High Phenolics Rutgers Scarlet Lettuce Improves Glucose Metabolism in High Fat Diet-Induced Obese Mice

Mol Nutr Food Res. 2016 Nov;60(11):2367-2378. doi: 10.1002/mnfr.201600290. Epub 2016 Aug 16.

Abstract

Scope: The ability of high phenolic Rutgers Scarlet Lettuce (RSL) to attenuate metabolic syndrome and gut dysbiosis was studied in very high fat diet (VHFD)-fed mice. Phenolic absorption was assessed in vivo and in a gastrointestinal tract model.

Methods and results: Mice were fed VHFD, VHFD supplemented with RSL (RSL-VHFD) or store-purchased green lettuce (GL-VHFD), or low-fat diet (LFD) for 13 weeks. Compared to VHFD or GL-VHFD-fed groups, RSL-VHFD group showed significantly improved oral glucose tolerance (p<0.05). Comparison of VHFD, RSL-VHFD, and GL-VHFD groups revealed no significant differences with respect to insulin tolerance, hepatic lipids, body weight gain, fat mass, plasma glucose, triglycerides, free fatty acid, and lipopolysaccharide levels, as well as relative abundances of major bacterial phyla from 16S rDNA amplicon data sequences (from fecal and cecal samples). However, RSL and GL-supplementation increased abundance of several taxa involved in plant polysaccharide degradation/fermentation. RSL phenolics chlorogenic acid, quercetin-3-glucoside, and quercetin-malonyl-glucoside were bioaccessible in the TIM-1 digestion model, but had relatively low recovery.

Conclusions: RSL phenolics contributed to attenuation of post-prandial hyperglycemia. Changes in gut microbiota were likely due to microbiota accessible carbohydrates in RSL and GL rather than RSL phenolics, which may be metabolized, absorbed, or degraded before reaching the colon.

Keywords: Bioaccessibility; Gut microbiota; Lettuce; Metabolic syndrome; Phenolics.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Carbohydrate Metabolism
  • Diet, Fat-Restricted
  • Diet, High-Fat / adverse effects*
  • Dietary Fats / metabolism
  • Gastrointestinal Tract / microbiology
  • Glucose / metabolism
  • Glucose Tolerance Test
  • Hyperglycemia / metabolism
  • Lettuce / chemistry*
  • Liver / metabolism
  • Male
  • Metabolic Syndrome / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Obese
  • Obesity / metabolism
  • Quercetin / analogs & derivatives
  • Triglycerides / metabolism
  • Weight Gain

Substances

  • Dietary Fats
  • Triglycerides
  • isoquercitrin
  • Quercetin
  • Glucose