Introduction: Bee pollen is a natural substance obtained from flowers by bees. It is a rich source of protein, vitamins and minerals. It can be used as a dietary supplement. Bee pollen has been investigated for the treatment of some diseases with promising potential. It can be helpful in supportive therapy for dyslipidemia, metabolic syndrome, diabetes type 2, as well the prevention and control of coronary heart disease and myocardial infarction. Whey protein is a rich source of amino acids. It is a basic dietary supplement for many athletes, both professional and amateur. It stimulates muscle growth and provides nutrition for cachectic patients. Aim of the study: The objective of the study was to assess the impact of dietary supplementation of bee pollen or whey protein on the Wistar rat liver histological structure and expression of interleukin 12, smooth muscle actin and nitric oxide synthases among running and non-running rats. Material and methods: Thirty male Wistar rats were divided into six equal groups, three running and three non-running. Among both there was one control, one supplemented with bee pollen and one receiving whey proteins. After 8 weeks, all animals were decapitated and their livers were collected. Five micrometer thick slides were prepared and used for classical histological staining and immuno-histochemistry. ImageJ image analysis software was used to measure optical density and immunohistochemistry profile coverage. Results: Among all groups, morphology of liver was similar. In the running control group, expression of interleukin-12 (IL-12) was decreased as well as expression of endothelial nitric oxide synthase (eNOS) in a group of bee pollen supplemented rats. No significant changes in α- smooth muscle actin (α-SMA) expression was observed. Conclusions: Bee pollen is proving to be a questionable choice for athletes as an alternative to whey protein. Bee pollen supplementation affects hepatocyte cellular activity and has hepatoprotective effects. Whey protein performs worse in this regard. Lower antioxidant properties were found in groups supplemented with bee pollen than with whey protein. Keywords: bee pollen; whey protein; liver; interleukin-12; endothelial nitric oxide synthase; smooth muscle actin