Whole Rye Consumption Improves Blood and Liver n-3 Fatty Acid Profile and Gut Microbiota Composition in Rats

PLoS One. 2016 Feb 10;11(2):e0148118. doi: 10.1371/journal.pone.0148118. eCollection 2016.

Abstract

Background: Whole rye (WR) consumption seems to be associated with beneficial health effects. Although rye fiber and polyphenols are thought to be bioactive, the mechanisms behind the health effects of WR have yet to be fully identified. This study in rats was designed to investigate whether WR can influence the metabolism of n-3 and n-6 long-chain fatty acids (LCFA) and gut microbiota composition.

Methods: For 12 weeks, rats were fed a diet containing either 50% WR or 50% refined rye (RR). The WR diet provided more fiber (+21%) and polyphenols (+29%) than the RR diet. Fat intake was the same in both diets and particularly involved similar amounts of essential (18-carbon) n-3 and n-6 LCFAs.

Results: The WR diet significantly increased the 24-hour urinary excretion of polyphenol metabolites-including enterolactone-compared with the RR diet. The WR rats had significantly more n-3 LCFA-in particular, eicosapentanoic (EPA) and docosahexanoic (DHA) acids-in their plasma and liver. Compared with the RR diet, the WR diet brought significant changes in gut microbiota composition, with increased diversity in the feces (Shannon and Simpson indices), decreased Firmicutes/Bacteroidetes ratio and decreased proportions of uncultured Clostridiales cluster IA and Clostridium cluster IV in the feces. In contrast, no difference was found between groups with regards to cecum microbiota. The WR rats had lower concentrations of total short-chain fatty acids (SCFA) in cecum and feces (p<0.05). Finally, acetate was lower (p<0.001) in the cecum of WR rats while butyrate was lower (p<0.05) in the feces of WR rats.

Interpretation: This study shows for the first time that WR consumption results in major biological modifications-increased plasma and liver n-3 EPA and DHA levels and improved gut microbiota profile, notably with increased diversity-known to provide health benefits. Unexpectedly, WR decreased SCFA levels in both cecum and feces. More studies are needed to understand the interactions between whole rye (fiber and polyphenols) and gut microbiota and also the mechanisms of action responsible for stimulating n-3 fatty acid metabolism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Weight
  • Cecum / metabolism
  • Diet*
  • Docosahexaenoic Acids / blood
  • Docosahexaenoic Acids / metabolism
  • Eicosapentaenoic Acid / blood
  • Eicosapentaenoic Acid / metabolism
  • Fatty Acids, Omega-3 / metabolism*
  • Fatty Acids, Omega-6 / metabolism*
  • Feces
  • Feeding Behavior
  • Gastrointestinal Microbiome*
  • Intestines / microbiology*
  • Liver / metabolism*
  • Male
  • Mass Spectrometry
  • Oligonucleotide Array Sequence Analysis
  • Polyphenols / chemistry
  • Rats
  • Rats, Wistar
  • Secale*

Substances

  • Fatty Acids, Omega-3
  • Fatty Acids, Omega-6
  • Polyphenols
  • Docosahexaenoic Acids
  • Eicosapentaenoic Acid

Grants and funding

This project has been funded by Barilla G. R. Fratelli Spa and supported in part by the 7th Framework Program ATHENA [Grant agreement no.: 245121] from the European Community. The funding is managed by the Grenoble University (School of Medicine) without involvement of the funders. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.