Background – Selenium (Se), an essential micronutrient, is incorporated into cells and proteins of the immune system, boosting immune function. Incorporation of micronutrients into biological materials (fortification), is proposed to improve micronutrient absorption. Recently technologies have been developed to increase the incorporation of micronutrients into cow’s milk.
Objective – To determine the dose-response relationship between 25, 73 and 121 μg Se /100g diet and blood selenium concentrations and immune function in healthy 3 month old mice.
Design – Three month-old mice were housed 3-per box and fed non-fortified milk protein (MP, 18 μg Se /100g total diet) and 3 Se-fortified MP diets (25, 73 and 121 μg Se /100g total diet), combined with normal mouse chow. The fortification was achieved by feeding Se enriched diets, allowing greater incorporation of Se into the cow’s milk proteins. All mice were vaccinated against Mem71 strain influenza virus at 21 d, and euthanised at 49 d, peripheral blood was then collected via cardiac puncture and the spleen removed. In blood, Se concentrations and the immune enzyme glutathione peroxidase (GPx) were measured. In the spleen, non specific proliferative capacity and Mem71 virus-specific proliferation were measured.
Outcomes – Blood Se concentrations increased linearly with increasing dietary Se concentration (P<0.001). This corresponded with increasing red blood cell GPx activity. Splenocyte proliferative capacity increased with 73 and 121 μg Se /100g diet compared to non-supplemented control, but the virus specific proliferation was highest when supplemented to 121 μg Se /100g diet.
Conclusion – Increasing Se fortification of cow’s milk linearly increased peripheral selenium concentrations, with corresponding improvement in immune function in healthy mice.