WASHINGTON — Low birth weight newborns who are breastfed for less than three months may be at higher risk later in life for heart disease and diabetes, according to a new study which measured levels of a biomarker of inflammation in young adults.
Researchers at Northwestern University in Evanston, Illinois analyzed data on levels of an inflammatory marker called c-reactive protein, or CRP, in a large group of young adults, ages 24 to 32. The data were part of the National Longitudinal Study of Adolescent Health, sponsored by the U.S. National Institute of Child Health and Human Development.
Begun in 1994, the study is the most comprehensive, long-term health survey undertaken to date, following 7,000 teenagers in grades 7 through 12 for more than a decade. The project has spawned hundreds of peer-reviewed studies.
Thomas McDade, a professor of anthropology at Northwestern, is the lead author of the latest investigation, published in Proceedings of the Royal Society B: Biological Sciences.
He said young adults who were underweight as babies and those who were only breastfed for a few months, if at all, had higher levels of the inflammatory protein. Chronic inflammation is known to contribute to cardiovascular disease. The effect was the opposite for heavier babies or those that breastfed for longer.
“Higher birth weight babies and babies that are breastfed for longer periods of time will have lower levels of inflammation as adults, and that will reduce their risk for heart attack and other diseases of aging,” said McDade.
For each additional pound of birth weight, researchers found there was a 5 percent lower concentration of CRP. And c-reactive protein levels were 20 to 30 percent lower in young adults who had been breastfed for three to 12 months.
McDade said scientists do not know why that is. They suspect there’s something in human breast milk that bolsters the immune system.
Adult onset diabetes and heart disease have reached epidemic proportions worldwide. That increase followed many decades - during the middle to latter half of the last century - when formula feeding was encouraged.
McDade said many factors are involved in the development of heart disease and diabetes - including diet and genetics - and women today should not feel bad if they choose to use infant formulas.
“It puts a lot of responsibility and burden on women who already bear a heavy burden in our society in terms of their responsibility of taking care of our babies and our children. And we don’t want to do anything that places more blame on them or a higher level of responsibility. And they shouldn’t feel guilty if they decide not to, or can’t, breastfeed,” said McDade.
When measured against previous clinical studies, investigators found breastfeeding had the same or greater benefit as medications used to reduce c-reactive protein in young adults. They say the study results highlight the importance of promoting better pre-natal care and a longer period of breastfeeding as a way to improve public health.