Tracy Postek

University of New Hampshire

Nutritional Science


Mentor: Dr. Gale Carey, Associate Professor of Animal & Nutritional Science

Effect of Maternal Exercise and Diet on Infant Acceptance and Composition of Human Breast Milk

The benefits of following a nutritious diet and exercise program are well known. However, much less is understood about these benefits for lactating women and their infants. Lactating women have been advised against exercise during lactation on the basis of one study. In addition, testimonials have led many lactating women to avoid dairy products in an effort to reduce infant colic, yet conjugated linoleic acid (CLA); a naturally occurring fatty acid found in dairy products, may provide protection from breast cancer and heart disease. The objectives of this study were (1) to determine the relationship between maternal consumption of foods containing CLA and the CLA content of breast milk and (2) to investigate the effects of moderate maternal exercise on infant acceptance and composition of breast milk.

Two lactating women followed a moderate dietary program containing 60% of calories from carbohydrate, 15% from protein and 25% from fat, in addition to recording their consumption of dairy and dairy by-products for approximately 1-2 weeks. Subjects visited the lab for 3 tests: a maximal oxygen consumption test (VO2max), a resting control test and a moderate (80% of VO2max) 30-minute exercise test.

Breast milk was collected via electric breast pump one hour prior to and one hour post-exercise or rest, measured for lactic acid (LA) content, placed in a bottle and fed to the infant by the mother. Pre- and post-exercise feeding sessions were videotaped for blind evaluation by lactation consultants.

Breast milk samples were freeze-dried and analyzed for CLA content. Dietary intake of carbohydrate, protein, fat, total calories and CLA was determined from food records.

The results showed no change in breast milk LA content or infant acceptance post-test compared to pre-test. The exercise findings are in agreement with previous research. CLA intake was variable; milk CLA content has yet to be determined. We conclude that moderate exercise poses no risk to mother or infant.

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