Frequent bouts of diarrhea can be bad news for babies, even decades later: A new study has found a correlation between childhood infections and significant shortening of telomeres, a phenomenon that’s linked to the cellular aging process.
The findings, published today in the American Journal of Human Biology, point to a potential linkage between the environmental and genetic factors that play a role in human health.
They also point to the importance of initiatives aimed at curbing infant diarrhea, such as those funded by the Bill & Melinda Gates Foundation.
Researchers led by University of Washington anthropologist Dan Eisenberg found the correlation by sifting through the Cebu Longitudinal Health and Nutrition Survey, a database that tracked the health of more than 3,000 infants born in the Philippines in 1983 and 1984.
The babies’ mothers provided details about their children’s health and feeding habits every two months, from birth through the age of 2. The data included statistics showing how often the mothers breastfed their babies, and how often the babies suffered from diarrhea, a sign of infection.
Follow-up health surveys were conducted for 20 years. In 2005, when the kids were in their 20s, 1,776 of them donated blood samples for analysis.
Eisenberg analyzed the genetic makeup of cells from those samples, focusing on snippets of DNA known as telomeres.
Telomeres are protective “caps” that sit at the ends of each of the chromosomes in a cell, like the protective plastic ends on shoelaces. As people age, and their cells divide over and over again, those telomeres become shorter, reducing their protective benefit. Scientists have found that shorter telomeres are associated with cancer and age-related diseases.
The analysis of the Philippine health database showed that babies who suffered the most cases of diarrhea at the age of 6 to 12 months had the shortest telomeres at the age of 21 or 22. Babies who had the average number of diarrheal infections showed the equivalent of three extra years of telomere aging as adults, compared with those who had no reported infections as babies.
“These are important and surprising findings because – generally speaking – shorter chromosome ‘caps’ are associated with a higher burden of disease later in life,” Eisenberg said in a news release.
One possible explanation for the correlation is that frequent infections force increased cell replication and inflammation, both of which can shorten telomeres.
Another explanation could be that the babies’ chromosomes had shorter telomeres at birth, and that somehow left them more vulnerable to childhood infections.
Eisenberg expected to find that the babies who were breastfed had longer telomeres as adults, because breastfeeding is thought to provide infants with beneficial antibodies and leave them less vulnerable to water-borne infections. But that didn’t turn out to be the case.
More research will be required to answer the questions raised by the study, Eisenberg said.
Regardless of the effect on telomeres, childhood diarrhea is a serious public health concern, particularly in developing countries. The World Health Organization says it’s the No. 2 cause of death for children younger than 5, killing 760,000 annually. (Pneumonia is considered No. 1.)
The Gates Foundation has provided tens of millions of dollars in grants aimed at reducing the global burden of diarrheal diseases and other gastrointestinal diseases, through measures ranging from better sanitation to the development of new vaccines to microbiome research.
Thanks in part to the foundation’s funding, Seattle-based PATH is making progress on a campaign to make anti-diarrheal treatments more widely available and create new drugs to fight the disease.