Cruciferous vegetables and cancer
Cruciferous vegetables, part of the Brassicaceae family, include popular options such as broccoli, cauliflower, kale, and Brussels sprouts. These vegetables are notable for their rich content of glucosinolates, which are sulfur-containing compounds that may contribute to their potential cancer-fighting properties. Research suggests that regular consumption of these vegetables may lower the risk of several cancers, including lung, prostate, and colorectal cancer. The beneficial effects are thought to arise from bioactive compounds like isothiocyanates and indole-3-carbinol, formed when these vegetables are chopped or chewed.
Epidemiological studies, including a 2023 analysis from UCLA, indicated a protective effect against various cancers for individuals who consume cruciferous vegetables regularly. However, the precise mechanisms and the role of individual genetic variability in cancer risk are still being explored. While incorporating cruciferous vegetables into one's diet is generally encouraged, potential side effects, such as digestive discomfort and thyroid issues with excessive intake, should also be considered. The National Cancer Institute recommends consuming five servings of cruciferous vegetables weekly for optimal health benefits, aligning with broader dietary guidelines to fill half of one's plate with fruits and vegetables.
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Subject Terms
Cruciferous vegetables and cancer
ALSO KNOWN AS: Brassicaceae family, glucosinolates, isothiocyanates, indole-3-carbinol
DEFINITION: Cruciferous vegetables are edible plants from the Brassicaceae family. They include broccoli, cauliflower, Brussels sprouts, cabbage, arugula, watercress, bok choy, turnip and mustard greens, kale, kohlrabi, turnips, rutabagas, and radishes. Cruciferous vegetables contain various healthy substances such as vitamin C, selenium, fiber, and sulfur-containing compounds called glucosinolates. The sulfur compounds give cruciferous vegetables their pungent taste and aroma.
Cancers treated or prevented:colorectal cancer, lung cancer, prostate cancer
Delivery routes: Oral by diet
How these compounds work: Cruciferous vegetables are rich sources of glucosinolate compounds, which may be the source of their cancer-fighting effects. When the vegetables are chopped or chewed, bioactive hydrolysis products of glucosinolates, such as isothiocyanates and indole-3-carbinol, are formed. These compounds may help prevent certain cancers by eliminating dietary carcinogens from the body or by preventing normal cells from becoming cancerous. Cooking or boiling cruciferous vegetables decreases the amount and bioavailability of glucosinolates, so raw vegetables provide much higher levels of the compounds than cooked vegetables.
Higher intakes of cruciferous vegetables have been linked to a lower risk of lung cancer, prostate cancer, and colorectal cancer in epidemiological studies. In 2012, C. Bosetti et al. published the result of their analysis of the effect of cruciferous vegetable consumption in a large network of case-control studies of various cancers in Annals of Oncology. The studies showed additional evidence that cruciferous vegetable consumption had a favorable effect on some common cancers. In 2014, the American Society of Clinical Oncology reported consuming cruciferous vegetables helped protect against cancers of the mouth, larynx, pharynx, esophagus, and stomach. Evidence was limited, however, and the effects were not consistent. In addition, it is not clear whether the beneficial effects of cruciferous vegetables come from the glucosinolate compounds or from other phytochemicals that act synergetically. Still, as research continued, studies produced additional evidence of cruciferous vegetables' ability to prevent cancer. In a study publish in 2023, researchers at the University of California - Los Angeles found that patients consuming cruciferous vegetables regularly, especially broccoli, had a lower risk for prostate, breast, colon, and oral cancers. Cancer prevention was just one health benefit among many.
Genetic variability may influence the effects of cruciferous vegetables on cancer risk. For example, individuals may vary in their capacity to absorb, metabolize, and eliminate glucosinolate compounds from the body. Thus, genetic differences that affect how long these compounds or their metabolites remain in the body may influence how protective they are against cancer. The National Cancer Institute recommends the daily consumption of between two and six cups of fruits and vegetables; human epidemiological studies suggest five weekly servings of cruciferous vegetables are beneficial. As part of the US Department of Agriculture’s MyPlate program for daily food guidelines, the agency suggests that half of one’s plate should be made up of fruits and vegetables.
Side effects: Very high intakes of cruciferous vegetables may cause hypothyroidism. In addition, some of the isolated metabolites of glucosinolates in cruciferous vegetables, such as indole-3-carbinol, have produced mixed results in animal studies. For example, depending on when the compound is administered or the length of exposure, indole-3-carbinol can prevent or promote the development of cancer in animals. These studies highlight the disadvantages of isolating potentially beneficial compounds from food, as isolated compounds may produce unwanted effects, and the synergy of many compounds may be critical in cancer prevention. Consuming cruciferous vegetables can also have digestive side effects, including bloating and gas. Their high content of vitamin K may be problematic for people with blood-clotting issues.
Bibliography
Bosetti, C., et al. “Cruciferous Vegetables and Cancer Risk in a Network of Case–control Studies.” Annals of Oncology, vol. 23, no. 8, Aug. 2012, pp. 2198-2203. Elsevier, www.annalsofoncology.org/article/S0923-7534(19)38110-4/fulltext. Accessed 18 June 2024.
Champion, Chayil. “Broccoli and other Cruciferous Veggies Can Significantly Lower Cancer Risks.” UCLA Health, 29 Dec. 2023, www.uclahealth.org/news/article/broccoli-and-other-cruciferous-veggies-can-significantly-lower-cancer-risks. Accessed 18 June 2024.
“Cruciferous Vegetables and Cancer Prevention.” National Cancer Institute, 7 June 2012, www.cancer.gov/about-cancer/causes-prevention/risk/diet/cruciferous-vegetables-fact-sheet. Accessed 18 June 2024.
DiNoia, Jennifer. “Preventing Chronic Disease - Defining Powerhouse Fruits and Vegetables: A Nutrient Density Approach.” CDC, 5 June 2014, www.cdc.gov/pcd/issues/2014/13‗0390.htm. Accessed 18 June 2024.
“Fruit and Vegetable Consumption.” Cancer Trends Progress Report, Mar. 2024, progressreport.cancer.gov/prevention/fruit‗vegetable. Accessed 18 June 2024.
Pajari, Anne-Maria, and Marja Mutanen. Vegetables, Whole Grains, and Their Derivatives in Cancer Prevention. Dordrecht: Springer, 2011.
US Dept. of Agriculture, and US Dept. of Health and Human Services. Dietary Guidelines for Americans 2010. 7th ed. Washington, DC: US GPO, 2010.
Vanderbilt University Medical Center. "Eating Cruciferous Vegetables May Improve Breast Cancer Survival." Science Daily, 3 Apr. 2012, www.sciencedaily.com/releases/2012/04/120403153531.htm. Accessed 18 June 2024.