The Effects of Vegetarian and Vegan Diets on Gut Microbiota

Abstract

The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. Additionally, vegans and vegetarians have significantly higher counts of certain Bacteroidetes -related operational taxonomic units compared to omnivores. Fibers (that is, non-digestible carbohydrates, found exclusively in plants) most consistently increase lactic acid bacteria, such as Ruminococcus, E. rectale , and Roseburia , and reduce Clostridium and Enterococcus species. Polyphenols, also abundant in plant foods, increase Bifidobacterium and Lactobacillus , which provide anti-pathogenic and anti-inflammatory effects and cardiovascular protection. High fiber intake also encourages the growth of species that ferment fiber into metabolites as short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. The positive health effects of SCFAs are myriad, including improved immunity against pathogens, blood–brain barrier integrity, provision of energy substrates, and regulation of critical functions of the intestine. In conclusion, the available literature suggests that a vegetarian/vegan diet is effective in promoting a diverse ecosystem of beneficial bacteria to support both human gut microbiome and overall health. This review will focus on effects of different diets and nutrient contents, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health.

Calcium Oxalate Nephrolithiasis and Gut Microbiota: Not just a Gut-Kidney Axis. A Nutritional Perspective

“…These compounds can in fact be metabolized by several microbial species and represent the main substrate for the synthesis of SCFA (acetate, butyrate, propionate) by the microbiota. Several studies indicate that high fiber intake is also able to modulate the gut microbiota composition towards an increase of representation of SCFA-producing species, lactic acid bacteria, and species with purported health-promoting actions, including Faecalibacterium, Bifidobacterium, and Lactobacillus, at the expense of a reduction of pathobionts [134][135][136]. These differences also emerged when comparing subjects who follow a Mediterranean-style diet with subjects who follow a Western-style diet [93,94].…”

Antibiotics impair immune checkpoint inhibitor effectiveness in Hispanic patients with non‐small cell lung cancer (AB‐CLICaP)

“…24 Hence, therapeutic modulation of the human microbiome has been proposed for the treatment of different disease entities. Diverse strategies such as dietary modifications, 25 antibiotic treatment (ATB) 26 and even fecal transplants have been tested in a variety of settings. [27][28][29][30][31] A high biodiversity and proper balance between microbiota species is essential for a commensal and symbiotic relationship, whereas the disruption of these factors could lead to a nonwarranted immune response.…”

You Are What You Eat—The Relationship between Diet, Microbiota, and Metabolic Disorders—A Review

“…A majority of previous studies have concluded that protein consumption positively correlates with overall microbial diversity, but there are significant differences in bacterial enterotypes between individuals preferring animal-derived proteins versus plant-derived proteins. Consumption of animal-based protein is associated with an increase in counts of bile-tolerant anaerobes, such as Bacteroides, Alistipes, and Bilophila [59,60]. This relationship has also been described by Filippo et al [61] in a study comparing GM of Italian children with that of children from Burkina Faso.…”

“…The GM composition (especially in the proportion of Bacteroidetes, Prevotella, and Ruminococcus) differs between individuals on vegan or vegetarian diets and omnivores, which has been well documented in previous studies [59]. Among the reasons for these changes are differences in bacteria directly consumed together with food, variations in pH, GI tract transit time, and differences in the number of substrates supplied for bacterial fermentation from the diet [59].…”

“…Ruminococcus is responsible for the degradation of complex CHO (cellulose, RS) and plays a role in the conversion of animal-derived choline to trimethylamine (TMA). Previous studies have reported that an abundance of Ruminococcus is positively correlated with butyrate production, lower endotoxemia, lower arterial stiffness, and lower BMI [59].…”