Cruciferous vegetables, Cancer and Estrogen metabolism
Consumption of cruciferous vegetables – a family of vegetables that includes spinach, watercress, radish, cabbage, broccoli, cauliflower, Brussels sprouts and kale – has long been associated with good health. A highly significant study from the University of Ulster was published that adds to the growing body of evidence linking the consumption of these vegetables to a reduced risk of developing cancer. (1)
Fruits and vegetables contain many biologically active compounds (phytochemicals) that help prevent free radical formation, remove free radicals, repair damage and prevent mutations. The components of plants have both complementary and overlapping mechanisms of action. Cruciferous vegetables are a rich source of compounds known as glucosinolates which are metabolised when the plant cell walls are broken down by chewing, to compounds such as indoles and isothiocyanates (ITC). It is these metabolites that are thought to be the factor linking these vegetables to a decreased risk of DNA damage. Different cruciferous vegetable groups produce distinct metabolites.
A metabolite of broccoli and brussels sprouts – indole-3 carbinol, which is further broken down to diindolylmethane (DIM), is thought to increase sex hormone clearance in the liver and has been linked to reduced risk of pre-menopausal breast cancer. DIM is thought to induce growth arrest and promote apoptosis in response to DNA damage; oestrogen by contrast promotes the growth of tumours. Supplementation with DIM alters urinary oestrogen metabolite profiles in women. (4)
A further study of 740 women with breast cancer and 810 control women, found that consumption of cruciferous vegetables, broccoli in particular, was inversely associated with breast cancer risk in pre-menopausal women (2). This may be due to effects on estrogen metabolism. (3)
Given the numerous studies now that outline the cancer protective qualities of cruciferous vegetables, I would advise that anyone with a family history of cancer or those with a previous history of cancer should adopt at least 1-2 portions of cruciferous vegetables daily. Some evidence also suggests that increased fat storage in the lower body, especially the thighs and buttocks can also be an indication of faulty estrogen metabolism or hormone clearance. If you are interested in adding more cruciferous vegetables to your diet, remember that eating them raw or lightly steamed is the best way to retain their phytochemicals and other anti-cancer compounds. Cruciferous vegetables tend to be better digested if they have been cooked as many may experience bad wind and sometimes stomach cramps from raw cruciferous vegetables.
One of the most prominent causes of breast cancer, as well as many other hormone-related health problems in both men and women, is excessive estrogen exposure from both endogenous and exogenous sources.
Endogenous estrogen is the female sex hormones the body produces as part of the menstrual cycle.
Exogenous oestrogens are environmental compounds with hormone-like action on human development and reproductive health, these sources can include:
- Non-organic meat that has been exposed to hormones to increase their size and weight (mainly in the US).
- Car exhaust fumes.
- Plastics, especially those found to package food.
- Some emulsifiers found in soaps and cosmetics.
- Many herbicides, pesticides and fungicides.
- Oral contraceptives and synthetic hormone replacement therapy
The metabolism of estrogens takes place primarily in the liver. The process which occurs during phase 1 metabolism in the liver converts estrogens into either 2-Hydroxylation (good estrogens) or 4- or 16-alpha-hydroxyoestrone (bad estrogens).
Health conditions associated with estrogen dominance or imbalance.
- Dysmenorrhoea – painful menstruation (lower abdominal cramping, headaches, constipation, nausea, vomiting, diarrhoea).
- Endometriosis – The lining of the womb (the endometrium) implants and grows outside of the womb itself; this can cause extremely painful heavy/irregular periods, GI problems and infertility.
- Fibroids – Non-cancerous growths in or on the muscular wall of the womb, which may cause heavy periods, pain, infertility, continual menstruation.
- Premenstrual Syndrome (PMS) – Any symptoms that occur after ovulation and disappear almost as soon as menstrual bleeding starts. Include mood swings, irritability, anxiety & tension, bloating, tiredness and depression.
- Polycystic Ovary Syndrome (PCOS) – Ovarian follicles are much larger than normal and a number of undeveloped follicles appear in clumps. The cysts can cause hormonal imbalance leading to a series of other symptoms.
Nutritional Factors that may positively influence oestrogen metabolism
- Dietary Fibre
- Omega-3 fatty acids
- Vitamin D
- Vitamin E
- B vitamins
- Indole-3-Carbinol (I3C) & Diindolylmethane (DIM)
- Cruciferous Vegetables
This group of vegetables naturally help in the production of indole and DIM. They are also a rich source of phytochemicals that have been associated with many health benefits. Cruciferous vegetables are important in enabling the body to metabolise excess oestrogen.
Cruciferous vegetable sources
- Brussels sprouts
- Daikon radish
- Mustard/chard greens
- Gill CI, Haldar S, Boyd LA, Bennett R et al Watercress supplementation in diet reduces lymphocyte DNA damage and alters blood antioxidant status in healthy adults Am J Clin Nutr. 2007 Feb;85 (2):504-10
- Higdon JV, Delage B, Williams DE, Dashwood RH Cruciferous vegetables and human cancer risk:epidemiologic evidence and mechanistic basis, Pharmacol Res. 2007 Jan 25 (pub ahead of print online)
- Ambrosone CB, McCann SE, Freudenheim JL, Marshall JR et al Breast cancer risk in pre-menopausal women is inversely associated with consumption of broccoli, but is not modified by GST genotype. J Nutr. 2004 May;134(5):1134-8
- Auborn KJ, Fan S, Rosen EM, Goodwin, L Indole-3-carboinol is a negative regulator of oestrogen, J Nuti.2003 Jul;133 (7Suppl) :2470S-2475S
- Nutri Instant Expert, Female Hormone Health