A group studied the effects of apples in a mouse model to determine if there was a positive consequence in the changes related to bacterial communities and inflammation markers.[1]
Apples are rich in polyphenols, which provide antioxidant properties, mediation of cellular processes such as inflammation, and modulation of gut microbiota. In this study we compared genetically engineered apples with increased flavonoids [myeloblastis transcription factor 10 (MYB10)] with nontransformed apples from the same genotype, “Royal Gala” (RG), and a control diet with no apple.
Compared with the RG diet, the MYB10 diet contained elevated concentrations of the flavonoid subclasses anthocyanins, flavanol monomers (epicatechin) and oligomers (procyanidin B2), and flavonols (quercetin glycosides), but other plant secondary metabolites were largely unaltered. We used these apples to investigate the effects of dietary flavonoids on inflammation and gut microbiota in 2 mouse feeding trials.
In trial 1: male mice were fed a control diet or diets supplemented with 20% MYB10 apple flesh and peel (MYB-FP) or RG apple flesh and peel (RG-FP) for 7 d.
In trial 2: male mice were fed MYB-FP or RG-FP diets or diets supplemented with 20% MYB10 apple flesh or RG apple flesh for 7 or 21 d.
In trial 1, the transcription levels of inflammation-linked genes in mice showed decreases of >2-fold for interleukin-2 receptor (Il2rb), chemokine receptor 2 (Ccr2), chemokine ligand 10 (Cxcl10), and chemokine receptor 10 (Ccr10) at 7 d for the MYB-FP diet compared with the RG-FP diet (P < 0.05).
In trial 2, the inflammation marker prostaglandin E(2) (PGE(2)) in the plasma of mice fed the MYB-FP diet at 21 d was reduced by 10-fold (P < 0.01) compared with the RG-FP diet. In colonic microbiota, the number of total bacteria for mice fed the MYB-FP diet was 6% higher than for mice fed the control diet at 21 d (P = 0.01).
In summary, high-flavonoid apple was associated with decreases in some inflammation markers and changes in gut microbiota when fed to healthy mice.
Commentary
The role of apples selected for their flavonoid concentrations (preferably organic and non GMO!) have notifiable effects on gut bacteria composition and reduce inflammation markers, suggesting once again that this fruit may be utilised as part of a therapeutic food approach to inflammation originating in the gastrointestinal tract, where the mechanisms involve dysbiosis and inflammatory responses. In part this is a paper that adds ongoing value to the old adage that an apple (read 2) a day confers benefits to health.[2],[3]
References
[1] Espley RV, Butts CA, Laing WA, Martell S, Smith H, McGhie TK, Zhang J, Paturi G, Hedderley D, Bovy A, Schouten HJ, Putterill J, Allan AC, Hellens RP. Dietary flavonoids from modified apple reduce inflammation markers and modulate gut microbiota in mice. J Nutr. 2014 Feb;144(2):146-54. View Full Paper
[2] Jung M, Triebel S, Anke T, Richling E, Erkel G. Influence of apple polyphenols on inflammatory gene expression. Mol Nutr Food Res. 2009 Oct;53(10):1263-80 View Abstract
[3] Skyberg JA, Robison A, Golden S, Rollins MF, Callis G, Huarte E, Kochetkova I, Jutila MA, Pascual DW. Apple polyphenols require T cells to ameliorate dextran sulfate sodium-induced colitis and dampen proinflammatory cytokine expression. J Leukoc Biol. 2011 Dec;90(6):1043-54 View Full Paper
