Turnips (Brassica rapa subsp. rapa) and turnip greens have been shown to have antioxidant and anti-inflammatory properties. Turnips are a source of the chemopreventive isothiocyanates benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC), as well as some sulforaphane. Turnips are also a source of vitamin C.
Turnip greens, which are more nutritious than turnips, are a source of the isothiocyanates indole-3-carbinol (I3C) and its metabolic product 3,3'-diindolylmethane (DIM), phenethyl isothiocyanate (PEITC), and also some sulforaphane. In addition, turnip greens are a good source of beta-carotene, folate, kaempferol, and quercetin, and also contain vitamin C and vitamin K.
Breast cancer-related effects of eating turnips and turnip greens
Turnip and turnip green consumption is associated with reduced breast cancer risk. The turnip plant is the source of a variety of compounds with anti-cancer activities. Various isothiocyanates derived from turnips or turnip greens have been found to have anti-cancer activity against a variety of breast cancer cell lines in the laboratory as well as chemopreventive activity in animal studies. Generally speaking, turnips and turnips green are less chemopreventive than other cruciferous vegetables and greens.
Epidemiological studies
A Chinese study which measured urinary isothiocyanate levels as a marker of cruciferous vegetable intake found that higher levels were protective against breast cancer in both premenopausal and postmenopausal women. Turnip consumption has been found to be associated with lower risk of breast cancer in U.S., Chinese, Japanese, and Korean women.
Turnip compounds 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.
Turnip green 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. Turnip green compound kaempferol has been shown to reduce the degree of heart and kidney damage caused by Adriamycin in rat models of chemotherapy.
Beta-carotene enhanced the cytotoxicity of Adriamycin in both hormone receptor positive (ER+/PR+) and triple negative breast cancer cells in one study. Beta-carotene has also been demonstrated to reduce multidrug resistance in cancer cells.
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 turnip micronutrients
Turnip isothiocyanates
Urinary isothiocyanate levels have been found to be related to lower breast cancer risk among both premenopausal and postmenopausal women.
BITC - Turnips
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.
I3C and its metabolic product DIM - Turnip greens
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 - Turnips & turnip greens
PEITC 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 - Turnips & turnip greens
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.
Other turnip green micronutrients
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.
Folate
Dietary folate (but not folic acid) intake is associated with reduced risk of breast cancer recurrence, especially among women with estrogen receptor negative (ER-) tumors. Co-treatment with progesterone abolished progesterone-induced breast cancer proliferation and migration in one cell study.
Kaempferol
Diets abundant in kaempferol have been found to be associated with reduced breast cancer risk. Kaempferol has been shown to inhibit the growth of ER+/PR+ breast cancer cells, in part through inhibition of glucose uptake. Kaempferol has also been found to inhibit both primary tumor growth and lung metastasis in a mouse model of breast cancer. In addition, kaempferol may protect against the cancer-promoting effects of triclosan, an antibacterial chemical to which most people are routinely exposed which is an endocrine disruptor.
Quercetin
Quercetin has been shown to increase the effectveness of both Adriamycin and Taxol in multidrug resistant ER+/PR+ breast cancer cells, in part by eliminating cancer stem cells. Quercetin has also been shown to inhibit the migration and adhesion of triple negative (ER-/PR-/HER2-) breast cancer cells and to significantly inhibit tumor progression in a mouse model of triple negative breast cancer.
Additional comments
Turnips and turnips greens should be consumed in moderation
Turnips and turnip greens should be consumed in moderation because they contain some isothiocyanate-related compounds that are considered anti-nutritional instead beneficial. For example, they are significant sources of goitrogenic thioglucoside compounds that can interfere with the formation of thyroid hormone.
Rutabagas, radishes & rapini
Rutabagas (also know as yellow turnips or swedes) are closely related to turnips and appear to have similar chemopreventive properties, although they are a better source of myricetin. Radishes (another type of cruciferous vegetable also related to turnips) are a good source of isothiocyanates such as allyl isothiocyanate (AITC). Rapini (Brassica rapa ruvo), or broccoli rabe, is a cruciferous vegetable that resembles small heads of broccoli but is more closely related to turnips than broccoli.
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 vegetable and its components. For a more complete list, including less recent studies, please click on turnips and turnip greens.