Data from a study with mice indicated that adding extracts from genetically engineered apples with increased flavonoids led to 10-fold decrease in levels of pro-inflammatory prostaglandins than extracts from non-transformed apples.
In addition, the total number of bacteria in the colons of animals fed a diet containing the transformed apple extracts was 6% higher than for mice fed the control diet, said the researchers in the Journal of Nutrition.
“This targeted approach to engineering fruit provides opportunities to test the relation between different classes of phytochemicals and the gut microbiota to understand the mechanisms behind the proposed health benefits,” wrote the researchers, led by Richard Espley.
“The findings here further demonstrate that apple consumption affects aspects of inflammatory pathways and the gut microbiota.
“Future studies might include human or human gut model confirmation of changes in inflammation marker concentrations and a more detailed analysis of modulation of particular groups of gut microbial populations.”
Polyphenols and gut health
Hippocrates once said, ‘All disease starts in the gut’, and the potential for polyphenols to influence the gut microbiota and positively impact human health is only beginning to be understood.
Dr Jess Reed from the University of Wisconsin told attendees at the Berry Health Symposium in Charlotte last year that, while some polyphenols from sources such as berries undergo extensive metabolism in the gut, compounds such as proanthocyanidins are not metabolized and the bioavailability of these compounds is low.
According to the new paper, apples are a rich source of polyphenols, and the engineered apples used in their study have elevated levels of compounds such as anthocyanins, epicatechin, procyanidin B2, and quercetin glycosides.
In collaboration with scientists from Plant Research International (The Netherlands), and the University of Auckland, Espley and his co-workers investigated the effects of the polyphenols to influence inflammation and gut microbiota.
Two feeding trials were performed with mice. For the first, male mice were fed a standard diet with or without flesh and peel of transformed or non-transformed apples for one week. In the second trial, mice were fed apple-flesh only diets for a further two weeks.
Results showed that levels of inflammation-linked genes were decreased in the transformed apple groups, compared to the non-transformed apple.
The second trial showed that prostaglandin E2 levels were reduced by 10-fold in the transformed apple groups, compared to the non-transformed apple.
“There is much evidence that the composition of the human intestinal microbiota has an influence on health and the incidence of disease and that gut health is largely determined by the complex interaction between host and gastrointestinal microbiota,” wrote the researchers.
“Whereas the diversity and complexity of both microbial flora and its interaction with the host cannot be underestimated, our results further suggest that a diet high in apple polyphenols can alter microbial populations and thus affect inflammation and general gastrointestinal health.”
Source: Journal of Nutrition
2014, Volume 144, Pages 146-154
“Dietary Flavonoids from Modified Apple Reduce Inflammation Markers and Modulate Gut Microbiota in Mice”
Authors: R.V. Espley, C.A. Butts, W.A. Laing, et al.