Can broccoli and its botanical cousins increase the chances of surviving breast cancer?
The results of a joint U.S.-Chinese study found that breast cancer patients who ate more broccoli or other cruciferous vegetables enjoyed improved survival rates.
Broccoli belongs to a family whose members are called cruciferous vegetables.
The botanical name of this plant family – Cruciferae (AKA Brassicaceae) – comes from the cross-like marking on the flower-buds of some species.
Members include cabbage, kale, chard, collards, kohlrabi, Brussels sprouts, turnip, rutabaga, bok choy, cauliflower, mustard greens, and wasabi.
Cruciferous vegetables are rich in sulfur compounds called glucosinolates, which enzymes convert into compounds – isothiocyanates (ITCs) and indoles – that display anti-cancer effects.
As the authors of the new study wrote, “These bioactive compounds have many anti-cancer properties that may influence cancer development, progression and survival. For example, ITCs and indole-3-carbinol have been shown to reduce tumor proliferation in human breast cancer cells” (Nechuta SJ et al 2012).
Population study reinforces crucifers' anti-cancer reputation
The study looked at women in China, and was presented by Sarah Nechuta, Ph.D., MPH, at the American Association for Cancer Research Annual Meeting in Chicago (Nechuta SJ et al 2012).
Nechuta and her colleagues compared the reported intake of cruciferous vegetables among breast cancer patients.
The women were participating in the Shanghai Breast Cancer Survival Study … a prospective study of 4,886 Chinese women aged 20-75 who were diagnosed with breast cancer (stage 1 to stage 4) from 2002 to 2006.
The international team's analysis linked higher cruciferous vegetable intake during the first 36 months after breast cancer diagnosis to a reduced risk for death from any cause, breast cancer-specific death, and disease recurrence.
Women's survival rates varied in a persuasive “dose–response” pattern … as women consumed more cruciferous vegetables, their risk of death or cancer recurrence decreased.
By about five years after diagnosis, the women whose self-reported intake of cruciferous vegetables ranked in the top one-fifth – an average of 150 grams (five ounces) a day – were 42 percent less likely to have died from breast cancer.
(One cup of cooked broccoli, cauliflower, Brussels sprouts, mustard greens, cabbage, or kale provides about 150 grams.)
These women were also 58 percent less likely to die from any cause compared to women in the bottom fifth, who ate less than 54 grams a day.
Further, the women in the top fifth of cruciferous vegetable consumption were also 19 percent less likely to see their breast cancer return.
Dr. Nechuta noted that cruciferous vegetable consumption habits differ between China and the United States, and suggested this fact be considered when generalizing these results to U.S. breast cancer survivors.
“Commonly consumed cruciferous vegetables in China include turnips, Chinese cabbage/bok choy and greens, while broccoli and Brussels sprouts are the more commonly consumed cruciferous vegetables in the United States and other Western countries,” she said. “The amount of intake among Chinese women is also much higher than that of U.S. women” (VICC 2012).
Dr. Nechuta called for studies to measure the levels of active compounds in cruciferous vegetables, and characteristics in women that may influence their effects.
In the meantime, as Dr. Nechuta said, “Breast cancer survivors can follow the general nutritional guidelines of eating vegetables daily and may consider increasing intake of cruciferous vegetables, such as greens, cabbage, cauliflower and broccoli, as part of a healthy diet” (VICC 2012).
Dong JY, He K, Wang P, Qin LQ. Dietary fiber intake and risk of breast cancer: a meta-analysis of prospective cohort studies. Am J Clin Nutr. 2011 Sep;94(3):900-5. Epub 2011 Jul 20.
Keck AS, Finley JW. Cruciferous vegetables: cancer protective mechanisms of glucosinolate hydrolysis products and selenium. Integr Cancer Ther. 2004 Mar;3(1):5-12.
Nechuta SJ et al. Cruciferous vegetable intake after diagnosis of breast cancer and survival: a report from the shanghai breast cancer survival study. Abstract Number LB-322, Poster Section 40. Tuesday, April 3, 2012. McCormick Place West (Hall F).
Vanderbilt-Ingram Cancer Center (VICC). Cruciferous Vegetables and Breast Cancer. April 6, 2012. Accessed at http://www.vicc.org/news/2012/04/breast-cancer-study-points-to-cruciferous-vegetables-benefit/
Zhang CX, Ho SC, Cheng SZ, Chen YM, Fu JH, Lin FY. Effect of dietary fiber intake on breast cancer risk according to estrogen and progesterone receptor status. Eur J Clin Nutr. 2011 Aug;65(8):929-36. doi: 10.1038/ejcn.2011.57. Epub 2011 May 4.