Purple Vegetables and Tubers May Reduce the Risk of Type 2 Diabetes

Anthocyanins, the red, purple, and blue pigments found in fruits, vegetables, and tubers, have been shown to reduce the risk of type 2 diabetes by affecting energy metabolism, gut microbiota, and inflammation, according to a new review  from the Food Sciences unit of the University of Turku, Finland. 

The review compared research results on this topic and found that the beneficial effects of anthocyanins are increased when they are acylated, which takes place when an acyl group is added to the sugar moieties of anthocyanin. 

 Purple potatoes, purple sweet potatoes, radishes, purple carrots, and red cabbages are significantly high in anthocyanins, while bilberries and mulberries primarily contain nonacylated anthocyanins. Despite the limited absorption of acylated anthocyanins during digestion, their probiotic properties and superior efficacy in reducing the risk of diabetes warrant attention compared to their nonacylated counterparts.

"The studies have shown that, in addition to changing physical and chemical properties, the acylation affects how the anthocyanins are absorbed and metabolized," said chief researcher Kang Chen. 

Acylated anthocyanins are more effective antioxidants than nonacylated anthocyanins and can also improve the intestinal barrier and maintain gut microbiota homeostasis, suppress pro-inflammatory pathways, and modulate glucose and lipid metabolisms, said Chen.  

Different glucose transporters are responsible for the absorption of acylated and nonacylated anthocyanins, and they also have other impacts on the enzymes involved in metabolism. Recent research has shown that acylated and nonacylated anthocyanins can impact type 2 diabetes differently. Chen notes that the plant's genotype determines what kind of anthocyanins it produces. In general, purple vegetables contain many acylated anthocyanins, with the Finnish variety 'Synkeä Sakari' being particularly abundant in them.

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