Effects of Kefir Consumption on Health Outcomes: Gastrointestinal System, Immunity, Biochemical Parameters, Body Composition, Sleep Quality and Mental Well Being in Healthy Adults

The goal of this clinical trial is to evaluate the effects of the administration of kefir on gastrointestinal system, mental health, biochemical parameters, immunity and inflammation processes as well as the sleep quality, elucidating the possible health effects of kefir consumption in healthy adults. The main questions it aims to answer are: 1. Will be better the gastrointestinal system symptoms severity of volunteers in the intervention group will be better compared to the control group? 2. Will be better the mental health status of volunteers in the intervention group will be better compared to the control group? 3. Will be better the biochemical parameters of volunteers in the intervention group will be better compared to the control group? 4. Will be better the immunity and inflammation processes of volunteers in the intervention group will be better compared to the control group? The participants were asked to consume 250 mL of plain lactose-free kefir daily for 6 weeks. Any particular time was not specified for kefir consumption. Kefir consumption routine of participants was followed up by regular phone calls every week and evaluated by examining their consumption records. Those who consumed less than 85.0% (skipping kefir consumption maximum once a week) of the planned kefir consumption during the study period were excluded from the study.