In mice with a type of heart disease found in humans, switching from a standard soy-based diet to one in which milk is the major protein source radically improves the disease and heart function, researchers report in the Journal of Clinical Investigation.

“These results were quite surprising to us and may, in the long-run have relevance to humans,” said senior investigator Dr. Leslie A. Leinwand.

However, she added, “I think it is important to keep in mind that the negative effects of the soy diet are only in males with this specific genetic heart disease,” known as dilated cardiomyopathy.

Leinwand of the University of Colorado Health Sciences Center, Denver and colleagues note that on a soy diet the male mice progress to heart failure.

However, when the animals were switched to a milk protein-based diet they no longer developed severe heart disease and the heart size and pumping ability were preserved.

“We are currently extending these studies to include the effects of the soy diet on other disease models and are conducting more extensive studies on normal healthy mice,” Dr. Leinwand continued.

“It is far too early to extend these observations to humans,” she cautioned. However, “diet has a much more profound effect on the heart than I think would have been anticipated - at least in mice - and may also be an important factor in human health and disease.”

SOURCE: Journal of Clinical Investigation, January 2006.