March 12, 2004 -- Can a nutrient found abundantly in eggs help pregnant women give birth to brainier babies? Animal studies show it can, and now new research may help explain why.
Duke University investigators report that brain cells in regions that are associated with memory were larger and functioned more efficiently in rats exposed to high amounts of the nutrient choline in the womb than in the offspring of mothers fed normal diets.
Earlier animal studies have linked prenatal exposure to higher than normal amounts of choline in the womb and improved learning and memory. Human studies are just beginning, but the hope is that the same memory-boosting effects will be seen in the offspring of pregnant women who eat choline-rich diets.
"The potential implications are huge," Duke researcher Scott Swartzwelder, PhD, tells WebMD. "It is possible that simple changes in a woman's diet during pregnancy could mean lifelong benefits for her unborn child."
In addition to egg yolks, choline is found in milk, nuts, fish, certain vegetables, liver and other organ meats, as well as in human breast milk. It is available in many foods yet the normal sources provide insufficient amounts during times of heightened needs, such as pregnancy or during breast feeding.
In the Duke study, Swartzwelder and colleagues explored the effects of choline exposure in the womb on the cells in the region of the brain associated with learning and memory, known as the hippocampus. They fed one group of pregnant rats extra choline and another group the same diet with normal amounts of the nutrient, and later looked for differences in the cells that conduct nerve impulses, known as neurons.
The researchers found that the neurons of the choline-exposed rats were larger than the control rats, and they possessed more tentacle-like "dendrites" that receive signals from other neurons. The neurons also fired electrical signals more strongly and rebounded more quickly between firings. The findings are published in the April issue of the Journal of Neurophysiology.
"Collectively, these behaviors should heighten the neurons' capacity to accept, transmit and integrate incoming information," Swartzwelder says.
Steven H. Zeisel, MD, who chairs the nutrition department at the University of North Carolina, Chapel Hill, has been studying choline in animals for more than a decade and is also four years into a study examining the effects of choline deficiency in humans. He says those studies show that the current recommended intake of half a gram a day -- the amount gotten by eating two large eggs -- is probably not enough for some groups, especially young men.
Soon to be published animal studies show that choline influences cell division by promoting a biological process which helps make proteins. According to Zeisel, choline acts as a switch to turn this process on and off.
"Our hypothesis is that the effects we have seen in animals are due to [choline-induced] changes in this [methyl] switch that turn on and off gene expression," he tells WebMD.
Zeisel is also beginning a pilot study assessing choline supplementation in pregnant women. The women will get the equivalent of twice as much choline as is in a normal diet by eating three eggs a day or taking a supplement from their 15th week of pregnancy until a month after giving birth. Infant-oriented memory tests will then be performed on their babies when they are 10 months old and 1 years old.
"This is a small study right now, but if the effect is large it won't take long to see it," he tells WebMD.
He says there is probably no downside to eating as many as three eggs a day if you are pregnant, but adds that it is probably more important to eat a healthy, balanced diet than to eat a lot of any one food.
"Pregnancy is no time to be experimenting with your diet," he says. "We may identify a benefit from boosting choline, either with food sources or supplements. But at this point I would be cautious."