Metabolic Fate of Blueberry Anthocyanins after Chronic Supplementation in Healthy Older Adults

Abstract

Plant derived anthocyanin rich foods play a protective role against chronic diseases such as diabetes, obesity, cardiovascular, cancer and neurodegenerative diseases. Anthocyanins are absorbed in their intact form and can be metabolized to a wide array of phenolic metabolites/conjugates. Blueberries are considered to be one of the richest source of anthocyanins and in the present study, we explored the metabolic fate of blueberry anthocyanins after chronic (90 days) supplementation of freeze‐dried blueberry (24 g/d, equivalent to 1 cup of fresh blueberries) in 19 healthy older adults (67.8 ± 4.6 y). Blood samples were collected at baseline (t=0 h) and 2 h post consumption on day 1 (no treatment), day 45 and day 90. A total of 28 anthocyanin metabolites were identified in plasma using ultra high‐performance liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometer. Peonidin glucuronide, a conjugated metabolite of peonidin, reached 204.5 ± 87.5 nmol/L at 2 h on day 45, which was the highest concentration among all phase II metabolites maintaining the parent structure. Among the parent untransformed anthocyanins, the content of malvidin galactoside was highest (37.4 ± 10.4 nmol/L) while the content of cyanidin glucoside was lowest (10.0 ± 2.9 nmol/L) in 2 h plasma sample on day 45. Out of 14 phenolic acid metabolites, the concentration of 7 metabolites were increased in baseline plasma at day 45 and 90 when compared to baseline plasma at day 1. The concentration of twelve phenolic acid metabolites increased at 2 h when compared to 0 h on day 45 and 90. Ferulic acid, vanillic acid, syringic acid and ferulic acid glucuronide were detected only in 2 h plasma samples. Our results suggest that blueberry anthocyanins are absorbed and extensively metabolized/catabolized resulting in the production of various phenolic acid derivatives and their conjugates, all together contributing to the bioavailability and beneficial effects associated with blueberry consumption.Support or Funding InformationU.S. Department of Agriculture, U.S. Highbush Blueberry Council, Tufts University and Investigator (Burton‐Freeman/Edirisinghe) various donor funds.