Weight gain halted by vitamins, study of mice finds

But the mice didn't get any plumper when that diet was supplemented with folic acid, vitamin B-12, choline and betaine, according to a study published Tuesday in the International Journal of Obesity.

Because the genetic makeup of the mice was the same, the scientists concluded that the diet supplements had managed to suppress the activity of key genes related to obesity.

Dr. Robert Waterland, an assistant professor of pediatrics in the Children's Nutrition Research Center at Baylor College of Medicine in Houston and lead author of the study, said that the supplements are known to promote methylation, a process of chemically tagging DNA that suppresses genes.

Such influences, termed epigenetic because they stem from factors outside of the genome, play a major role in development.

"The entire genome is in nearly all of our cells and yet our liver cells express a very different set of genes than the cells in our gut," Waterland said.

Epigenetic effects are known to contribute to cancer, but their influence on weight regulation is an open question.

"Everybody knows that what pregnant women eat matters for their children," said Craig Warden, a professor of pediatrics and genetics at UC Davis who was not involved in the study.

"This could be part of that story."

Waterland said that methylation may affect development of the hypothalamus, a region of the brain that controls appetite, and he plans to research this in both mice and humans.

Although people lack the gene that originally made the mice obese, the study "makes a nice parallel with humans because we know that a lot of humans have a genetic predisposition to obesity, especially in the current environment of food excess," Waterland said.

wendy.hansen@latimes.com