Lactose in human milk is associated with lower rates of infection during a drought.

Background: Infants given mothers' milk have higher resistance against infections than formula-fed counterparts. This protection is likely multifactorial, with roles for both milk immune factors and nutrients, particularly under elevated nutritional and disease stress.

Aim: This study evaluated several milk nutrients/immune factors to assess associations with infant infectious disease during a severe drought.

Subjects and methods: The study analysed morbidity recall data from Kenyan mother-infant dyads surveyed during a historic drought (n 84). Predictors of interest in logistic regression models of infant infections included milk sIgA, lactoferrin, retinol, folate receptor-α, fat, protein, and lactose. Adjustment variables included dyadic demographic characteristics and maternal infection. Akaike Information Criterion guided model fit assessment. Interactions between variables were allowed in the best-fit model.

Results: In the best-fit model, lactose was inversely (OR 0.93; 90% CI 0.89, 0.97), and maternal infection was positively (OR 2.80; 90% CI 1.04, 7.52) associated with infant infection. Milk immune factors (sIgA, lactoferrin) were not included in the final models.

Conclusion: Mothers' milk may protect infants against infection through a broad range of immune and nutrient components. In the context of severe drought with heightened nutritional and disease stress, lactose may protect against infection or decrease in the presence of an infection.