Cruciferous veggies protective against breast cancer?

An analysis using data from two large prospective studies demonstrates the protective effect of cruciferous vegetable consumption against breast cancer.

“Cruciferous vegetables are rich and unique sources of bioactive phytochemicals, particularly glucosinolates (GLSs),” said study investigator Dr Andrea Romanos-Nanclares from the Harvard Medical School and Brigham and Women’s Hospital, Boston, Massachusetts, US, during her presentation at SABCS 2025.

“The hydrolytic products of GLSs, mainly isothiocyanates and indoles, may have chemopreventive properties. They appear to inhibit multiple stages of cancer development by influencing cell proliferation, DNA repair, inflammation, angiogenesis, and oxidative stress, among others,” she continued. [Annu Rev Nutr 2025;45:171-195]

However, epidemiologic studies on the anticarcinogenic effects of cruciferous vegetables are limited, she pointed out. [Nutr Rev 2025;83:842-858; BMJ 2016;353:i2343; Int J Cancer 2019;144:1496-1510]

Romanos-Nanclares and her team evaluated the associations between cruciferous vegetable consumption (broccoli, cauliflower, cabbage/coleslaw, Brussels sprouts, kale, mustard greens, chard) and total and subgroup-specific GLSs with breast cancer risk in the NHS (n=121,700) and NHSII (n=116,429). The cumulative average of cruciferous vegetable and GLS intake in relation to breast cancer incidence was assessed using multivariable adjusted models.

In the multivariable model, participants were stratified by age in months, cohort, and calendar year. This was then adjusted for race, age at menarche, age at menopause, postmenopausal hormone use, history of oral contraceptive use, parity, age at first birth, breastfeeding history, family history of breast cancer, history of biopsy-confirmed benign breast disease, height, neighbourhood-based socioeconomic status indicator, cumulatively updated alcohol intake, physical activity, and BMI at age 18.

During >30 years of follow-up, 12,352 incident invasive breast cancer cases, including 1,703 estrogen receptor (ER)-negative and 7,880 ER-positive breast cancers, were reported. [SABCS 2025, abstract RF1-07]

In the multivariate analysis, higher consumption (>5–6 servings/week) of cruciferous vegetables was associated with a significantly lower risk of breast cancer compared with lower intake (<1 serving/week; hazard ratio [HR], 0.92, 95 percent confidence interval [CI], 0.86–0.97; p-trend<0.01). The strongest association was observed for ER-negative tumours (HR, 0.87, 95 percent CI, 0.74–1.02; p-trend=0.01).

However, the association was attenuated after further adjustments were made for the Alternate Healthy Eating Index-2010 without alcohol and cruciferous and vegetable intake (p-trend=0.11).

GLS intake

Participants in the highest quintile of total dietary GLS intake had a lower risk of invasive breast cancer than those in the lowest quintile in the overall cohort (n=11,181; HR, 0.92, 95 percent CI, 0.87–0.98; p-trend<0.01). Similar patterns were observed in the ER-negative (n=1,672; HR, 0.87, 95 percent CI, 0.74–1.02; p-trend=0.03) and ER-positive (n=7,640; HR, 0.93, 95 percent CI, 0.86–1.00; p-trend=0.01) subgroups.

Looking at GLS subtypes, the aliphatic and indolyl subtypes were inversely associated with breast cancer risk (p-trend<0.01 for both). “Not surprisingly, broccoli was one of the primary dietary sources of these compounds. We are currently investigating the impact of individual [cruciferous] vegetables,” Romanos-Nanclares noted.

A potentially modifiable factor

The results indicate that higher consumption of cruciferous vegetables may reduce the risk of breast cancer, especially those that are more likely to be aggressive tumours, noted Romanos-Nanclares. The study also showed an association between dietary GLS intake and a moderately lower risk of breast cancer.

“[Taken together,] these findings contribute to growing literature suggesting a protective effect of a potentially modifiable factor on breast cancer risk,” said Romanos-Nanclares.

She underlined the need for mechanistic research to shed light on the influence of GLS metabolites on tumour development.