Babies of low birth weight and those who are never breastfed - or only breastfed for under 3 months - are more likely to grow into young adults with levels of chronic inflammation that can contribute to heart disease and metabolic disorders, warns a new study.
Researchers from Northwestern University in Evanston, IL, report their findings in the Proceedings of the Royal Society B: Biological Sciences.
In their study background, they note that while we already know higher blood levels of C-reactive protein (CRP) are a key biomarker of inflammation, and predict increased cardiovascular and metabolic disease risk in adulthood, we know little about the developmental factors that influence inflammation.
Using data from the National Longitudinal Study of Adolescent Health (Add Health), they evaluated levels of CRP in nearly 7,000 young adults aged from 24 to 32, and linked them back to their birth weight and how long they were breastfed for, if at all.
The study is particularly interesting because the researchers compared siblings, so they could remove biases that normally plague this kind of study.
They used differences in birth weight and breastfeeding duration between siblings to predict differences in adult CRP.
Their analysis showed that:
- Lower birth weights and shorter duration of breastfeeding predicted higher CRP levels in young adults
- For each extra pound of birth weight, the CRP level in young adulthood was 5% lower
- CRP levels were 20-30% lower in young adults who were breastfed for 3-12 months as babies compared to those who were never breastfed.
There were also dramatic racial, ethnic and education disparities. Babies born to white, Hispanic and more educated mothers were more likely to have higher birth weight and be breastfed, note the authors.
Study shows importance of breastfeeding for public health
Breast milk gives newborns essential nutrients and supports their immune system following birth.
The researchers conclude the results highlight the importance of promoting better birth outcomes and encouraging mothers to breastfeed for longer as a way to improve the general health of the adult population.
They add that increasing such awareness could narrow the intractable social gaps in adult health outcomes that are tied to inflammation.
Lead author Thomas McDade, professor of anthropology in Northwestern's Weinberg College of Arts and Sciences and faculty fellow of the university's Institute for Policy Research, says:
"The findings about breastfeeding and birth weight are particularly illuminating. The rates for many adult diseases completely mirror rates of low birth weight and low breastfeeding uptake and duration."
Breast milk gives newborns essential nutrients and supports their immune system following birth. It also affects the development of the immune system and metabolic processes linked to obesity - two ways that link to CRP production in adulthood.
Dr. Alan Guttmacher, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, says the study "helps us understand and appreciate the importance of breastfeeding, especially for low-weight infants," and suggests "that breastfeeding may reduce a major risk factor for heart disease, well into adulthood."
In 2013, Centers for Disease Control and Prevention reported that breastfeeding is on the rise among American mothers, with big increases in numbers still breastfeeding at 6 months.
The American Academy of Pediatrics guidelines recommend that babies have only breast milk for the first 6 months of their lives, and continue to be breastfed as other foods are added to their diet for at least 6 more months.