By Salynn Boyles
WebMD Health News
Reviewed by Louise Chang, MD
Dec. 6, 2012 -- Women now have one more reason to eat their fruits and veggies.
A new study suggests that women with higher levels of carotenoids (nutrients found in fruits and vegetables) have a lower risk of breast cancer -- especially cancers that are harder to treat and have a poorer prognosis.
When researchers from Harvard Medical School pooled the results of studies that measured carotenoid levels in women's blood, they found that those with the highest levels had a lower risk of breastcancer compared to those with the lowest levels.
The association appeared to be stronger for smokers than for non-smokers and for women who were lean compared to those who were overweight.
Eat Your Carrots, Avoid Breast Cancer?
Carotenoids are the micronutrients in fruits and vegetables that give them their vibrant orange, yellow, and red colors. Foods that are good sources of carotenoids include carrots, sweet potatoes, spinach, kale, red peppers, and winter squash.
Having higher circulating blood-carotenoid levels may be particularly protective against breast cancers that do not need estrogen to grow.
The finding suggests that eating a healthy, plant-based diet may be one of the first modifiable risk factors for these less common, poorer-prognosis cancers.
"Breast cancer risk factors we have known about all involve more common estrogen-dependent cancers," says researcher A. Heather Eliassen, ScD.
The study combined data from eight trials that included more than 3,000 women with breast cancer and close to 4,000 women without the disease.
It is not clear if carotenoids directly lowered cancer risk.
But Stephanie Bernik, MD, who is chief of surgical oncology at Lenox Hill Hospital in New York City, says the message to women does not change.
"We have said if we want to reduce the risk of cancer -- not just breast cancer -- eating a plant-based diet low in fat and animal protein may help," she says. "This study, like others, suggests this is the case."
The study was published Dec. 6 in the Journal of the National Cancer Institute.
Fruits, Veggies May Help High-Risk Women Most
Bernik says the suggestion that eating plenty of fruits and vegetables may be particularly beneficial for women at risk for non-estrogen-dependent tumors is especially intriguing.
Many breast cancers in women with a family history of the disease and specific genetic mutations that dramatically increase their breast cancer risk fall into this category.
Sue Friedman, DVM, says making healthy lifestyle choices is important for women with a genetically increased risk for cancer. She is executive director of the genetic cancer research and support group Facing Our Risk of Cancer Empowered (FORCE).
But she adds that maintaining a healthy lifestyle is no guarantee that a high-risk woman will not get cancer, and it's no substitute for aggressive screening.
Friedman should know.
She exercised regularly, didn't drink or smoke, and had been a vegetarian for 15 years when she was diagnosed with breast cancer at age 33.
At the time she was unaware that she carried the BRCA2 mutation, which dramatically increased her breast cancer risk.
Now more than 14 years later, Friedman believes her healthy lifestyle is one of many things that has contributed to her survival.
"It's exciting that fruits and vegetables may help prevent breast cancer, but we don't want to give high-risk women a false sense that if they eat right they don't have to be vigilant about screening," she says.
SOURCES: Eliassen, A.H., JNCI, Dec. 6, 2012. Heather Eliassen, ScD, Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School. Stephanie Bernik, MD, chief of surgical oncology, Lenox Hill Hospital, New York, N.Y.Sue Friedman, DVM, executive director, Facing Our Risk of Cancer Empowered. News release, JNCI. WebMD: "Types of Breast Cancer."
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