Women in their late 30s and 40s who are trying to become pregnant are likely well-schooled in the fertility difficulties that often come with age. But could the secret to overcoming these hurdles be as simple as cutting back on calories? That's what a team of researchers from Massachusetts General Hospital in Boston think, after a study they conducted showed that older female mice fed calorie restricted diets had higher fertility rates and better egg quality than older mice fed without restrictions.
Though researchers can only speculate right now how calorie restriction works to boost fertility, they think their findings offer a new understanding of just how much metabolism can impact genetics. In the study, restricting calories prevented a spectrum of genetic abnormalities, such as extra or missing copies of chromosomes, which arise more frequently in egg cells of aging female mammals. Problems with aging eggs are a leading cause of infertility among older women.
"We found that we could completely prevent, in a mouse model, essentially every aspect of the declining egg quality typical of older females," says Dr. Jonathan Tilly, director of the Vincent Center for Reproductive Biology in the MGH Vincent Department of Obstetrics and Gynecology, who led the study.
But what about not-so-mousy women? "If we find a way to safely reproduce in humans the effects we see in this study—and even though this is a mouse study, we know these age-related egg cell defects are also seen in humans—we may be able both to improve a woman's chance of getting pregnant and, for those who do need assisted reproductive technology, to improve the quality of the eggs we use to minimize if not eliminate the age-related increase in Down syndrome and other chromosomal disorders," Tilly adds.
Before you start cutting back, consult with your doctor to make sure calorie restriction is something that might help, and not hurt, your chances of becoming pregnant. Calorie restriction is generally not for young women, adults with already low body fat percentages, or those with eating disorders.
But for the rest us? Other studies have shown that eating a healthy, nourishing "restricted food intake" diet may help us live longer and show fewer signs of aging than those who eat as much food as they want. Researchers point out the people of Okinawa, Japan, as naturally following a restricted calorie diet and being among the healthiest, long-lived humans on earth. The long-term effects of a caloric restriction diet in women and men are still being investigated, but some health improvements, including reductions in cholesterol levels and other cardiovascular risk factors, have already been reported.