Healthy volunteers consumed 300 mg green tea extract for 14 days and whole blood was obtained and studied for its antioxidant capacity, in this study published in 2015. After 14 days of green tea extract consumption, there was a significant increase in the release of myeloperoxidase and lactoferrin when whole blood was stimulated with fMet-Leu-Phe, which activates a number of leukocytes including mature neutrophils and monocytes.
References:
Lowe, G. M., Gana, K., & Rahman, K. (2015). Dietary supplementation with green tea extract promotes enhanced human leukocyte activity. Journal of complementary & integrative medicine, 12(4), 277–282. https://doi.org/10.1515/jcim-2014-0042
