You now have yet another reason to eat lots of fruits and vegetables. Scientists have found that women with high levels of different carotenoids in their blood have a 15 to 20 percent lower risk of breast cancer than those with lower levels.
Carotenoids are pigments that give plants their vibrant colors. “Carotenoids act as antioxidants and soak up excess Free Radicals that are normally generated as part of metabolism,” A. Heather Eliassen, corresponding author of the study, tells TheDoctor.
Primary sources of carotenoids in the U.S. diet include carrots, which are rich in alpha-carotene; sweet potatoes and leafy greens, which are rich in beta-carotene; and tomatoes, which are rich in lycopene.
If too many antioxidants build up in the blood, it could result in what is called a state of oxidative stress she explained. Prolonged Oxidative Stress may lead to diseases such as cancer. “So having more available antioxidants could be important,” says Eliassen, an assistant professor of medicine at Harvard Medical School and an assistant professor of epidemiology at the Harvard School of Public Health.
One interesting finding was that that the association between carotenoid levels in the blood and breast cancer risk is particularly strong for tumors that are estrogen receptor negative (ER-). This finding supports previous evidence of this association, says Eliassen. She also says that this association is of particular interest because ER- breast tumors are more aggressive and harder to treat, and researchers know less about them and how to prevent them.
The investigators also found that the protective effect of carotenoids was greater among women who smoke versus those who do not smoke. Smoking increases oxidative stress so, “We expected that women who had higher levels of exposure to potential oxidative stress might benefit more from having higher levels of antioxidants in their diet,” Eliassen says.
An unexpected finding, however, was that carotenoids were more beneficial to women with a lower body mass index (BMI), versus those with higher BMI. “The association with body weight was not what we expected, because we would have expected obesity or being overweight to be a source of oxidative stress,” says Eliassen.
More research is needed to determine exactly what is going on, but that won't change the takeaway message for the rest of us. As Eliassen puts it, “Recommending an increase in consumption of fruits and vegetables is healthy for many reasons, and I do not think you should hold back on adding them to your diet based on these findings.”