THURSDAY, Nov. 7, 2002 (HealthDayNews) -- Can the excesses of grandfathers be visited on their grandchildren?
People from Sweden whose paternal grandfather enjoyed a surplus of food during a particular period of their childhood had higher death rates from diabetes, according to new research appearing in the November issue of the European Journal of Human Genetics.
The implication is that a surplus of food leads to overeating, which, in turn, may lead to changes in the genes carried by sperm. The altered genes are then passed from generation to generation.
Earlier research has shown that food scarcity during a grandfather's "slow growth period," which occurs before puberty, led to longer lives for the grandchildren. An abundance of food had the opposite effect: shorter life spans.
For the study, the researchers used relatively low-tech methods to reach their startling conclusions. Survival statistics for groups of people born in 1890, 1905 and 1920 in an isolated community in northern Sweden were correlated with historical information on annual harvests and food prices, among other things.
The grandchildren of men who had had plentiful food supplies during the slow-growth period of their childhood were four times more likely to die of diabetes, says Dr. Gunnar Kaati, lead author of the study and an associate professor of social medicine at Umeä University in Umeä, Sweden. When the paternal grandfather lived through a famine during this same pre-pubescent period, the grandchildren were less likely to die of diabetes, a disease often caused by being overweight.
Additionally, when the father and the paternal grandmother were exposed to famine, children and grandchildren had reduced death rates from cardiovascular disease. And if a mother experienced an excess of food, her children's death rates from cardiovascular disease, but not diabetes, decreased, the study says.
How does this work?
There are a number of possible explanations, including genetic selection, but the one put forward in the new study suggests that some kind of "imprint mechanism" on the genes is involved.
"Nutrition affects ovaries and testes from the moment they form during fetal life through maturity," Dr. Marcus Pembrey, of University College London, writes in a commentary accompanying the study. "These are, potentially, very important findings hinting at some as yet undiscovered, transgenerational mechanism that 'captures' nutritional information from the previous generation(s)."
Dr. Steven Heymsfield is deputy director of the New York Obesity Research Center at St. Luke's-Roosevelt Hospital in New York City. He says the new study "does seem very interesting, that through some kind of imprinting the metabolic memory of what happened before is preserved."
Heymsfield adds that in light of other, related, theories, this one does not seem so farfetched. Other experts have postulated that dietary protein change while the fetus is in the uterus has delayed effects on the child's pancreas and insulin secretion, both of which play key roles in weight and the development of diabetes.
"Intrauterine changes predestine the child to metabolic illnesses," Heymsfield says. "People no longer think this is ludicrous."
The problem with the new study is in the proof. Proving this theory is likely to be very difficult, as there are so many variables to consider.
However, there could be important implications for prevention of diabetes.
"We cannot give the current children and parents or public health officials any serious advice out of the study," Kaati says. "Further insight might make this possible in the not too far future."
What To Do
For more information on the genetics of diabetes, visit the American Diabetes Association. For more on diabetes, check with the U.S. National Library of Medicine.
