Daily Intake of Probiotic as well as Conventional Yogurt Has a Stimulating Effect on Cellular Immunity in Young Healthy Women

Background/Aims: The aim of this work was to study the effects of daily yogurt consumption on the cellular immunity of young healthy women and to compare a conventional with a probiotic product. Methods: 33 young healthy women (22–29 years) consumed 100 g/day of either probiotic or conventional commercially available yogurt for 2 weeks and 200 g/day for another 2 weeks followed by a 2-week washout period with no fermented food at all. Before the intervention and after each phase, a complete white blood count was done, the percentage of activated CD69+ T lymphocytes after stimulation of whole blood with pokeweed mitogen was determined as well as the natural cytotoxicity of peripheral blood mononuclear cells against a human erythroleukemic target cell line (K562). All analyses were done by flow cytometry. Results: In the probiotic group only, the numbers of cytotoxic T lymphocytes (CD3+CD16+CD56+) increased significantly (+30.8% with p = 0.001, +22.1 and +32.7% with p = 0.002, for T2, T3 and T4 compared to T1). There were no major changes for other cell populations, and all remained within the physiological range. In both groups, the expression of CD69 on T lymphocytes increased after yogurt consumption, especially on CD8+ (conventional: T2 +23%, T3 +27.2%, probiotic: T2 +15.7%; T3 +10.8% compared to T1) and to a lesser extent on CD4+ (conventional: T2 +7.7%, T3 +14.9%, probiotic: T2 +4% compared to T1. The cytotoxic activity also augmented following the intake, this effect persisting after cessation of consumption. However, there were no significant differences between the probiotic and the conventional yogurt group. Conclusion: Daily yogurt intake has a stimulating effect on cellular immune functions, but in this study the probiotic product did not perform better than the traditional one.