November 12, 2018Pediatrics
According to a study published online in the journal Human Reproduction (9 November 2018), results suggest that infant girls fed soy formula are more likely to develop severe menstrual pain as young adults. The finding adds to the growing body of literature that suggests exposure to soy formula during early life may have detrimental effects on the reproductive system.
For the study, data was examined from 1,553 African-American women, aged 23-35, participating in the NIEHS Study of Environment, Lifestyle, and Fibroids (SELF). Results showed that women who had ever been fed soy formula as babies were 50% more likely to have experienced moderate or severe menstrual discomfort between the ages of 18 and 22, and 40% more likely to have used hormonal contraception to help alleviate menstrual pain. The authors offered a potential explanation for the association between soy formula and severe menstrual pain. Data from previous laboratory animal studies suggest that early-life exposure to genistein, a naturally occurring component in soy formula, interferes with the development of the reproductive system, including factors involved in menstrual pain. These studies have also shown that developmental changes can continue into adulthood. However, severe menstrual pain is not the only adverse reproductive health condition that was linked to infant soy formula. Previously data have linked soy formula feeding to endometriosis, a condition where tissue that normally lines the inside of the uterus grows outside. Using SELF data, a link has also been shown with infant soy formula to larger fibroids among woman with fibroids, and to heavy menstrual bleeding. The only other research that evaluated soy formula in relation to menstrual pain was published in 2001 by scientists at the University of Pennsylvania, Philadelphia, and the University of Iowa, Iowa City. The study, which primarily included white young adults who participated in feeding studies when they were infants, also found an association between soy formula feeding and severe menstrual pain in the women. According to the authors, the results of both studies indicate that the findings may apply to all women, but further research is warranted before any changes are made to soy formula feeding recommendations.
The American Academy of Pediatrics (AAP) promotes human milk as the ideal source of nutrition for infants. It does not recommend soy formula for babies born prematurely. For full term infants, the AAP recommends soy formula in rare cases where the child's body cannot break down the sugars in milk or if the family prefers a vegetarian diet.