://doi.org/10.31989/ffs.v2i2.885  

   Bhattarai, Sajal; Janaswamy, Srinivas (February 2022, Functional Food Science)

   The gut microbiome incorporates the ecological niche specific to the totality of the microorganisms in the human gut. Unique to every individual, the blueprint of the microbiome sets up at birth and functions as a human organ and plays a significant role in digestion, detoxification, fighting pathogens, modulating the immune system, and improving health. The gut microbiota and associated health implications are influenced by factors such as birth and age, diseases, use of antibiotics and food components (e.g., complex carbohydrates and dietary fibers, plant proteins, unsaturated fatty acids, and functional compounds of natural origin such as flavones, flavonoids, polyphenols, and antioxidants). Toward this end, diet and the gut microbiome interact and govern each other’s fate. Herein, gut dysbiosis, the alteration of natural state and composition of the gut microbiome, and the gut microflora diversity modulated by food constituents and associated health effects have been discussed. The gut microbiota composition and related metabolites are influenced by the diet which in turn modulates human health. The outcome is deemed to aid in developing personalized diet recommendations (based on the unique gut microbiome) toward improving human health. Keywords: gut microbiome, gut microbiota, gut dysbiosis, short-chain fatty acids, metabolites, health modulation 

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2. Structure-activity assessment of flavonoids as modulators of copper transport

   https://doi.org/10.3389/fchem.2022.972198  

   Lee, Vanessa J.; Heffern, Marie C. (August 2022, Frontiers in Chemistry)

   Flavonoids are polyphenolic small molecules that are abundant in plant products and are largely recognized for their beneficial health effects. Possessing both antioxidant and prooxidant properties, flavonoids have complex behavior in biological systems. The presented work investigates the intersection between the biological activity of flavonoids and their interactions with copper ions. Copper is required for the proper functioning of biological systems. As such, dysregulation of copper is associated with metabolic disease states such as diabetes and Wilson’s disease. There is evidence that flavonoids bind copper ions, but the biological implications of their interactions remain unclear. Better understanding these interactions will provide insight into the mechanisms of flavonoids’ biological behavior and can inform potential therapeutic targets. We employed a variety of spectroscopic techniques to study flavonoid-Cu(II) binding and radical scavenging activities. We identified structural moieties important in flavonoid-copper interactions which relate to ring substitution but not the traditional structural subclassifications. The biological effects of the investigated flavonoids specifically on copper trafficking were assessed in knockout yeast models as well as in human hepatocytes. The copper modulating abilities of strong copper-binding flavonoids were largely influenced by the relative hydrophobicities. Combined, these spectroscopic and biological data help elucidate the intricate nature of flavonoids in affecting copper transport and open avenues to inform dietary recommendations and therapeutic development. 

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3. Effect of dietary macronutrients and immune challenge on gut microbiota, physiology and feeding behaviour in zebra finches

   https://doi.org/10.1111/mec.17428  

   Love, Ashley C; Tabb, Victoria; Youssef, Noha H; Wilder, Shawn M; DuRant, Sarah E (July 2024, Molecular Ecology)

   Bonneaud, Camille (Ed.)

   Abstract Macronutrients play a vital role in host immunity and can influence host–pathogen dynamics, potentially through dietary effects on gut microbiota. To increase our understanding of how dietary macronutrients affect physiology and gut microbiota and investigate whether feeding behaviour is influenced by an immune threat, we conducted two experiments. First, we determined whether zebra finches (Taeniopygia guttata) exhibit shifts in physiology and gut microbiota when fed diets differing in macronutrient ratios. We found the type and amount of diet consumed affected gut microbiota alpha diversity, where microbial richness and Shannon diversity increased with caloric intake in birds fed a high‐fat diet and decreased with caloric intake in birds fed a high protein diet. Diet macronutrient content did not affect physiological metrics, but lower caloric intake was associated with higher complement activity. In our second experiment, we simulated an infection in birds using the bacterial endotoxin lipopolysaccharide (LPS) and quantified feeding behaviour in immune challenged and control individuals, as well as birds housed near either a control pair (no immune threat), or birds housed near a pair given an immune challenge with LPS (social cue of heightened infection risk). We also examined whether social cues of infection alter physiological responses relevant to responding to an immune threat, an effect that could be mediated through shifts in feeding behaviour. LPS induced a reduction in caloric intake driven by a decrease in protein, but not fat consumption. No evidence was found for socially induced shifts in feeding behaviour, physiology or gut microbiota. Our findings carry implications for host health, as sickness‐induced anorexia and diet‐induced shifts in the microbiome could shape host–pathogen interactions. 

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4. Dietary preservatives alter the gut microbiota in vitro and in vivo with sex-specific consequences for host metabolic development

   https://doi.org/10.1101/2024.05.14.593600  

   Schell, Laura D; Chadaideh, Katia S; Allen-Blevins, Cary R; Venable, Emily M; Carmody, Rachel N (May 2024, bioRxiv)

   ABSTRACT: Antibiotics in early life can promote adiposity via interactions with the gut microbiota. However, antibiotics represent only one possible route of antimicrobial exposure. Dietary preservatives exhibit antimicrobial activity, contain chemical structures accessible to microbial enzymes, and alter environmental conditions favoring specific microbial taxa. Therefore, preservatives that retain bioactivity in the gut might likewise alter the gut microbiota and host metabolism. Here we conduct in vitro, ex vivo, and in vivo experiments in mice to test the effects of preservatives on the gut microbiota and host physiology. We screened common dietary preservatives against a panel of human gut isolates and whole fecal communities, finding that preservatives strongly altered microbial growth and community structure. We exposed mice to diet-relevant doses of 4 preservatives [acetic acid, BHA (butylated hydroxyanisole), EDTA (ethylenediaminetetraacetic acid) and sodium sulfite], which each induced compound-specific changes in gut microbiota composition. Finally, we compared the long-term effects of early-life EDTA and low-dose antibiotic (ampicillin) exposure. EDTA exposure modestly reduced nutrient absorption and cecal acetate in both sexes, resulting in lower adiposity in females despite greater food intake. Females exposed to ampicillin also exhibited lower adiposity, along with larger brains and smaller livers. By contrast, in males, ampicillin exposure generally increased energy harvest and decreased energy expenditure, resulting in higher adiposity. Our results highlight the potential for everyday doses of common dietary preservatives to affect the gut microbiota and impact metabolism differently in males and females. Thus, despite their generally-regarded-as-safe designation, preservatives could have unintended consequences for consumer health. 

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5. Gut Microbiome: Profound Implications for Diet and Disease

   https://doi.org/10.3390/nu11071613  

   Hills, Ronald D.; Pontefract, Benjamin A.; Mishcon, Hillary R.; Black, Cody A.; Sutton, Steven C.; Theberge, Cory R. (July 2019, Nutrients)

   The gut microbiome plays an important role in human health and influences the development of chronic diseases ranging from metabolic disease to gastrointestinal disorders and colorectal cancer. Of increasing prevalence in Western societies, these conditions carry a high burden of care. Dietary patterns and environmental factors have a profound effect on shaping gut microbiota in real time. Diverse populations of intestinal bacteria mediate their beneficial effects through the fermentation of dietary fiber to produce short-chain fatty acids, endogenous signals with important roles in lipid homeostasis and reducing inflammation. Recent progress shows that an individual’s starting microbial profile is a key determinant in predicting their response to intervention with live probiotics. The gut microbiota is complex and challenging to characterize. Enterotypes have been proposed using metrics such as alpha species diversity, the ratio of Firmicutes to Bacteroidetes phyla, and the relative abundance of beneficial genera (e.g., Bifidobacterium, Akkermansia) versus facultative anaerobes (E. coli), pro-inflammatory Ruminococcus, or nonbacterial microbes. Microbiota composition and relative populations of bacterial species are linked to physiologic health along different axes. We review the role of diet quality, carbohydrate intake, fermentable FODMAPs, and prebiotic fiber in maintaining healthy gut flora. The implications are discussed for various conditions including obesity, diabetes, irritable bowel syndrome, inflammatory bowel disease, depression, and cardiovascular disease. 

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