Low-fat yogurt consumption maintains biomarkers of immune function relative to nondairy control food in women with elevated BMI: A randomized controlled crossover trial

Yogurt consumption may help reduce chronic inflammation associated with obesity. However, the underlying mechanism(s) by which yogurt consumption modulates the immune system have not been validated in human intervention studies. We hypothesized that 4-week yogurt consumption (12 oz/day) attenuates systemic inflammation by modulating the proportion of circulating T helper (Th) 17 and regulatory T (Treg) cells in adult women with elevated body mass index (BMI). To test the hypothesis, we conducted a randomized crossover dietary intervention study consisted of a 4-week dietary intervention in which participants consumed 12 oz of either low-fat dairy yogurt or a soy pudding control snack per day, with a 4-week washout between treatments. Thirty-nine healthy adult women with a BMI between 25 and 40 kg/m² were enrolled and 20 completed the study. Changes in the biometrics, circulating T cells, and markers of systemic and colonic inflammation were assessed between the 2 treatment groups, as well as 24-hour diet recalls were conducted at baseline and following each treatment. The primary study outcome, the change in the proportion of circulating Th17 cells, was unaffected by the treatments. Secondary outcome measures, circulating Treg, Th17, and markers of chronic inflammation, were maintained by yogurt treatment, whereas circulating Treg was increased and interleukin-10 was reduced by control snack treatment. However, circulating Treg changes were not associated with changes to other biomarkers of inflammation, implying other immune cells and/or tissues may mediate circulating biomarkers of chronic inflammation. This study was approved by the University of Wisconsin-Madison institutional review board and registered at ClinicalTrials.gov NCT04149418.