Consumption of cranberry polyphenols enhances human γδ-T cell proliferation and reduces the number of symptoms associated with colds and influenza: a randomized, placebo-controlled intervention study

Abstract

Background: Our main objective was to evaluate the ability of cranberry phytochemicals to modify immunity, specifically γδ-T cell proliferation, after daily consumption of a cranberry beverage, and its effect on health outcomes related to cold and influenza symptoms.

Methods: The study was a randomized, double-blind, placebo-controlled, parallel intervention. Subjects drank a low calorie cranberry beverage (450 ml) made with a juice-derived, powdered cranberry fraction (n = 22) or a placebo beverage (n = 23), daily, for 10 wk. PBMC were cultured for six days with autologous serum and PHA-L stimulation. Cold and influenza symptoms were self-reported.

Results: The proliferation index of γδ-T cells in culture was almost five times higher after 10 wk of cranberry beverage consumption (p <0.001). In the cranberry beverage group, the incidence of illness was not reduced, however significantly fewer symptoms of illness were reported (p = 0.031).

Conclusions: Consumption of the cranberry beverage modified the ex vivo proliferation of γδ-T cells. As these cells are located in the epithelium and serve as a first line of defense, improving their function may be related to reducing the number of symptoms associated with a cold and flu.

Trial registration: ClinicalTrials.gov NCT01398150.

Figure 1

Flow diagram: Study participant eligibility assessment, enrollment, group allocation and analysis. People recruited for the study were assessed and those deemed eligible were enrolled. Subjects were randomized into one of two beverage groups. Bottles of the two beverages, cranberry and placebo, were received from Ocean Spray Cranberries, Inc. and labeled either #638 or #246. Subjects and investigators were blinded regarding the treatment groups. Statistical analysis was performed on data from all subjects completing the study. Investigators were unblinded (cranberry beverage: #638; placebo beverage: #246) following completion of the data analysis.