Researchers from the University of California at Davis found that a diet linked to obesity and harmful metabolic changes stimulated early breast growth and led to abnormal tissues in the breast that may produce breast cancer.

Scientists fed newly weaned mice a diet containing a fatty acid called 10,12 CLA which can trigger metabolic syndrome, a condition linked to obesity, diabetes and heart disease, the Daily Mail reported.

The fatty acid is present in hydrogenated fats, widely used in the manufacture of biscuits, cakes and processed foods.

Giving female mice the 10,12 CLA stimulated growth of their mammary ducts. This was despite the young animals lacking the hormone oestrogen, believed to be vital to female reproductive development.

In some animals, the altered diet also resulted in the kind of abnormal cell growth that can lead to breast cancer.

“These results lend support to increasing evidence suggesting a relationship between breast cancer risk and early life events that clearly include dietary components and their effects on aspects of metabolic dysregulation,” researchers were quoted as saying by the paper.

The cancer link could be due to excess levels of insulin, the scientists believe, pointing out that postmenopausal women with raised insulin levels had an increased risk of breast cancer.

“The findings of this study are particularly important when we superimpose them on data showing that girls are experiencing breast development at earlier ages, coincident with a growing epidemic of childhood obesity,” lead researcher Dr Russ Hovey, said.

The study was published in the journal Proceedings of the National Academy of Sciences.