Last month we looked at some of the extraordinary benefits of breast feeding.
There is an interesting paper in this month's issue of the journal Pediatrics.
Approximately 19 percent of children are prone to the chronic and recurrent ear infections collectively known as otitis media. These infections can cause deafness and thereefore interfere with the development of language and lead to learning difficulties. We have known for many years that there can be a genetic predisposition to otitis media, but there has been little research to try and pinpoint the specific genes involved. There is also a complex relationship between genes, specific infectious agents and environmental factors such as exposure to cigarette smoke and breast-feeding.
The new research from the University of Texas Medical Branch at Galveston examined genetic samples taken from 505 children in Texas and Kentucky, about 60 percent of whom were classified as "otitis media susceptible" because they had:
- Suffered an ear infection before the age of 6 months
- Or undergone three or more episodes of acute otitis media within a six-month period
- Or four or more episodes within a 12-month period
- Or had six or more episodes by age 6.
- Or had required drainage tubes to reduce recurrent or persistent ear infections
The researchers looked for small genetic variations called "single-nucleotide polymorphisms," - or SNPs - in three important genes that produce inflammatory signaling molecules for the immune system.
Two genes known known to generate the immune proteins known as tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6). SNPs in each individual gene were enough to create an increased risk for childhood ear infections, and simultaneous SNPs in both genes increased the risk even further. These particular genetic variations cause a greater production of inflammatory signaling molecules and reduce the effectiveness of the immune system.
But here is the fascinating thing: the researchers found that the genetic effect could be counteracted by breast-feeding, which is well known to increase immune resistance.
We have here another fine example of how a healthy practice can overcome a genetic predisposition to illness. Remember what I have said many times before: Biology is not destiny.
On the hand another environmental factor - exposure to cigarette smoke - increased vulnerability to otitis media in children with the TNF-alpha gene variation. Cigarette smoke exposure alone was not enough to increase the risk for ear infections.