Breastfeeding is associated with reduced risk of multiple sclerosis in males, predominantly among HLA-DRB1*15:01 carriers

Abstract

Background Breastfeeding as an infant appears protective against later development of some autoimmune diseases, but research into its influence on multiple sclerosis (MS) risk has yielded inconclusive results. Objective We investigated the possible impact of breastfeeding on MS risk. Methods We used two population-based case–control studies comprising 3670 cases and 6737 matched controls. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for association between MS and exposure to prolonged breastfeeding (4 months or longer) versus reduced breastfeeding (less than 4 months). A meta-analysis of case–control studies that assessed the impact of breastfeeding on MS risk among women and men was conducted. Results Prolonged breastfeeding was associated with reduced MS risk among men (OR 0.7, 95% CI 0.5–0.9) but not among women (OR 0.9, 95% CI 0.8–1.1). Among men, a synergistic effect was observed between HLA-DRB1*15:01 carrier status and reduced breastfeeding. Conclusions Findings from the current study add to accumulating evidence that breastfeeding may be a modifiable protective factor for reducing the risk of MS in offspring. When possible, mothers should be supported to breastfeed their infants; however, the mechanism of a sex-specific biologic effect of breastfeeding on MS risk is unclear.

Cytomegalovirus seropositivity is associated with reduced risk of multiple sclerosis—a presymptomatic case–control study

“…Viral reactivation and viral shedding in breast milk occur for over 90% of seropositive mothers, which leads to subclinical infection of many infants [38]. Accumulating evidence indicates that breastfeeding may reduce the risk for MS in the offspring [39,40]. Considering the results from the present study, the transmission of CMV through breast milk could contribute to the observed risk reduction for MS in individuals that were breastfed.…”

What Can We Learn from Sex Differences in MS?

“…There is also a study indicating that breastfeeding may lower the infant's risk for MS [58]. Another study found a lowered risk in male infants, with a synergistic effect of HLA-DRB1*15:01 [59].…”

Risk Factors from Pregnancy to Adulthood in Multiple Sclerosis Outcome

“…At the same time, maternal illness, cesarean delivery, birth weight, and socioeconomic status influence the risk of pediatric onset of MS [105,106]. Moreover, it was observed that male patients carrying the HLA-DRB1*15:01 polymorphism who were breastfed for four months or longer have a reduced risk of MS development [107,108]. In fact, breastfeeding provides bidirectional benefits by lowering the risk of developing multiple sclerosis in both the child and the mother [109].…”