NEW YORK (Reuters Health) - young adults born by caesarean section are more likely to be obese that those delivered vaginally, suggesting that c-sections may be feeding the obesity epidemic, the researchers found.
But the theory is controversial. One expert warned that scientists are still far from pinning expansion jump on more elevated levels of C-sections.
In the new study, Brazilian researchers found that among more than 2 000 23 to 25 years, 15% of those delivered via profile c were obese compared to 10% of those who were born naturally.
The team reviewed a number of other factors that could potentially explain the connection, such as heavier weight at birth or income and education levels (more educated mothers had a higher rate of profile in C).
But, even after accounting for these factors, profile c remains linked to a 58% increase of the risk of obesity in adulthood, according to Dr. Helena Goldani and his colleagues.
The conclusions do not cause and effect, establish Goldani, Universidade Federal Rio Grande do Sul in Porto Alegre, told Reuters Health in an e-mail. And there would be other explanations. In conclusion, she said.
Yet, it is possible that C-sections may directly affect the risk of becoming obese later in life, to question the researchers.
This is because babies born via profile in c are not exposed to the beneficial bacteria in the birth canal and therefore they could take more time to accumulate the Bifidobacteria and other germs that could influence their metabolism.
Similarly, the obese adults tend to have less of these good bacteria in their gut than people of normal weight.
A researcher not involved in the study said that while the theory is "interesting", this study offers no evidence that C-sections are to blame.
"I think that all that they have shown is an association." "They have not established any mechanism or cause to effect," said Dr. Xavier Pi-Sunyer, Director of the Centre for research of New York obesity, St. Luke's Hospital.
A major weakness, he said to Reuters Health, is that the study had no information on the weight of mothers.
Obese women are more likely that thinner women need a profile in C. Similarly, they are more likely to have children overweight or are obese.
"It's a huge gap in the data," said Pi-Sunyer.
However, he noted that other researchers are looking on the question of why obese people tend to have a different composition of bacteria in the intestines than thinner people.
A theory is that the variation of bacterial intestinal …ou and contributes to obesity in causing people burn less calories and store more as fat.
If this is the case remains uncertain, however, and the role of C-sections is even less clear.
"It's an interesting conclusion," said Pi-Sunyer. "But it raises more questions he answers, and requires much more research."
He said that future studies will have take account of "parasites" factors, such as weight mothers and diabetes related to pregnancy, to show if the link between sections c and obesity is real.
Goldani agreed that other studies in other countries are necessary - including studies that measured the intestinal bacteria of newborn infants, and then follow them over time to plot the changes in their weight.
Brazil has long had one of the highest rates of profile in c in the world. 2,057 Adults in this study, which are born in the 1970s, 32% were born via profile c. It is estimated today that C-sections are performed in approximately 44% of Brazilians births, of which many are considered unnecessary.
Rate profile in c is also high in the United States, where it represents approximately 33% of births.
"An underlying message in this (report) seems to be that there are fewer C-sections done," said Pi-Sunyer.
That may well be, he added, but not because it will make everything to solve the problem of obesity.
SOURCE: http://bit.ly/laOPGb American Journal of Clinical Nutrition, online on April 20, 2011.
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