Fast food consumption is typically associated with health issues such as weight gain, high blood pressure and high blood sugar. Researchers now say processed foods and those that are high in sugar, protein and fat must be avoided by teens to prevent future breast cancer risk.

In a mice study, researchers from the Medical University of South Carolina (MUSC) evaluated how advanced glycation end products (AGEs) found in fast food were linked to pubertal breast changes, which manifest as increased breast density and risk of breast cancer in the future.

AGEs are harmful proteins or lipids that can increase the risk of developing diabetes, heart disease and insulin resistance. They are found in fast food cooked at very high temperatures that involve grilling, frying or toasting.

"Increased AGE levels are associated with increased breast cancer risk, however, their significance has been largely overlooked due to a lack of direct cause-and-effect relationship," researchers wrote.

The team evaluated the effect of AGE on mammary gland development during puberty. During the trial, the mice were divided into three groups: the control group was placed on a regular diet, while the other two groups received a low AGE diet and a high AGE diet respectively.

The team observed that mice fed with high AGE diets showed Atypical hyperplasia – a premalignant condition that can progress into breast cancer.

"Histological analysis revealed the high AGE diet delayed ductal elongation, increased primary branching, as well as increased terminal end bud number and size. The high AGE diet also led to increased recruitment and proliferation of stromal cells to abnormal structures that persisted into adulthood," the researchers said.

Increased stromal cells are associated with higher breast density, a factor that can raise the risk of breast cancer to eight times.

"Decades ago, I formulated a hypothesis that the seeds of future breast cancer are sown during puberty when the breast is undergoing development. Breast development during puberty produces a vulnerable window of several years of time. Any environmental insult, including excessive chest X-rays or the toxic products from fast-food cooking, can be amplified if it occurs during puberty. The understanding of this link between breast development and future breast cancer should be used to inform nutritional guidelines for adolescent girls," said physician-scientist Dr. Steven Quay, who was not involved in the latest study.

"Guidelines for school food programs should be developed to decrease AGE products in the lunch menu offerings, as well as an educational program for pediatricians and parents on the dangers of fast food during this vulnerable development window. These simple changes in lifestyle could have a significant impact on reducing the 250,000 breast cancers that are diagnosed each year in the United States," he added.