Stewart, Laura K.
College of Natural and Health Sciences;Exercise Physiology
University of Northern Colorado
Type of Resources
Place of Publication
University of Northern Colorado
Cancer is one of the most prevalent diseases affecting society today, and the number of newly diagnosed cases increases every year. Unresolved inflammation is an important underlying cause of cancer and chronically elevated concentrations of inflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor (TNF-α), and C-reactive protein (CRP) are positively related to cancer incidence and progression. Cancer treatments like chemotherapy and radiation therapy can impair beneficial gut microbes that help to protect against pathogens and modulate immunity. Physical activity and exercise regimens improve chronic inflammation and gut microbes in cancer survivors but relatively few studies have explored the potential for nutrition to further exacerbate the positive immunomodulating effects of exercise. Kefir is a fermented diary product that contains a variety of probiotics and has the potential to help physically active cancer survivors. However, the potential for kefir to improve chronic inflammation in cancer survivors who are enrolled in a structured exercise program has not been explored. The purpose of this study was to investigate the effects of 12 weeks of kefir supplementation during a supervised structured exercise program in cancer survivors. Nineteen cancer survivors 40 to 80-years-old who were enrolled in a structured exercise program and had undergone chemotherapy or radiation therapy within the past two years were separated into kefir (KEF) or control (CON) exercise treatment groups. All participants underwent 12 weeks of three days per week structured aerobic and resistance exercise training and the kefir group drank eight ounces of kefir following each exercise session. Each participant visited the test site three times at the pre-intervention time point and three times at post-intervention time points in addition to the 12 weeks of exercise training. Visits included assessments of body size and composition, aerobic fitness and muscular strength, medical history, psychological state, dietary assessments, and blood collection. Blood was analyzed for serum CRP, IL-6, and lipopolysaccharide (LPS) concentrations, and stimulated with LPS in culture to evaluate whole blood IL-6 and TNF-α production. Samples were prepared for flow cytometry analysis of monocyte number and percentage as well as monocyte phenotype. When both the KEF and the CON groups were combined, participants had high body fat percentages (36.4 ± 8.1%) prior to the intervention; a time by group interaction was observed where the KEF group experienced a significant 10.7% reduction in body fat by the post-intervention time point (p = .019); no change was observed in the CON group post-intervention. Furthermore, there was a main effect for time and a time by group interaction observed in lean body mass where the CON group significantly improved lean body mass (p = .002) but the KEF group improved lean body mass beyond the improvement observed in the CON group (p = .014). A significant main effect for time was observed where when both KEF and CON groups were combined, there were significant improvements with respect to aerobic fitness (p = .0.001), chest press strength (p = .027), lat pulldown strength (p = .000), and leg press strength (p = .015) at the post-intervention time point. A main effect for time revealed improvements in scores on the Beck Depression Inventory (p = .08), Piper Fatigue Scale (p = .002) and gastric distress survey (p = .013) when both KEF and CON groups were combined. In addition, a significant time by group interaction was observed post-intervention where the KEF group experienced reductions in fatigue (p = .002) and gastric distress (p = .021) beyond that observed in the CON group. Additionally, a time by group interaction was observed where the KEF group experienced significant reductions in serum concentrations of LPS (p = .0137) and LPS stimulated IL-6 production (p = .034) by the pre-intervention time point, while the CON group experienced no change. Furthermore, a significant main effect for time was observed; when both KEF and CON groups were combined, there was a significantly reduction in LPS-stimulated TNF-α production (p = .022). A significant time by group interaction was observed in the KEF group where percent of monocytes that were classical significantly increased (p = .016) and percent of monocytes that were non-classical significantly decreased (p = .016) compared to the CON group by the post-intervention time point. Moreover, a main effect for time was observed where when both KEF and CON groups were combined, there was a significant reduction in the percent of monocytes that were intermediate (p = .02) at the post-intervention time point. Twelve weeks of supervised exercise training significantly improved VO2Peak, muscular strength and lean body mass in all participants. In addition, a significant time by group interaction was observed where the KEF group experienced a significant body fat percent reduction and an increase in lean body mass when compared to the CON group. Both the kefir group and exercise control significantly improved depression and fatigue by the end of the exercise intervention while the kefir group improved fatigue beyond that of exercise control. Moreover, both groups significantly improved gastric distress over the course of the intervention but kefir supplementation resulted in a greater reduction in GI distress. Both the kefir and control groups experienced reductions in stimulated Il-6 production per monocyte by the post-intervention time point and kefir supplementation reduced overall stimulated IL-6 production beyond the reduction observed in the control group. Furthermore, both groups experienced reductions in stimulated TNF-α by the post-intervention time point. While it has been established that exercise training could help to improve many aspects of the lives of cancer survivors, kefir appeared to be well-tolerated and had the potential to improve immune function and fatigue beyond the benefits of a chronic exercise intervention alone. Including nutritional support with kefir as a post exercise nutrition strategy might be what cancer rehabilitation programs should consider in the future.
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