New study reported in the Feb. issue of Pediatrics.

Enjoy!

Kathy

Effect of Exercise on Immunologic Factors in Breast Milk 

Objective. Although it is well documented that breast milk provides optimal 
nutrition and immune benefits to the infant, factors that influence the 
immunologic composition of breast milk are less understood. A recent study 
reported that immunoglobulin A (IgA) levels in breast milk are lower after 
exercise compared with resting concentrations. However, the women exercised 
until exhaustion. The effect of moderate exercise on immunologic components 
in breast milk has not been reported. Therefore, the purpose of this study 
was to 1) compare the levels of immunologic compounds in breast milk of 
exercising women with the milk of sedentary women and 2) determine whether 30 
minutes of moderate exercise affects immunologic properties of breast milk. 

Methods. Exclusively lactating women were studied at 3 months’ postpartum. 
Women in the exercise group (EG; n = 29) reported exercising aerobically at 
least 30 minutes/d for 3 days/wk, and women in the sedentary group (SG; n = 
24) had exercised once a week or less during the previous 6 weeks. 
Cardiovascular fitness levels and concentrations of IgA, lactoferrin, and 
lysozyme in milk were measured. A subsample of the EG (n = 17) participated 
in a 30-minute exercise session at 75% of maximum heart rate and a rest 
session of 30 minutes of sitting rest on 2 separate days. Breast milk samples 
were collected before and 10 and 60 minutes after exercise and rest sessions. 
IgA, lactoferrin, and lysozyme concentrations were measured. 

Results. Women in the EG had a higher level of cardiovascular fitness than 
women in the SG (39.7 ± 1.0 vs 32.4 ± 1.0 mL O2/kg/min). Milk concentrations 
of IgA, lactoferrin, or lysozyme were not significantly different between 
groups. In addition, there were no significant differences in the 
concentrations of IgA, lactoferrin, or lysozyme after moderate exercise 
compared with sitting rest. 

Conclusion. Moderate exercise during lactation improves cardiovascular 
fitness without affecting levels of IgA, lactoferrin, or lysozyme in breast 
milk. 

http://www.pediatrics.org/cgi/content/abstract/111/2/e148?etoc



Kathleen Fallon Pasakarnis, M.Ed. IBCLC
Nurturing Family Lactation and Parenting Services

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