In a new study, women were more likely to get breast cancer if they had regularly eaten french fries decades earlier as preschoolers.
The report appears in the online edition of the International Journal of Cancer. It's based on the Nurses' Health Study, a long-term health study of a large group of nurses.
The study focused on 582 nurses who had breast cancer and more than 1,500 who didn't have breast cancer in 1993. Their mothers were asked how often the nurses had eaten 30 different foods as preschoolers.
French Fries Stood Out
—French fries were the only food associated with higher risk of breast cancer.
—Foods that were not linked to an increase in breast cancer include cheese, butter, eggs, ground beef, and cookies.
—Whole milk was linked to a slightly lower risk of breast cancer, the study shows.
For every extra weekly serving of french fries that the women reportedly ate as preschoolers, their risk of breast cancer as adults rose 27 percent, write Karin Michels, ScD, PhD, and colleagues.
Michels is an associate professor of epidemiology at Harvard Medical School and Boston's Brigham and Women's Hospital.
View Results With Caution
Keep in mind:
—French fries weren't tested for any cancer-causing properties.
—People's memories of long-ago diets aren't perfect.
—The moms were in their 60s, 70s, and 80s when they were interviewed about what their kids ate decades earlier.
—The moms knew if their daughters had had breast cancer, which could skew their views of foods.
"We have to interpret this very cautiously," Michels tells WebMD. "We really would very much like other studies to confirm our findings before we go out to make public health recommendations."
Researcher's Note to Parents
Michels tells WebMD her study and work by other researchers "points towards a role for early life diet for various chronic diseases, including obesity, heart disease, diabetes, hypertension, and now we're adding cancer — in particular, breast cancer — to that list."
"I think this is just one more item that adds to the concern that parents should have about their child's diet," she continues. "We already have a lot of concerns about children's diets, given the obesity epidemic among children and the other chronic health outcomes."
"Parents have a particularly important role to ensure that their children have a healthy diet," says Michels. "There are plenty of reasons to watch children's diets so that they grow into healthy adults and we are not raising a generation of children that then have a variety of chronic diseases, three, four, or five decades down the line."
Fats at Work?
Michels says she doesn't know why french fries stood out. Saturated fats or trans fatty acids used to make french fries could play a role, but that's not certain.
The study spanned 40 years. During that time, preparation of french fries changed. Older women may have eaten fries baked at home in lard (rich in saturated fats). Others may have eaten fast-food fries cooked in oils high in trans fatty acids, says Michels.
She also encourages people to be "a little bit cautious" about the whole-milk findings, since today's milk has "a much higher content of hormones" than what the nurses drank as kids.
Long Time Frame
Why did Michels look at diet early in life and breast cancer?
"A girl's breast prior to puberty is much more susceptible to environmental and potentially cancer-causing influence than a breast of an adult woman," Michels says.
Michels says the study is one of the first, if not the first, of its kind to look at adult breast cancer risk and preschool diets.
"For some people, that might be so far removed from the time that you get the cancer. On the other hand, we also know that cancer takes decades to develop so it is less far-fetched than it might seem," says Michels.
It's "very hard" to put the increased risk into individual terms, since every woman has a different risk profile for breast cancer, says Michels.
SOURCES: Michels, K. International Journal of Cancer, online edition. Karin Michels, ScD, PhD, associate professor of epidemiology, Harvard Medical School, Brigham and Women's Hospital. News release, Brigham and Women's Hospital.