Anthocyanins in purple vegetables and tubers can reduce diabetes risk: Study

Finland: A new review article published in the Journal of Agricultural and Food Chemistry has shown the increase in the beneficial effect of anthocyanins on type 2 diabetes if anthocyanin is acylated, meaning that an acyl group is added to the sugar moieties of anthocyanin.

The red, purple and blue pigments in fruits, vegetables, and tubers called anthocyanins can reduce the risk of diabetes by affecting energy metabolism, gut microbiota, and inflammation.

A great number of acylated anthocyanins can be found in purple potatoes, sweet potatoes, radishes, purple carrots and red cabbages, whereas bilberries and mulberries contain mostly nonacylated ones anthocyanins. Acylated anthocyanins are poorly absorbed in digestion, but they have probiotic properties and reduce the risk of diabetes more efficiently than nonacylated anthocyanins.

“The studies have shown that, in addition to changing physical and chemical properties, the acylation affects how the anthocyanins are absorbed and metabolised,” says Postdoctoral Researcher Kang Chen at the Food Sciences Unit, University of Turku, Finland.

The acylated anthocyanins are more effective antioxidants than the nonacylated anthocyanins, and they can also improve the intestinal barrier that enables the absorption of necessary nutrients. Furthermore, the acylated anthocyanins maintain gut microbiota homeostasis, suppress pro-inflammatory pathways, and modulate glucose and lipid metabolisms.

“The plant's genotype defines what kind of anthocyanins they produce. In general, purple vegetables contain many acylated anthocyanins. Also, purple potatoes, especially the Finnish variety called ‘Synkeä Sakari’, is abundant in acylated anthocyanins,” says Chen.

Acylated anthocyanins travel through our bodies from the upper gastrointestinal tract to the colon, where the gut microbiota metabolises them. Glucose transporters are involved in anthocyanin absorption, but different glucose transporters are responsible for the absorption of acylated and nonacylated anthocyanins. The acylated and nonacylated anthocyanins also have different impacts on the enzymes involved in metabolism.

“The latest research has shown that the acylated and nonacylated anthocyanins can impact type 2 diabetes in different ways,” Chen summarises.

Reference:

Kang Chen, Maaria Katariina Kortesniemi, Kaisa Marjut Linderborg, and Baoru Yang Journal of Agricultural and Food Chemistry 2023 71 (2), 1002-1017 DOI: 10.1021/acs.jafc.2c05879