Folsom, Calif – August 11, 2023 – A new study published in Scientific Reports finds that eating the equivalent of one daily cup of blueberries (containing 805 mg/day total phenolics and 280 mg/day total anthocyanins) for 14 days before and four days after a 90-minute eccentric exercise session reduced post-exercise markers of inflammation in adults who exercise fewer than three times per week.  The study was conducted at the Appalachian State University Human Performance Laboratory at the North Carolina Research Campus, Kannapolis, North Carolina.
Eccentric exercises such as running downhill or lowering weight cause extensive and prolonged muscle damage, soreness and inflammation particularly in individuals who do not regularly exercise.  Recovery from post-exercise inflammation is a complex process that can be assessed by measuring oxylipins, metabolites produced from oxidized fatty acids during stressful exercise. [3, 4] Emerging evidence suggests oxylipins are involved in initiating, mediating, and resolving exercise-induced muscle inflammation and can thus act as signaling agents of inflammation. 
Previous research found that daily blueberry consumption can help counter increases in proinflammatory oxylipins after exercise in trained endurance athletes. [3, 5] The purpose of this study was to assess if the same effect would be seen in untrained adults who exercise fewer than three times per week, dubbed “weekend warriors.”
This randomized, placebo-controlled, double-blinded clinical trial, “Blueberry Intake Elevates Post-Exercise Anti-inflammatory Oxylipins,” investigated the effects of blueberry supplementation on muscle soreness and inflammation resolution in 49 healthy, untrained adults ages 18 to 50 years (BMI less than 30 kg/m2) after 90-minutes of eccentric exercise.
Participants consumed either 25 grams of freeze-dried blueberry powder (equivalent to one cup of fresh blueberries) or a placebo (25 grams powder) daily for 14 days. After this period, participants engaged in a 90-minute eccentric exercise session. Participants continued blueberry or placebo supplementation during a 4-day post-exercise recovery period. Blood samples were collected before and after the 2-week supplementation, immediately post-exercise, and each morning during the 4-day recovery period. After blood draws, participants provided muscle soreness ratings and completed muscle function tests.
Results showed that while muscle soreness ratings, muscle function, and damage biomarkers did not differ between the blueberry and placebo groups, there were significant differences in oxylipin levels between groups. Those who consumed blueberries had higher levels of certain anti-inflammatory oxylipins (specifically, DHA- and EPA- derived HDoHE and SPM-intermediate oxylipins) and lower levels of pro-inflammatory markers (specifically, diHOMEs) during the 4-day post-exercise recovery period.
Though the exact mechanism remains unknown, researchers suggest the polyphenols in blueberries may play a role in enhancing levels of oxylipins by inducing changes in the gut microbiome, which may in turn influence oxylipin production through effects on related enzyme systems. Previous research has shown that anthocyanins from blueberries are metabolized into smaller molecules in the gut and prevent chronic inflammation by inhibiting production of proinflammatory mediators.  Several review papers support this, and have concluded that increased intake of blueberries, anthocyanins, and polyphenols in general may help mitigate exercise-induced muscle soreness, damage, and dysfunction. 
The data from 14 days before and four days after do not support a positive effect on muscle soreness and damage after one acute muscle-damaging exercising bout, however changes in muscle damage biomarkers following eccentric exercise are highly variable between individuals, and higher numbers of subjects in each group would be necessary to have sufficient statistical power and information to determine if blueberry ingestion influences muscle damage. In addition, the effects of a longer period of blueberry ingestion remains to be determined.
“Blueberry intake can be encouraged for physically active people to improve recovery from stressful levels of exercise,” said David Nieman, DrPH, FACSM, director of the Human Performance Lab at the North Carolina Research Campus and the study’s lead investigator. “Supporting recovery with an accessible whole food intervention, like blueberries, could increase compliance with exercise recommendations.”
Overall, the findings from this study, which was funded by the US Highbush Blueberry Council, suggest that diet plays an important role in the body’s response to exercise stress, and blueberries may be a particularly beneficial food for soothing post-exercise inflammation. Blueberries can be a specifically valuable addition to the diets of weekend warriors because of their anthocyanin and vitamin C content (241.7 mg and 14 mg per 148g serving, respectively) and because blueberry intake augments release of anti-inflammatory oxylipins. These findings are particularly relevant for adult “weekend warriors” who exercise fewer than three times per week and are prone to muscle inflammation post-workout.
The USHBC had no role in study design, data collection, data analysis, data interpretation, or writing of the study. For more information on blueberry nutrition research visit blueberrycouncil.org/health-professionals/health-research/
 Nieman, D, Sakaguchi, C.A., Omar, A.M., Davis, K.L., Shaffner, C.E., Strauch, R.C., Lila, M.A., Zhang, Q. Blueberry intake elevates post-exercise anti-inflammatory oxylipins: A randomized trial. Scientific Reports 13, 11976 (2023).
 Nieman D. et al. Almond intake alters the acute plasma dihydroxy-octadecenoic acid (DiHOME) response to eccentric exercise. Front. Nutr. 9, 1042719 (2023)
 Nieman, D. C. et al. Carbohydrate intake attenuates post-exercise plasma levels of cytochrome P450-generated oxylipins. PLoS ONE 14, e0213676 (2019).
 Gabbs, M., Leng, S., Devassy, J. G., Monirujjaman, M. & Aukema, H. M. Advances in our understanding of oxylipins derived from dietary PUFAs. Adv. Nutr. 6, 513–540 (2015).
 Nieman, D. C. et al. Blueberry and/or banana consumption mitigate arachidonic, cytochrome P450 oxylipin generation during recovery from 75-Km cycling: a randomized trial. Front. Nutr. 7, 121 (2020).
 Bouyahya, A. et al. Chemical compounds of berry-derived polyphenols and their effects on gut microbiota, inflammation, and cancer. Molecules 27, 3286 (2022).
 Avendano, E. E. & Raman, G. Blueberry consumption and exercise: Gap analysis using evidence mapping. J. Altern. Complement. Med. 27, 3–11 (2021).