Cabbage (Brassica oleracea), a cruciferous vegetable, has been shown to suppress inflammation and improve diabetes in mice. Cabbages are the source of a variety of compounds with suspected or demonstrated breast cancer fighting properties. Red cabbage and Chinese cabbage varieties such as bok choy contain additional beneficial micronutrients.
Cabbage is a source of chemopreventive isothiocyanates, including allyl isothiocyanate (AITC), benzyl isothiocyanate (BITC), erucin, indole-3-carbinol (I3C) and its metabolic product 3,3'-diindolylmethane (DIM), phenethyl isothiocyanate (PEITC) and sulforaphane. In addition, cabbage is a good source of beta-carotene, choline, folate, lupeol and vitamin C. Chinese cabbage is also a good source of apigenin, and is a richer source of erucin than green or white cabbage. Red cabbage contains anthocyanins, which are responsible for its pigmentation and also have anticarcinogenic activity.

Breast cancer-related effects of eating cabbage

Cabbage consumption is associated with reduced breast cancer risk. Cabbage is the source of a variety of compounds with anti-cancer activities. Cabbage has been found to be promote breast cancer apoptosis (a type of programmed cell death), suppress cell cycle progression, and inhibit angiogenesis (the growth of new blood vessels). Furthermore, cabbage has been shown to protect against cell DNA damage. Red cabbage and Chinese cabbage such as bok choy contain additional chemopreventive compounds. Cabbage can increase the beneficial effects of some breast cancer treatments. Cooking cabbage greatly reduces its potential effectiveness in preventing breast cancer or its relapse.

Epidemiological studies

A number of population studies have found a lower risk of breast cancer associated with consumption of one or more cruciferous vegetables. For example, one carefully designed study of Chinese women (who tend to have high Chinese cabbage consumption) found that cruciferous vegetable consumption was associated with significantly reduced breast cancer risk. Another study based on Italian and Swiss populations reported that consuming cruciferous vegetables at least once per week was associated with a 17% lower risk of breast cancer compared with never or only occasionally consuming cruciferous vegetables.

Cabbage can increase treatment effectiveness

DIM and I3C have been shown to enhance the therapeutic efficacy of the chemotherapy drugs Adriamycin (doxorubicin), Taxol (paclitaxel) and Taxotere (docetaxel) in breast cancer cells. For example, the combination of DIM plus Taxol has been reported to increase the death of HER2 overexpressing (HER2+) breast cancer cells more than Taxol alone in one study.
Cabbage component sulforaphane has been shown increase the anti-cancer effects of Adriamycin, cisplatin, 5-Fluorouracil (5-FU), Taxol and Taxotere. For example, the combination of sulforaphane plus cisplatin has been shown to synergistically inhibit key steps of metastatic cellular growth in triple negative (ER-/PR-/HER2-) breast cancer cells.
PEITC has been found to enhance the sensitivity of the breast cancer cells to radiotherapy and Adriamycin. AITC has been reported to reduce Adriamycin-induced heart damage (cardiomyopathy) in a rat model of chemotherapy.
Cruciferous vegetables are recommended during aromatase inhibitor treatment in part because several isothiocyanates have been shown to reduce aromatase expression, thereby helping to block the production of estrogens from androgens within the body. Breast cancer patients taking tamoxifen who also had relatively high cruciferous vegetable intake were less likely to experience a recurrence than tamoxifen users with low consumption in one study.

Important micronutrients in cabbage

Beta-carotene

Women with substantial intake of carotenoids appear to have lower risks of breast cancer and its recurrence than those with low intake, although not all studies have found such links. A Scandinavian study found that dietary (but not supplemental) beta-carotene had a protective effect against lobular breast cancer in postmenopausal women. Another European study reported that high intake of beta-carotene was protective against breast cancer in postmenopausal women using hormone replacement therapy (HRT). The same study also found that dietary beta-carotene was associated with lowered risk of breast cancer in postmenopausal women with relatively high alcohol consumption.
Beta-carotene enhanced the cytotoxicity of Adriamycin in both hormone receptor positive (ER+/PR+) and triple negative (ER-/PR-/HER2-) breast cancer cells in one study. Beta-carotene has also been demonstrated to reduce multidrug resistance in cancer cells.

Red cabbage anthocyanins

At least 36 anthocyanins (natural red pigments) have been identified in red cabbage. Most are related to cyanidin-3-diglucoside-5-glucoside. Cyanidins have been reported to inhibit the growth and metastasis of breast cancer cells. For example, cyanidin-3-glucoside has been shown to promote the apoptosis of triple negative cells.

Apigenin in Chinese cabbage

Bok choy and other types of Chinese cabbage are a good source of apigenin, which has been found to induce apoptosis across a variety of breast cancer cell lines. For example, apigenin has been shown to exhibit potent growth-inhibitory effects in HER2+ breast cancer cells. Apigenin has also been shown to inhibit the growth of patient-derived triple negative organoids and sensitize triple negative cells to Adriamycin chemotherapy. In addition, apigenin has been shown to lessen Adriamycin-induced kidney damage without reducing its cytotoxic effects against tumor cells in a mouse model of breast cancer.

Cabbage isothiocyanates

Urinary isothiocyanate levels have been found to be related to lower breast cancer risk among both premenopausal and postmenopausal women.
AITC
Oral administration of AITC has been demonstrated to restore levels of proliferation and aromatase activity to near normal levels in a rat model of breast cancer. Another rat study found that AITC prevented mammary tumor angiogenesis and invasion. A 2021 study reported that AITC induced ER+/PR+ breast cancer cell death in a dose-dependent manner by causing DNA damage and altering DNA damage repair proteins.
BITC
Cabbage is the most abundant common food source of BITC. BITC has been found to induce cell death in both ER+/PR+ and triple negative breast cancer cells. BITC has also been shown to inhibit self-renewal of breast cancer stem cells and to reduce mammary tumor development in a mouse model of HER2+ breast cancer.
Erucin
Erucin is more present in bok choy and other types of Chinese cabbage than in white or green cabbage. In fact, the most abundant sources of erucin are arugula, kohlrabi and Chinese cabbage. Erucin has been shown to inhibit the growth and proliferation of ER+/PR+ breast cancer cells.
I3C and its metabolic product DIM
Numerous studies have reported that I3C and DIM reduce the growth, proliferation and migration of various types of breast cancer cells. For example, I3C has been shown to inhibit proliferation of estrogen receptor positive (ER+) breast cancer cells. I3C/DIM has also been shown to inhibit aromatase (the conversion of androgens to estrogens) in both normal and ER+/PR+ breast cancer cells at concentrations in the range of that observed in human plasma.
DIM has been shown to inhibit the growth of transplanted human breast cancer cells in mice. In a separate study, DIM administered to mice injected with cancer cells caused a marked reduction in the number of lung metastases.
PEITC
PEITC (whose richest source is watercress) has been shown to reduce the growth of human breast cancer cells and decrease angiogenesis (the process by which tumors send out signals to induce surrounding normal tissues to grow new blood vessels into the tumor). In addition, PEITC has been demonstrated to inhibit the growth of HER2+ mammary tumors in mice and inhibit metastasis to the brain in a mouse model of breast cancer.
Sulforaphane
Sulforaphane has been shown to reduce triple negative breast cancer growth. A relatively low concentration of sulforaphane has been demonstrated to preferentially eliminate breast cancer stem cells from triple negative cells.
Mice were implanted with breast cancer tumors and the tumors were treated directly with sulforaphane in one experiment. Daily injection with sulforaphane for two weeks was found to reduce the number of stem cells by more than 50% in the xenograft tumors.
Sulforaphane has also been shown to inhibit aromatase in both normal and ER+/PR+ breast cancer cells at concentrations in the range of that observed in human plasma.
Sulforaphane has also been demonstrated to inhibit Herceptin-resistant HER2+ breast cancer.

Additional comments

Raw or lightly cooked cabbage is best

Isothiocyanates are obtained from glucosinolates when the enzyme myrosinase is released from damaged plant cells. Myrosinase is physically separate from glucosinolates in intact plant cells. Chewing or chopping a cruciferous vegetable enables the myrosinase to catalyze the reaction that converts its glucosinolates into isothiocyanates. This is part of the plant defense mechanism which is triggered when, for example, an animal chews the plant. The process of conversion to isothiocyanates is halted when cruciferous vegetables are cooked, although human intestinal bacteria facilitate some formation and absorption of isothiocyanates.
Ideally, cabbage should be consumed raw or chopped and then lightly cooked (by stir-frying, steaming, or microwaving) for a short period of time in a small amount of water. Raw cabbage is a far superior source of isothiocyanates than boiled cabbage. One study reported that 56% of the glucosinolate content of cabbage is lost after two minutes of boiling.

Kohlrabi

Kohlrabi is closely related to cabbage and is a good source of AITC, erucin, PEITC, and sulforaphane. Both the leaves and the bulb-like stem are edible, although the bulb should be peeled.

Sauerkraut

Frequent consumption of raw or short-cooked sauerkraut has been reported to be associated with significantly lower breast cancer risk. Recent research suggests that microorganisms found within the gut, and gut microbial imbalances in particular, can influence breast cancer risk and development. The gut microbiome is defined as the complete sets of genes or genetic material present in these microorganisms. Consumption of fermented vegetables has been shown to beneficially increase the diversity of the gut microbiome, even after a relatively short period of time.

Kimchi

Kimchi is a Korean condiment most often made from fermented Chinese cabbage, plus a mix of seasonings. Kimchi should be consumed in moderation. While kimchi shares many of the chemopreventive attributes of cabbage and sauerkraut, it typically incorporates ingredients such as ethyl carbamate and high levels of salt and hot red pepper that have been linked to stomach cancer at high levels of consumption.

Cruciferous vegetable supplements are not recommended

Unlike some other anti-cancer compounds found in foods, those in cruciferous vegetables are relatively bioavailable and meaningful amounts can be obtained through the diet. We recommend consuming cabbage and other cruciferous vegetables as food and against taking "broccoli pills" or other supplements that have been formulated to contain the key anti-cancer chemicals in these vegetables.
There is some evidence that concentrated cruciferous vegetable extracts can act as estrogen agonists and promote ER+ breast cancer cell proliferation. For example, one study reported that while physiologically achievable doses of I3C reduced aromatase expression of ER+/PR+ breast cancer cells, higher doses induced its expression.
Also, the anticancer properties of cabbage are likely to be the result of synergistic interaction of its various chemical components - isolated components have successfully inhibited proliferation in the laboratory, but their efficacy and safety in humans needs to be evaluated in large scale clinical trials.

Sources of information provided in this webpage

The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.
Below are links to 20 recent studies concerning this food and its components. For a list of studies that includes older research, please click on cabbage.