Berry phenolics are associated with cognitive enhancement in blueberry- and strawberry-supplemented healthy older adults

Authors: Miller, Marshall; SANDHU, AMANDEEP - Illinois Institute Of Technology; Thangthaeng, Nopporn; SCOTT, TAMMY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; BURTON-FREEMAN, BRITT - Illinois Institute Of Technology; Shukitt-Hale, Barbara

Submitted to: Society for Neuroscience Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/22/2017
Publication Date: 11/11/2017
Citation: Miller, M.G., Sandhu, A.K., Thangthaeng, N., Scott, T.M., Burton-Freeman, B.B., Shukitt Hale, B. 2017. Berry phenolics are associated with cognitive enhancement in blueberry- and strawberry-supplemented healthy older adults. Society for Neuroscience Abstracts and Proceedings. Program #667.16.

Interpretive Summary:

Technical Abstract: The aging process often involves functional declines in cognition, leading to lower quality of life and increased need for care among older adults. Epidemiological evidence suggests that a diet rich in fruits and vegetables can reduce the risk of age-related cognitive impairment, in part due to the presence of antioxidant and anti-inflammatory phytochemicals in these foods, e.g., polyphenols. In recent double-blind, placebo-controlled clinical trials conducted by our laboratory, healthy older adults (ages 60-75) consumed 12 g of freeze-dried blueberry (equivalent to 1/2 cup blueberries) or strawberry (equivalent to 1 cup strawberries) twice daily for 90 days. In both studies, participants in the control groups consumed an equal amount of a seemingly identical, isocaloric placebo powder twice daily. Participants completed a battery of 8 cognitive tests and provided blood samples at baseline, and again following 45 and 90 days of intervention. Participants in the blueberry group showed enhanced executive function as evidenced by significantly fewer repetition errors in the California Verbal Learning test (CVLT-II; p = 0.031) and a reduced switch cost on a task-switching test (p = 0.033) across study visits, relative to placebo controls. Participants in the strawberry group showed enhanced learning and memory as evidenced by significantly improved probe trial performance in a virtual water maze during the midpoint visit (p = 0.020) and improved word recognition in the CVLT (p = 0.014). No significant effects were observed on the other tests. Plasma phenol concentrations, including both parent compounds and metabolites, were measured after an overnight fast and 2 hours postprandial at each time point (the standardized meal included supplement or placebo at 45- and 90-day visits). Levels of circulating polyphenolics, including anthocyanins, ellagitannins, and phenolic acids were significantly altered as a result of berry consumption. Results showed that blueberry and strawberry polyphenols were absorbed and extensively metabolized, resulting in the production of various phenolic acid derivatives and their conjugates. Regression analysis showed that changes in circulating levels of specific phenolic compounds were correlated with the observed changes in cognition. Therefore, the addition of easily achievable quantities of berry fruit to the diets of older adults can improve some aspects of cognition, likely due to increased levels of circulating berry phenolics and their metabolites.