A weight loss plan containing vegatables and fruits comprises pectins (plant polysaccharides). Pectin can’t be metabolized by mammalian cells within the gastrointestinal tract but is fermented by the gut microbiota within the colon, where short-chain fatty acids (SCFAs) are released. Previous studies have examined pectin’s prebiotic properties. Nevertheless, the outcomes have been inconsistent, most definitely due to differences in its chemical structure, which varies with its molecular weight and degree of esterification.
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Composition of Pectin
The plant cell wall comprises pectin (heteropolysaccharide), a posh structure comprising O-1 and O-4 linked galacturonic acids (GalA). It also comprises three major units, namely, rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II), and homogalacturonan (HG). Typically, the structure of pectin is very variable, differing between plants and across different developmental phases (e.g., fruit ripening).
Pectin molecules have been categorized based on two parameters, i.e., degree of esterification (DE) and molecular weight (MW). DE can be known as the degree of methoxylation (DM), i.e., the percent composition of methyl-esterified GalA in comparison with GalA. A low degree of esterification pectin (LDE) is observed in a pectin molecule that comprises lower than 50% DE, while those with DE above 50% represent a high degree of esterification pectin (HDE).
The Role of Gut Microbiome in Pectin Fermentation
The gut microbiome comprises a posh bacterial population that plays a significant role in human health. The gut microbiome protects hosts from pathogenic colonization through physical and nutrient competition. Moreover, they synthesize vitamins and produce a big selection of metabolites, resembling short-chain fatty acids (SCFA), which might alter the immune system.
Gut microbiota can ferment pectin due to the presence of bacterial species that carry polysaccharide utilization loci (PULs) and produce carbohydrate-active enzymes. These enzymes can break down pectin molecules and permit pectin for use as a carbon source that subsequently ends within the production of SCFAs.
The important thing pectin-degrading bacteria has been identified to be Bacteroides species (e.g., Bacteroides thetaiotamicron). Moreover, species belonging to Lachnospiraceae family also contain pectin-degrading enzymes, resembling hydrolases, lyases, and esterases. Another microbes which are related to pectin fermentation are Faecalbacterium prausnitzii and Eubacterium eligens.
Pectin fermentation by gut microbiota is dependent upon the chemical properties of the pectin, particularly DE and MW. Pectin with lower MW has the next fermentation rate and elevated SCFA yield. Previous in vitro studies based on citrus pectin and sugar beet pectin indicated DE to be probably the most crucial parameter for pectin modification of the gut microbiota. These studies have indicated that MW and DE of pectin influence its fermentability by the gut microbiota and affect its prebiotic potential. Hence, it’s imperative to elucidate how these structural components of pectin affect gut microbiota composition.
How do MW and DE Affect the Prebiotic Function of Lemon Pectin on the Gut Microbiota?
A recent Foods journal study has evaluated how MW and DE affect the prebiotic function of lemon pectin on the gut microbiota. An in vitro experimental design was used to know the interactions between pectin and gut microbes. This experimental design successfully eliminated the multifarious interactions that occur between mammalian cells and gut microbiota in in vivo animal models. 16S rRNA gene sequencing and SCFA evaluation were used to find out the alterations in gut microbiota community structure and performance.
For the in vitro study, two lemon pectins of various MW and DE were tested against the gut microbiota of two donors. The authors found that each high DE lemon pectin (LMW-HDE) and low DE lemon pectin (HMW-LDE) could alter the gut microbiota community structure.
It was observed that each lemon pectins enhanced total levels of SCFAS through the elevation of several types of SCFAs. LMW-HDE lemon pectin enhanced the degrees of acetic and butanoic acids, while HMW-LDE lemon pectin only increased acetic acid.
Interestingly, it was observed that HMW-LDE elevated taxa inside Lachnospiraceae in each donors. The finding of this study is consistent with previous studies that reported elevated Lachnospiraceae following pectin treatment. For LMW-HDE lemon pectin, changes in the degrees of Paraprevotella, Acidaminococcus, Psuedoramibacter, Alistipes, and Fusobacterium were found.
Weighted and unweighted UniFrac analyses revealed that probably the most significant divergence for each LMW-HDE and HMW-LDE lemon pectins was as a consequence of donor composition and never pectin treatment. Nevertheless, no significant change within the microbial community was observed throughout the donor.
