Milk Enzyme Activities and Subclinical Mastitis Among Women in Guinea-Bissau

Background: Subclinical mastititis (SCM) is a condition with raised milk concentration of sodium and milk immune factors. The milk enzymes N-acetyl-beta-D-glucosaminidase ( NAGase), lactate dehydrogenase (LDH), acid phosphatase (AcP), and alkaline phosphatase (AP) have attracted attention in dairy research as indicators of SCM, udder health, and milk quality. Study Design: To investigate if milk enzyme activities and the inflammatory interleukin 8 (IL-8) level are increased in women with SCM, we measured sodium, potassium, NAGase, LDH, AcP, AP, and IL-8 in breast-milk samples collected at 2 months postpartum from 797 women in Guinea-Bissau, West Africa. Results: SCM, as indicated by a molar milk sodium/potassium ratio (Na/K ratio) greater than 0.6, was present in 26% of the women, and 9% had Na/K ratios larger than 1. The Na/K ratio was positively associated with NAGase, LDH, AcP, AP, and IL-8 in univariate linear regression (p < 0.001 for linear trend for all milk enzymes and IL-8). Conclusions: A positive association between the Na/K ratio and the breastmilk enzymes NAGase, LDH, AcP, and AP was found. Breastmilk enzymes have not previously been investigated in relation to SCM in women, and further research is warranted to highlight their specific role in the etiology of SCM.