Modulation of the Gut Microbiota Structure and Function by Two Structurally Different Lemon Pectins

Authors: Firrman, Jenni; Mahalak, Karley; BOBOKALONOV, JAMSHED - Oak Ridge Institute For Science And Education (ORISE); Liu, Linshu; LEE, JUNG-JIN - The Children'S Hospital Of Philadelphia; BITTINGER, KYLE - The Children'S Hospital Of Philadelphia; MATTEI, LISA - The Children'S Hospital Of Philadelphia; Gadaingan, Rizalina; Narrowe, Adrienne; Scarino Lemons, Johanna

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2022
Publication Date: 12/1/2022
Citation: Firrman, J., Mahalak, K.K., Bobokalonov, J., Liu, L.S., Lee, J., Bittinger, K., Mattei, L., Gadaingan, R.T., Narrowe, A.B., Scarino Lemons, J.M. 2022. Modulation of the Gut Microbiota Structure and Function by Two Structurally Different Lemon Pectins. Foods. https://doi.org/10.3390/foods11233877.
DOI: https://doi.org/10.3390/foods11233877

Interpretive Summary: Pectins are plant polysaccharides consumed as part of a diet containing fruits and vegetables and are considered beneficial to human health. After ingestion, the human cells in the digestive tract are unable to digest pectin, but the gut microbiota, a large community of microbes in the colon, produce enzymes that can break down the pectin and convert it into healthy byproducts. The healthy byproducts are then able to exert the health benefits associated with pectin. However, pectin can vary in size and complexity, and this makes a difference in the ability for the gut microbiota to break it down and determines which types of healthy byproducts are released. Here, we studied how pectins of different sizes and complexity would affect the gut microbiota and if this would play a role in which healthy byproducts were produced. We found that a smaller, more complex pectin did not affect the gut microbiota in a distinguishable way, but that a larger, less complex pectin was able to increase levels of some beneficial gut microbes. We also found that the smaller, more complex pectin and the large, less complex pectin both produced healthy byproducts, but of different types. In conclusion, this study shows how pectin size and complexity influences the way the gut microbiota breaks it down and determines the types of healthy byproducts released.

Technical Abstract: Pectins are plant polysaccharides consumed as part of a diet containing fruits and vegetables. Inside the gastrointestinal tract, pectin cannot be metabolized by the mammalian cells but is fermented by the gut microbiota in the colon with the subsequent release of the end products short chain fatty acids (SCFA). A number of studies have evaluated the prebiotic effect of pectin on the gut microbiota, but the results have been inconsistent, most likely due to differences in the chemical structures of the pectins used. Pectins show ranges in molecular weight (MW) and are characterized based on the percentage of esterified galacturonic acid, or degree of esterification (DE). Both structural parameters have been found to alter utilization of pectin by the gut microbiota. Here, the effects of two different MW lemon pectins with varying DEs, on the gut microbiota of two donors, were evaluated in vitro. The results found that low MW, high DE lemon pectin (LMW-HDE) altered community structure in a donor-dependent manner, whereas high MW, low DE lemon pectin (HMW-LDE) increased levels of Lachnospiraceae in both donors tested. Both LMW-HDE and HMW-LDE lemon pectins increased total short chain fatty acid levels (SCFAs) for both donors; however, an increase in butanoic and pentanoic acids was observed for LMW-HDE while an increase in acetic and propanoic acids was observed for HMW-LDE. Together, this data provides valuable information linking the chemical structure of pectin to its effect on the gut microbiota, which is important to understanding its function as a prebiotic.