For each additional serving of french fries per week when they were preschoolers, women had a 27 percent increased risk of breast cancer later in life.

"Researchers are finding more evidence that diet early in life could play a role in the development of diseases in women later in life," says lead author Karin B. Michels, ScD, PhD, a clinical epidemiologist at Brigham and Women’s Hospital (BWH) and associate professor at Harvard Medical School.

"This study provides additional evidence that breast cancer may originate during the early phases of a woman’s life and that eating habits during that phase may be particularly important to reduce future risk of breast cancer," she added.

Saturated Fats, Trans-Fatty Acids

Researchers analyzed the data of 582 women who had breast cancer in 1993 along with 1,569 women who then were free of the disease, to explore a possible relationship to preschool-age diet. All of the women were participants in the Nurses’ Health Study (NHS) and the Nurses’ Health Study II.

The researchers obtained dietary information from the women's mothers, who completed a food frequency questionnaire about their daughters' eating habits from three to five years of age. The mothers indicated how often their daughters ate or drank an average serving of 30 food items.

For each additional serving of french fries per week when they were preschoolers, women had a 27 percent increased risk of breast cancer later in life, Michels and her colleagues found.

While consumption of potatoes was not associated with adult breast-cancer risk, the researchers note, the preparation of french fries -- which typically involves frying oil high in saturated fats and trans-fatty acids -- might be relevant.

Role of Diet During Early Years

The study also found that daily consumption of whole milk was associated with a modest decrease in risk of breast cancer.

"These data have to be interpreted cautiously since the observed association between consumption of french fries and breast cancer is dependent on the validity of the maternal recall of the diet," Michels cautions.

"Mothers were asked to recall their daughter’s preschool diet after the participants' breast-cancer status was known, and it is possible that mothers of women with breast cancer recalled their daughter's diet differently than mothers of healthy women. Other foods perceived as less healthy, such as hot dogs or ice cream, however, were not associated with breast-cancer risk," she points out.

"Few data are available on the role of diet during early life for breast-cancer risk," says Michels. "Breast cancer is a devastating disease, and research such as this is important in helping guide future studies that will demonstrate how women can reduce their risk of this deadly disease."