Blueberry phenolics are associated with cognitive enhancement in healthy supplemented older adults

Authors: Rutledge, Grant; SANDHU, AMANDEEP - Illinois Institute Of Technology; MILLER, MARSHALL - Duke University; EDIRISINGHE, INDIKA - Illinois Institute Of Technology; BURTON-FREEMAN, BRITT - Illinois Institute Of Technology; Shukitt-Hale, Barbara

Submitted to: Food and Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2020
Publication Date: 12/15/2020
Citation: Rutledge, G.A., Sandhu, A.K., Miller, M.G., Edirisinghe, I., Burton-Freeman, B.B., Shukitt Hale, B. 2020. Blueberry phenolics are associated with cognitive enhancement in healthy supplemented older adults. Food and Function. 12:107-118. https://doi.org/10.1039/D0FO02125C.
DOI: https://doi.org/10.1039/D0FO02125C

Interpretive Summary: Blueberries contain polyphenol compounds that may play a protective role against chronic age-related diseases. Polyphenols are micronutrients that we get through certain plant-based foods, and they have been shown to have health benefits. Here we explored the blueberry-derived polyphenol compounds that were found in the blood of 19 healthy older adults after 90 days supplementation with freeze-dried blueberry. Blood samples were collected at day 0, 45, and 90, and various tests of brain function were also conducted on those days. The levels of 11 polyphenol compounds were increased in the blood as a result of blueberry supplementation. Furthermore, individual differences in test performance were found to be related to changes in the levels of different polyphenol compounds in their blood. These findings show that blueberry in the diets of older adults can improve brain function, and improvements are related to changing levels of circulating blueberry-derived polyphenol compounds.

Technical Abstract: Blueberries contain an array of bioactive phenolic compounds that may play a protective role against chronic age-related diseases. Here we explored the metabolic fate of blueberry polyphenols 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, and a battery of cognitive tests was also conducted on these days. Hippuric acid, phloroglucinaldehyde, syringic acid, ferulic acid-glucuronide, cyanidin-3-galactoside, cyanidin-3-glucoside, malvidin-3-galactoside, malvidin-3-glucoside, peonidin-3-xyloside, peonidin glucuronide, and petunidin-3-glucoside concentrations were significantly altered as a result of blueberry consumption. Regression was used to assess the relationship between significantly altered concentrations of plasma phenolics and observed improvements in cognition. Among participants in the blueberry group, changes in switch errors from baseline to 90 days were associated with changes in postprandial levels of plasma ferulic acid-glucuronide, syringic acid, and malvidin-3-galactoside (R2 = 0.521, p < 0.014). Changes in CVLT-II repetition errors, from baseline to 90 days, were associated with changes in postprandial levels of ferulic acid-glucuronide, syringic acid, and hippuric acid (R2 = 0.807, p < 0.001). These findings show that the addition of easily achievable quantities of blueberry to the diets of older adults can improve some aspects of cognition, and improvements are related to changing levels of circulating phenolics.