Consumption of Glucoraphanin-Rich Broccoli Soup Slows Progression of Prostate Cancer

by | Jul 28, 2020 | 2019, Cancer, Men's Health - Prostate

Written by Angeline A. De Leon, Staff Writer. Consumption of glucoraphanin-rich broccoli soup was inversely associated with prostate cancer progression in men on active surveillance.

broccoliAmong men who are diagnosed with organ-confined prostate cancer, nearly half of all cases are associated with subsequent disease progression, with a smaller percentage leading to metastatic cancer 1,2. Recent epidemiological evidence suggests that dietary intake of cruciferous vegetables (e.g., broccoli, cauliflower, cabbage) may help reduce the incidence or acceleration of prostate cancer 3,4. This effect has been attributed to the biological activity of glucosinolates (sulfur-containing compounds associated with bitter taste and pungent aroma) found in cruciferous vegetables 5. When broken down in the body, glucosinolates are known to exhibit protective effects related to stress response, antioxidant activity, and inflammation regulation 6. Accordingly, consumption of cruciferous vegetables has been shown to be effective in mitigating chronic age-related diseases 7. Broccoli sprouts, specifically, appear to reduce prostate cancer incidence by regulating histone deacetylation 3 (key role in prostate cancer progression) and by influencing gene expression of prostate cells 8. In order to explore the potential efficacy of a diet-based approach to controlling prostate cancer, a 2019 study 9 in the American Journal of Clinical Nutrition tested the effects of consuming broccoli soup containing enhanced levels of glucoraphanin (glucosinolate found in broccoli) on gene expression in the prostate tissue of patients with localized prostate cancer.

A randomized, double-blind, 3-arm parallel-group trial was carried out with a total of 49 men (mean age = 66.67 years) with a diagnosis of low- or intermediate-risk prostate cancer who were undergoing active surveillance. Patients were randomly assigned to consume 300 mL of standard broccoli soup (control), broccoli soup containing glucoraphanin concentrations 3 times greater than that of control (intermediate-GR), or broccoli soup containing glucoraphanin concentrations 7 times greater than that of control (high-GR) once weekly for 12 months. At baseline and at 1-year follow-up, patients completed a prostate biopsy procedure. Tissue samples were analyzed for changes in gene expression using RNA sequencing and gene set enrichment analyses.

Based on results, glucoraphanin intake appeared to be associated with a suppression of changes in gene expression: the control group exhibited several hundred changes in gene expression over the 12-month period while the intermediate-GR group showed only modest changes (relative to control) and the high-GR group showed a significant change in the expression of only a single gene (p < 0.05). Gene set enrichment analyses also indicated that the high-GR group exhibited a lack of significant enrichment of carcinogenic pathways (inflammatory response and epithelial-mesenchymal transition pathways), relative to the control group. Finally, exploratory analyses revealed an inverse correlation between dietary intake of cruciferous vegetables at baseline and prostate cancer progression over the study period (based on changes in World Health Organization grade) (r = -0.32).

Findings indicate that a dietary intervention with glucoraphanin, in the form of broccoli soup, is associated with attenuation of changes in gene expression in the prostate of male patients on active surveillance. Gene set enrichment analyses indicated that higher levels of glucoraphanin may contribute to the inhibition of transcriptional changes associated with oncogenic pathways, confirming a lowered risk of cancer progression with intake of cruciferous vegetables. This was corroborated by a negative association between dietary intake of cruciferous vegetables and cancer progression over the study period. The chemopreventative effects observed in the present study may involve an epigenetic regulation effect, however, further research is needed to verify the precise mechanisms associated with glucoraphanin’s effects. Limitations of the study relate to its relatively small sample size and the transcriptional profiling of non-neoplastic prostate biopsies.

Source: Traka MH, Melchini A, Coode-Bate J, et al. Transcriptional changes in prostate of men on active surveillance after a 12-month glucoraphanin-rich broccoli intervention-results from the Effect of Sulforaphane on prostate CAncer PrEvention (ESCAPE) randomized controlled trial. Am J Clin Nutr. 2019; 109: 1133-1144. DOI: 10.1093/ajcn/nqz012.

© American Society for Nutrition 2019. All rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/)

Click here to read the full text study.

Posted July 28, 2020.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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