However, as most of these studies focused more on a potential health benefit from ingesting anthocyanins, studies that go in depth into these ingredients' prebiotic effect are still scarce and diffuse, said researchers from the Federal University of São Paulo in their study, published in the Journal of Food Composition and Analysis.
With the new influx of technology to better simulate digestion in vitro, they argued that it was necessary to review the present and main methods used to assess bioaccessibility of anthocyanins, the dark blue flavonoids that appear in fruits like açaí, grapes and blueberries. So far, existing preliminary and pilot studies suggest that the compounds may benefit those with obesity, pre-diabetes, or high cholesterol.
Understanding the mechanisms of anthocyanins linked to their bioaccessibility and bioavailability, leads to a better understanding of their beneficial health properties, as well as open up different applications of anthocyanins in the health food and supplement industries, they added.
The researchers collected studies that addressed bioaccessibility and bioavailability of anthocyanins, both experimental studies and other reviews, through the ISI Web of Knowledge and Medline databases.
To be included, an article had to be published in English from the years 2000 to 2017, and performed with in vitro, ex vivo and in vivo methods. The 35 remaining studies were pooled and synthesized to extract data on current scientific understanding of anthocyanins.
The prebiotic effect
They found that many of the studies attributed anthocyanin metabolism to gut microbiota. “For this reason, some authors have postulated that anthocyanins have a prebiotic effect,” the researchers wrote.
For example, in two different studies, the ingestion of anthocyanin-rich food amplified the amount of Bifidobacterium spp. Moreover, the microbiota of living organisms (like rats and humans) possess an enzymatic system that, when anthocyanins are metabolized, may produce compounds with different biological activities.
The biggest difficulty in capturing the mechanism, however, is the lack of a standardized method to assess bioaccessibility and bioavailability. Synthesizing the studies were difficult because in vitro methods fail to consider the role of individual microbiota in the human body, the researchers said.
Fermentation to formulate anthocyanins products with health benefits
Based on the reviewed studies, the researchers suggested that food formulators account for gut microbiota changes from one individual to the other by incorporating it in fermented products.
“Since more recent studies have shown the importance of the interaction between the microbiota and anthocyanins, using the fermentation products as a tool to improve the pigments absorption could bring a way to promote their beneficial properties through the modulation of the individual gut microbiota,” they wrote.
Source: Journal of Food Composition and Analysis
Published online ahead of print, https://doi.org/10.1016/j.jfca.2017.07.031
Authors: Anna Rafaela Cavalcante Braga, Daniella Carissa Murador, Leonardo Mendes de Souza Mesquita, Veridiana Vera de Rosso