Looking for the most powerful cancer-fighting vegetables on the planet? Then feast your eyes (and of course, your body) on the plant foods that have demonstrated the most dramatic protection against cancer: the cruciferous family of vegetables.
With their spicy, sometimes bitter taste (thanks to their glucosinolate content – more on that later), cruciferous vegetables add a depth of flavor to a healthy diet, in addition to their beneficial properties. The list of cruciferous veggies includes: arugula, bok choy, broccoli, broccoli rabe, broccolini, brussels sprouts, cabbage, cauliflower, collards, horseradish, kale, kohlrabi, mustard greens, radish, red cabbage, rutabaga, turnips, turnip greens, and watercress. You’ll find almost all of them are included in my 100 Best Foods for Health and Longevity.
The cruciferous family is unique among vegetables because of their glucosinolate content. When the plant cell walls are disrupted by chewing, chopping, or blending, the enzyme myrosinase converts glucosinolates to isothiocyanates (ITCs) or indole-3-carbinol. Scientific studies have uncovered cellular and molecular anti-cancer effects of these cruciferous phytochemicals, and a lower risk of cancer in people who eat these vegetables regularly.
To get the maximum benefit from cruciferous vegetables, it’s important to make sure you chop finely, blend, or crush them before you cook them, or chew them well when eating them. That’s because the myrosinase enzyme is physically separated from the glucosinolates in the intact vegetables. But when the plant cells are broken apart, the chemical reaction occurs and ITCs are formed. The more cells you break open before cooking (or chew if you are eating the vegetables raw), the better.
Once ITCs are formed, they will remain stable through the cooking process. Gut bacteria also have some myrosinase enzyme, so additional ITC production from glucosinolates in cooked cruciferous vegetables may occur after we eat them. Also, we can increase ITC production from cooked cruciferous vegetables by having some shredded raw cruciferous vegetables such as cabbage, kale, collards or arugula in a salad in the same meal to supply the myrosinase enzyme, which the body can use during the digestive process.1-3
Disposition of glucosinolates and sulforaphane in humans after ingestion of steamed and fresh broccoli
Hydrolysis before Stir-Frying Increases the Isothiocyanate Content of Broccoli
Isothiocyanates from Brassica Vegetables-Effects of Processing, Cooking, Mastication, and Digestion
Higher intake of cruciferous vegetables is linked to a reduced risk of cancers of the lung, ovary, stomach, breast, prostate, and colon.4-8
The Role of Cruciferous Vegetables and Isothiocyanates for Lung Cancer Prevention: Current Status, Challenges, and Future Research Directions
Intake of cruciferous vegetables is associated with reduced risk of ovarian cancer: a meta-analysis
Cruciferous vegetables intake and the risk of colorectal cancer: a meta-analysis of observational studies
Cruciferous vegetable consumption and gastric cancer risk: a meta-analysis of epidemiological studies
Cruciferous vegetables intake is inversely associated with risk of breast cancer: a meta-analysis
Indole-3-carbinol (abundant in broccoli, Brussels sprouts and cabbage) and ITCs have anti-estrogenic effects, help the body excrete estrogen and other hormones.11 In fact, new research has shown additional anti-estrogenic effects of both indole-3-carbinol and sulforaphane (most abundant in broccoli); these ITCs blunt the growth-promoting effects of estrogen on breast and cervical cancer cells.11-13
Studies have found breast cancer survivors who eat cruciferous vegetables regularly have a lower likelihood of cancer recurrence.14,15
Anti-estrogenic activities of indole-3-carbinol in cervical cells: implication for prevention of cervical cancer
Indole-3-carbinol is a negative regulator of estrogen receptor-alpha signaling in human tumor cells
Regulation of estrogen receptor alpha expression in human breast cancer cells by sulforaphane
Cruciferous Vegetable Intake After Diagnosis of Breast Cancer and Survival: a Report From the Shanghai Breast Cancer Survival Study
Vegetable intake is associated with reduced breast cancer recurrence in tamoxifen users: a secondary analysis from the Women's Healthy Eating and Living Study
In healthy people, randomized controlled trials have found decreases in oxidative stress or increases in antioxidant enzymes after consumption of cruciferous vegetables.16-19
Phase 1 study of multiple biomarkers for metabolism and oxidative stress after one-week intake of broccoli sprouts
Reduction of oxidative DNA-damage in humans by brussels sprouts
Effect of broccoli intake on markers related to oxidative stress and cancer risk in healthy smokers and nonsmokers
Watercress supplementation in diet reduces lymphocyte DNA damage and alters blood antioxidant status in healthy adults
Reduced cancer-related biomarkers have been found in randomized controlled trials on supplementation with cruciferous vegetables or their extracts in patients with prostate cancer or breast cancer.20-23
Effect of Sulforaphane in Men with Biochemical Recurrence after Radical Prostatectomy
Broccoli consumption interacts with GSTM1 to perturb oncogenic signalling pathways in the prostate
Effect of Cruciferous Vegetable Intake on Oxidative Stress Biomarkers: Differences by Breast Cancer Status