Researchers have found evidence that a young girl's diet could affect her risk of developing breast cancer later in life.

The evidence linking a woman's breast cancer risk to her diet as a youth comes from mouse studies at the University of California Davis. Lead researcher Russ Hovey says investigators worked with female rodents whose estrogen production had been blocked. The female reproductive hormone is responsible for the development of sexual characteristics, including breast growth. Circulating estrogen from the ovaries has also been implicated in breast tumors. But the hormone's influence was eliminated in the subject mice.

The mice were then fed a calorie-rich diet containing a fatty acid known as 10, 12 CLA. It led to a pre-diabetic state called metabolic syndrome, marked by rising blood sugar levels, weight gain, elevated cholesterol levels and high blood pressure.

The fatty diet also stimulated breast growth in some mice, even though they lacked estrogen, according to Hovey. “What we’ve shown is that when we fed a diet that was supplemented with this particular type of fat, it then led to metabolic changes. But the thing that surprised us most was in fact that the breasts developed in these mice even though they had no ovaries and even though we used other methods to remove estrogen from their system,” he said.

The researchers found that the diet-induced breast growth also resulted in the development of tumors in some of the mice.

Hovey says not all of the mice fed the fatty diet developed tumors - suggesting that there may also be a genetic component contributing to breast cancer.

The take-home message, according to Hovey, is that the diets of young girls should be monitored to reduce the kinds of fats that can trigger cancer and other diseases.

“Like obesity for example, [or] Type 2 diabetes, [and] that might also be able to substitute or stimulate breast development, independent of estrogen,” explained Hover.

As Type 2 diabetes becomes more common around the world, the study’s findings suggest an epidemic of breast cancer might not be far behind.

An article on diet and breast tumor development is published in the journal Proceedings of the National Academy of Sciences.