An innovative study published in the latest online edition of the Journal of Physiology provides the first evidence that the insulin resistance typical of type 2 diabetes can be "programmed" across two generations by poor nutrition during a grandmother’s pregnancy and lactation.
The study, from the University of Texas Health Science Center and the Institute of Medical Sciences and Nutrition in Mexico City, showed that grandsons and granddaughters of female rats fed an inadequate diet during pregnancy and/or lactation were more likely to become obese and insulin resistant than grandchildren of females fed an adequate diet.
The research dramatically extends previous findings that poor maternal nutrition during pregnancy and lactation predisposes the first generation of offspring to diabetes. The study is the first to show that the adverse effects can be passed to adult grandchildren across two generations.
"These new findings with our colleague Dr. Elena Zambrano and her team in Mexico stretch the unwanted consequences of poor nutrition across generations," said Peter W. Nathanielsz, M.D., Ph.D., professor and director of the new Center for Pregnancy and Newborn Research at the Health Science Center. "It offers us important clues about the origins of insulin resistance and type 2 diabetes. Knowledge of the origins of type 2 diabetes has the potential to improve the health of millions as well as deliver very significant economic savings.
"The granddaughters were more affected when their maternal grandmothers were undernourished during pregnancy," Dr. Nathanielsz said. "The grandsons, however, were more affected when their maternal grandmothers were undernourished during lactation. Thus, there are gender differences in the effects on the grandchildren, according to the time of exposure to a poor diet during their grandmothers’ own development."
Other researchers who have explored the issue have not tried to tease out the effects of poor nutrition in pregnancy in distinction to lactation.
Dr. Nathanielsz said the finding is important because it re-emphasizes the need to provide better maternal care and advice to women about good nutrition both during pregnancy and lactation.
Rats live three years on the average. Thus far, the researchers have followed the grandsons and granddaughters for one year and continue to analyze data on obesity and insulin resistance.
Each of the grandmothers was assigned to one of four study groups: