The study will be conducted as a randomized, double blind, placebo-controlled parallel trial. Subjects will be randomly assigned to either the Treatment (cranberry beverage) group or the Placebo group and each will be instructed to consume the test beverages twice a day for 70 days. The beverage is not commercially prepared juice, but is a beverage prepared with an extract of cranberry that contains polyphenols and proanthocyanidins. Blood is taken at baseline, and day 70. Subjects are given a diary to keep a record of their cold and flu symptoms. Serum is used to determine the antioxidant activity by the ORAC method. Peripheral blood mononuclear cells are isolated from the blood draw and used fresh, cultured for 24 hours or cultured for 10 days. Freshly isolated cells will be used to determine αβ-T, γδ-T, B and NK cell numbers and then cultured in autologous serum for 10 days to determine how well they proliferate. The supernatant of 24 hour cultures will be used for cytokine determination. If cells have been primed by the beverage made with cranberry compounds, the investigators expect the cells to proliferate to a greater extent and have modified cytokine production compared to placebo. If the beverage made with cranberry compounds enhances the proliferation of one or more of these cell types (αβ-T, γδ T, B or NK cell), then it is possible that there will be fewer cold and flu symptoms in the group consuming the cranberry beverage. Incidence of illness is not expected to change, only the severity of the illness.
The purpose of this study is to determine whether consuming a beverage made with cranberry polyphenols and proanthocyanidins is effective in modifying immune function by enhancing immune cell proliferation, cytokine production, and antioxidant capacity. If immune cell proliferation is improved, the subjects are expected to have fewer cold and flu symptoms.