The most up-to-date research done on this found that children who are breastfed are more likely to recover from stuttering and return to fluent speech. The study of 47 children who began stuttering at an early age found that those who were breastfed longer were more likely to recover. 1
What the study looked at
The research 2 was undertaken by Nicoline Ambrose and Jamie Mahurin-Smith from the University of Illinois, in 2013, who studied data from the Stuttering Research Project. The 47 child stutterers entered the programme between ages 2 and 6. They were assessed every six months for two years, annually for two more years, and had a final follow-up five to eight years later. 17 children had persistent stuttering (also known as stammering) and 30 recovered naturally.
The researchers asked the mothers about their breastfeeding experiences and found no evidence of an underlying neurological problem that could have inhibited the children’s ability to breastfeed and to speak fluently later in life.
Boys seem to benefit most
Stuttering usually affects children ages 2 to 5. About 5 percent of children will stutter at some time in their lives, but most outgrow the speech deficit. It affects children from all backgrounds. Preschool boys are twice as likely to stutter as are girls, but boys become three or four times more likely to stutter as they grow older, according to the National Institutes of Health 3. The NIH says that stuttering rarely has psychogenic roots; meaning the cause is nearly always physiological rather than psychological.
Boys, who are disproportionately affected by stuttering, appeared to benefit the most from breastfeeding. The study found the boys who breastfed for more than a year had approximately one-sixth the odds of developing persistent stuttering than boys who never breastfed. The results were not statistically significant in girls who stuttered. “Girls and boys start stuttering with much more similar frequencies, but boys are a lot more likely to keep going than girls are, so it seemed likely we would see a stronger effect among boys” Mahurin-Smith said.
Link between breastfeeding and language development
Mahurin-Smith said “We’ve known for years that both genetic and environmental factors contributed to stuttering, but our understanding of the specific environmental variables has been less clear.” Several earlier studies had found “a consistent association between breastfeeding and improved language development” the researchers said.
A 1997 study 4 found that babies breastfed for more than nine months had a significantly lower risk of language impairment than those breastfed for shorter periods of time, which was backed up by a later study.5 Another study 6 found that infants who breastfed were more likely to produce “variegated babbling at earlier ages,” a key marker of healthy language development.
A recent study 8 by Brown University researchers found on magnetic resonance imaging scans that by age 2, babies who were breast-fed for at least three months showed increased brain development compared with those fed formula or breast milk plus formula. This study looked at the effects of myelination and problems with this have been implicated in stuttering as well. Myelination is the process by which a fatty layer, called myelin, accumulates around nerve cells (neurons) enabling them to transmit information faster and allowing for more complex brain processes. The process is vitally important to healthy central nervous system functioning.
The infant brain triples in size in its first year of life, and “more than half of the solid weight of that newly built tissue will be lipid,” the researchers wrote. DHA is the fatty acid most prevalent in the mammalian brain. Infants lacking adequate DHA in the diet can synthesize it from other fatty acids, but “research shows that the rate at which DHA is incorporated into brain tissue outstrips the rate at which it can be synthesized.”
Multiple studies suggest that the lack of adequate DHA in development can impair brain structure and function, Ambrose said. Fatty acids also are known to influence gene expression, she said, binding to transcription factors that can regulate the activity of many genes.
Components of breastmilk may hold the key
Ambrose and Mahurin-Smith suggest that essential fatty acids found in breastmilk but lacking in infant formulas* may help explain why longer duration of breastfeeding is associated with better brain and language development.
“Long-chain fatty acids found in human milk, specifically docosahexaenoic acid and arachidonic acid, play an important role in the development of neural tissue” Mahurin-Smith said. “Fluent speech requires an extraordinarily complex sequence of events to unfold rapidly, and our hypothesis was that early differences in neurodevelopment could cause difficulties with speech fluency later in life”.
Mahurin-Smith added “Everybody knows that children are building new brain tissues at a rapid rate during their first couple of years of life but what most people don’t think about is what kind of building blocks you need for making a brain.” Ambrose added “It may be that fatty acid intake affects the expression of genes responsible for stuttering.”
*The synthesisted DHA added to formulas is in a different biological environment to breastmilk, which is a species-specific, living substance. Formula contains no co-enzymes or co-factors to enable the fats to work optimally. 8
Findings could improve understanding of persistent stuttering
Mahurin-Smith said that the findings could improve understanding of stuttering persistence and recovery. She added, “Our study adds to the evidence suggesting that human milk can exert a significant influence on neurodevelopment.” However she cautioned that the results of the study were no “magic bullet,” as some boys continue to stutter despite being breastfed. She said it was important that mothers did not feel guilty over what they did or didn’t do in the early years as it was impossible to know if the outcome might have been different.
Dr. Esther Krych, a pediatrician at Mayo Clinic, said she found the results “really interesting” and commended the authors for uncovering another potential benefit to breastfeeding. “They highlight nicely that breastfeeding isn’t a cure-all, but at the same time that there may be benefits to breastfeeding we still have not discovered.”
More about the researchers
The study was published in the June 2013 online issue of the Journal of Communication Disorders and was carried out by Jamie Mahurin-Smith, while she was a doctoral student at the University of Illinois at Urbana-Champaign, and Nicoline Ambrose, Associate Professor Emeritus in the Department of Speech and Hearing Science, also at the U. of I. at Urbana-Champaign.
Mahurin-Smith, who is a mother of five, is now assistant professor in the Department of Communication Sciences and disorders at Illinois State University.
Jamie Mahurin-Smith was a La Leche League Leader from 1998-2008 and is now an IBCLC. She first got the idea for this study when she was living in Edinburgh and was reading Facts about Breastfeeding. She had to wait seven years to test her hypothesis but it all started in Scotland and Jamie says she has warm memories of the Edinburgh LLL group and her co-Leaders.
Written by Anna Burbidge for LLLGB, 2014