|Sandhu, Amandeep - Illinois Institute Of Technology|
|Scott, Tammy - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|Edirisinghe, Indika - Illinois Institute Of Technology|
|Burton-freeman, Britt - Illinois Institute Of Technology|
Submitted to: Food & Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2017
Publication Date: 1/1/2018
Citation: Sandhu, A.K., Miller, M.G., Thangthaeng, N., Scott, T.M., Shukitt Hale, B., Edirisinghe, I., Burton-Freeman, B. 2018. Metabolic fate of strawberry polyphenols after chronic intake in healthy older adults. Food & Function. 9:96-106.
Interpretive Summary: Strawberries may help to reduce the risk of age-related diseases due to a group of compounds known as polyphenols. Strawberry polyphenols are absorbed and metabolized in the gut, transforming them into slightly different molecules, the “polyphenolic metabolites,” which are believed to exert strawberry’s health-promoting effects. In the present study, we investigated the metabolism of strawberry polyphenols after a 90-day supplementation of a beverage made with freeze-dried strawberry vs placebo powder in 19 healthy older adults. We hypothesized that a large percentage of the total strawberry polyphenols would be metabolized and quickly cleared from the body in urine. Blood samples were collected at day 0 and days 45 and 90; on each day, blood was collected at two time points: before breakfast (fasting), and 2 hours after placebo or strawberry drink with breakfast. A total of 20 polyphenolic metabolites were quantified in blood plasma; the most prevalent metabolites were different for the strawberry and placebo groups. Almost all of the strawberry metabolites were detected not only at the 2-hour post-meal time point, but also at the fasting time point on days 45 and 90. Our results suggest that strawberry polyphenols are absorbed and extensively metabolized, and are far more longer-lasting than previously realized.
Technical Abstract: Strawberries are considered a functional food due to the presence of a wide array of nutrients and phytochemicals including polyphenols such as anthocyanins, procyanidins and ellagitannins. These polyphenols are absorbed and metabolized to various phenolic metabolites/conjugates in the body which may play a role in disease risk reduction. In the present study, we investigated the metabolic fate of strawberry polyphenols after chronic (90 days) supplementation of freeze-dried strawberry (24 g/d, equivalent to 2 cup of fresh strawberries) vs placebo powder in 19 healthy older adults. Blood samples were collected at two time-points, i.e., fasting (t=0 h) and 2 h post placebo or strawberry drink with breakfast on day 0 (no treatment), and days 45 and 90 depending on treatment randomization. A total of 20 polyphenolic metabolites were quantified in plasma consisting of 3 anthocyanins/metabolite, 2 urolithin A glucuronides and 15 phenolic acid metabolites. Among anthocyanins/metabolites, pelargonidin glucuronide (85.7 ± 9.0 nmol/L, t=2 h, day 90) was present in the highest concentration. Hippuric acid (25.7 umol/L, t=2 h, day 45) was the most abundant phenolic acid derivative present in plasma of both placebo and strawberry group. The persistence in the concentrations of anthocyanins/metabolites, urolithins and some phenolic acids was observed in fasting (t=0 h) plasma samples on day 45 and 90 suggesting a role of enteric, enterohepatic recycling or upregulation of gut microbial and/or human metabolism of these compounds. Our results suggest that strawberry polyphenols are absorbed and extensively metabolized, and are far more persistent than previously realized.