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Girls who ate the most fruits and vegetables rich in carotenoids were less likely to get benign breast disease, a new study suggests.
Carotenoids are a group of pigments that typically produce an orange, red or dark green colour. They are believed to have antioxidant properties that may guard against disease.
Benign breast disease describes a variety of noncancerous conditions of the breast; some forms raise the risk of breast cancer.
Read: Cruciferous vegetables boost breast cancer survival
"There have been a number of studies about carotenoids and breast cancer," said lead researcher Caroline Boeke, a postdoctoral fellow at Channing Division of Network Medicine at Brigham and Women's Hospital and Harvard School of Public Health, in Boston.
Protective effect
While the studies have produced mixed results, she said, overall they suggest a protective effect of the carotenoids. So her team decided to analyse the intake of these vegetables by girls enrolled in an ongoing study that began in 1996.
For her study, Boeke and her colleagues looked at food reports from 1996 through 1998 and then evaluated reports in 2005, 2007 and 2010 from girls who got a diagnosis of benign breast disease from a doctor after having a biopsy.
In all, Boeke studied nearly 6 600 girls, and 122 reported a diagnosis of benign breast disease.
When she looked at carotenoid intake, she found high intakes were protective. "The odds of benign breast disease in those who consumed the most beta carotene were about half that of those who consumed the least," she said.
Girls in the highest intake group ate two to three servings of carotenoid-rich foods weekly, she said.
The study was published in Paediatrics.
"It's an observational study, so we can't say for sure the carotenoids cause the lower risk," Boeke noted. "We can only say there's an association."
Contributing factors
She did take into account other factors that might affect the risk of benign breast disease, such as alcohol intake, physical activity, family history and body mass index (a measure of body fat using height and weight).
Why might the fruits and vegetables help? It's not known for sure, but Boeke said it may be due partly to their antioxidant properties. Carotenoids absorb harmful substances known as free radicals which can harm cells.
The study looked only at food intake, not supplements, and Boeke said she would not recommend supplements since other research has found some harmful effects with supplement use.
Other foods that are rich in carotenoids include yams, melons, spinach and kale.
The most common kind of benign breast disease in teens and young women is a noncancerous tumour known as a fibroadenoma, according to Boeke.
The period of time between the start of a girl's period and the first birth is a sensitive one for the breasts, as they are very vulnerable to environmental exposures, according to background information in the study.
Subject to error
Not many lifestyle habits have been shown to protect against benign breast disease, said Dr Joanne Mortimer, director of women's cancer programs and co-director of the breast cancer program at the City of Hope Comprehensive Cancer Centre, in Duarte, California.
The study has limitations, she said, including the self-report by the girls of a benign breast disease diagnosis by a doctor and the food questionnaires, which are always subject to error since it's difficult to remember exactly what was eaten.
Read more:
Breast cancer: the latest research
The genetics of breast cancer
Breast cancer and the younger woman
