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:
- a control group fed a healthy diet during both pregnancy and lactation
- a group fed a protein-restricted diet during both pregnancy and lactation
- a group fed a restricted diet during pregnancy but a healthy diet during lactation
- a group fed a healthy diet during pregnancy but a restricted diet during lactation
"Further studies are needed to determine the precise mechanisms at play and health outcomes later in the lifespan of the grandchildren. Diabetes and obesity are age-related conditions," Dr. Nathanielsz said.
The global incidence of type 2 diabetes is projected to double to 300 million by 2025 (information from Science, Jan. 21, 2005, page 369). Diabetes is a major health problem throughout the United States, including locally in Texas, and in Mexico. The disease is responsible for early death, painful and debilitating complications such as limb amputation and blindness, and vast national expenditures imposed upon the national economy.
Dr. Nathanielsz, who joined the Health Science Center in 2004 from New York University Medical School, is the author of several books, including "Life in the Womb: the Origin of Health and Disease" (Promethean Press, 1999) and "The Prenatal Prescription" (HarperCollins Publishers, 2001). He is a widely quoted authority on fetal and early development.
He said the finding that the diets of grandmothers can affect the health of grandchildren is "the confluence of nature and nurture – it’s one of the hottest health care stories there is."