Effects of Feeding A1 and A2 Cow Milk-based Diet on Hematological Parameters in Diabetic Mice Model

Background: Milk is essential part of diet across the globe and is a rich source of protein and calcium. Major protein component of milk is casein with beta-casein (β-casein) as the second most prevalent protein in cow milk. β-casein has 15 different genetic variants and of these A1 and A2 have gained research focus. All livestock as well as well human have proline at amino acid position 67 of β-casein, which is referred as A2 variant, but in cattle breeds, other genetic variant called A1 with histidine at amino acid position 67 is also present. This A1 type variant of β-casein or A1 type milk has been implicated as a potential etiological factor in several pathologies. Methods: The objective of the present study was to evaluate the A1and A2 β-casein variants of cow milk as factors affecting different hematological parameters and other parameters like glucose and insulin in streptozotocin (STZ)-induced diabetic C57/BL6 mice after the induction of diabetes. Diabetes was induced by injecting STZ intraperitoneally at dose of 45mg per kg of body weight for consecutive 5 days. Milk powder prepared from milk with A1A1 and A2A2 genotypes was used for feeding for three months. Result: After 3 months of feeding trial, it was observed that diabetic mice fed with A1A1 milk (STZ+A1A1) exhibited significantly elevated levels of glucose and insulin. Similarly, the levels of white blood cells, lymphocytes and neutrophils showed significant changes in STZ+A1A1 group compared to control and STZ+A2A2 group indicating the probable association A1A1 milk with inflammatory reaction. However, no significant changes were observed in parameters like red blood cells, hemoglobin, hematocrit or mean cell volume. In the mice group fed with A2A2 milk powder-based diet, no significant change was observed in the observed parameters except lymphocyte percentage which was lower compared to control group. In summary, our results show that A1 form of cow milk might have a proinflammatory effect.