Understanding the Digestion and Health Impacts of Anthocyanins in Food

Yue, Yang (2024) Understanding the Digestion and Health Impacts of Anthocyanins in Food. Doctoral thesis, University of East Anglia.

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Abstract

Many studies have reported health-promoting effects including anti-inflammatory activity of dietary anthocyanins, both in vitro and in vivo. However, the mechanism(s) of action is less well-understood because of many factors that limit conclusions. One is the lack of near-isogenic genetic materials given the absence of non-coloured variants of the fruits and vegetables commonly used in intervention studies. The innovation of genetically modified purple tomatoes provided a unique opportunity to study the effects of dietary anthocyanins in comparison to control, red tomatoes, which lack anthocyanins. The original study found that a purple tomato-supplemented diet extended the lifespan of cancer-prone p53 knockout mice by 30% but the mechanism of action of the purple anthocyanins was not explored.

This thesis investigated the impact of dietary anthocyanins, using healthy mice and mice with low-grade inflammation fed red (control) and purple tomato-supplemented diets, and healthy mice fed coloured-flesh and white potato (control)-supplemented diets, through the lens of the intestinal microbiota and their metabolites derived from their interactions. For example, secondary bile acids, short-chain fatty acids, and tryptophan-derived metabolites, especially indole and indole derivatives were analysed. Consumption of dietary anthocyanins invoked changes in the microbiota and metabolites in healthy mice fed on the purple tomato, red potato and purple potato-supplemented diets. In addition, dietary anthocyanins appeared to invoke changes that could protect against inflammation in the gut and brain of mice which were challenged by LPS injection.

This thesis addressed two frequently overlooked issues with anthocyanin related studies: (1) both in vitro and in vivo studies showed that not all dietary anthocyanins act in the same way. Purified anthocyanins from the red potatoes increased the resistance of cooked starch to digestive enzymes (in vitro) and red potato diets decreased the body weight of male mice significantly, compared to extracts from purple potatoes (in vitro) and purple-potato-supplemented diets (in vivo); (2) the food matrix impacts the digestion of anthocyanins. The comparison of microbiota between mice fed on the purple tomato diets and purple potato diets showed that a starchy matrix can increase the diversity of the microbiota and promote the relative abundanceof beneficial bacterial species to maintain gut health. These results should be validated by human studies, to provide robust recommendations for anthocyanin consumption, and to honour the promise “let food be thy medicine and medicine be thy food.”

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	27 Mar 2025 11:30
Last Modified:	27 Mar 2025 11:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98891
DOI:

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