Study Reveals Breast Milk Contains More Than 700 Types of Bacteria

December 7, 2014

Mom’s Weight and Hormonal State During Birth Also Affect Number of Species Found, Researchers Say

Researchers in Spain have concluded that while breast milk contains many more types of bacteria than previously thought — more than 700 to be exact, a new study published in the “American Journal of Clinical Nutrition” this month also reveals that overweight mothers, and those who experienced more than the recommended weight gain, had fewer species present.

Additionally, women who had planned cesarean-section deliveries had fewer species present than those who had a vaginal birth. Mothers who had an unplanned, or emergency, C-section had about the same number of species of women who gave birth vaginally.

The findings imply that a woman’s hormonal state while giving birth affects the number of bacteria found in their breast milk, which is shown to later affect the amount of bacteria in a child’s digestive system.

The researchers will continue to study whether bacteria in breast milk aids in the formation of the child’s immune system, or if the bacteria helps babies digest the breast milk, or both.

“If the breast milk bacteria discovered in this study were important for the development of the immune system, its addition to infant formula could decrease the risk of allergies, asthma and autoimmune diseases,” said researcher Raul Cabrera-Rubio and his colleagues in the study notes.

Find out more from the U.S. Office on Women’s Health at

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