In several (laboratory) experiments the broccoli ingredient sulforaphane shows activity against highly aggressive cancer stem cells of pancreas and prostate. Recently the University of Heidelberg published data which are in the meanwhile confirmed by other researchers in breast and prostate cancer. Their data are supported by epidemiological studies, in which nutritional habits of large population groups with respect to cancer risk and progression of cancer have been evaluated.
Although the present data are promising, they can only be transferred to the clinical treatment of cancer patients, if positive data from clinical trials are available. In the United States clinical trials with broccoli sprouts are ongoing since 2012 to examine the effect of sulforaphane to precursor lesions of malignant melanoma, prostate and bladder cancer. In Heidelberg preparations for initiation of a pilot study are ongoing to evaluate the effect of broccoli sprouts to 40 patients with advanced pancreatic cancer, which are treated at the Department of General and Transplantation Surgery of the University of Heidelberg. Half of the patients will receive chemotherapy and broccoli sprouts the other half will receive chemotherapy and a placebo, followed by evaluation of quality of life, tumor marker expression, tumor growth and survival. The realization of this study was enabled by a donation of the Heidelberger Stiftung Chirurgie and Norbert Deiters (Deiters & Florin). Independently of this study you may uptake sulforaphane easily via nutrition. In the following you will find information about sulforaphane-containing food and further interesting data to nutrition and cancer.
General Information to Sulforaphane
Since the ancient the beneficial effects of cruciferous vegetables have been used therapeutically. This plant family contains e.g. broccoli and cauliflower, all cabbage types, but also cress, nasturtium, rucola, radish, horseradish, canola and mustard. In the meantime, the active ingredients of the cruciferous vegetables have been identified as mustard oil glycosides, of which more than 150 different are known. These are present in different amounts in the numerous representatives of cruciferous vegetables. They are responsible for the sharp taste of radish, horseradish and mustard or the partially bitter taste of different cabbage species. One of the most famous and best-studied mustard oil glycosides is glucoraphanin. Glucoraphanin is cleaved into the active substance sulforaphane, which we used for our experimental studies. Sulforaphane is not yet available as pure substance in a medicament. However, you may uptake sulforaphane by diet in therapeutically active concentrations. A prospective epidemiological nutrition study with prostate cancer patients demonstrates that frequent intake of broccoli or cauliflower (3-5 servings per week) significantly reduces the risk for invasion of the tumor to 50%. Other epidemiological studies show a cancer preventive effect of high cabbage intake. Numerous scientific examinations demonstrate that sulforaphane and related mustard oils help to fight inflammation and infections with bacteria and viruses and inhibit tumor growth. Recent data also show a positive influence of cabbage to the gut microbiome. A healthy gut microbiome is essential to strengthen the immune system and thus improved tumor defense.
Sulforaphane Against Tumor Stem Cells
We were the first worldwide who demonstrated in laboratory experiments and in mice that sulforaphane attacks the particularly aggressive tumor stem cells in experimental models of pancreatic cancer and thereby sensitize them for chemotherapy. According to the hypothesis tumor stem cells are responsible for growth and metastasis of cancer. They survive current chemo- and radiotherapies. Since the normal tumor cells are sensitive, they die under therapy and thus the tumor often shrinks during the first therapy cycles. However, the small population of resistant tumor stem cells remains viable and is made responsible for re-growth of the tumor. We even see that tumor stem cells are enriched during repeated chemotherapeutic treatment and therefore the tumor becomes completely resistant after several treatment cycles. A nutrition rich in sulforaphane-containing vegetables may counteract enrichment of tumor stem cells.
Exact Dosage of Sulforaphane in Patients is Unknown
If the effective one-time dosage of sulforaphane in mice is converted to an equivalent dose in humans based on the body-surface this results in 0.36 mg sulforaphane per kg body weight or: 25.2 mg Sulforaphane for a Person Weighing 70 kg. This dosage was calculated according to a formula, which is used by a veterinarian to calculate drug doses for different animal species. The number of 25.2 mg sulforaphane obtained is about factor 10 lower than than a dose, which is calculated directly from the body weight of the mouse to human. In just initiated clinical trials in the United States for treatment of precursors of malignant melanoma, prostate and bladder cancer 88 mg sulforaphane will be administered daily for several weeks. In our scheduled pilot study for pancreatic cancer 90 mg sulforaphane in the form of broccoli sprouts in 15 capsules will be daily administered for one year. We do not know which exact dose could be properly for therapy of cancer patients. Epidemiological studies indicate that a salutary dose of sulforaphane and related mustard oils may be administered by regular nutrition rich in vegetable of the cruciferous family.
Consumption of Sulforaphane via Cabbage and Broccoli Sprouts
The valuable ingredients of cruciferous vegetables are best obtained when they are eaten raw and chewed well, or if they are shortly steam-cooked or sauted. Sulforaphane is water-soluble, that means the cooking water should not been thrown away, but used for a sauce or soup. A very good source for sulforaphane are broccoli sprouts since they contain 10-100 times more sulforaphane than a broccoli head – dependent on species and growth conditions. You may germinate broccoli seeds yourself or use commercially available freeze-dried broccoli sprouts.
Commercially available sulforaphane products have typical concentrations of 2.5 to 10 mg pure sulforaphane per capsule or a comparable amount of seedling shotgun. Please contact the manufacturer for detailed concentrations. Please understand that we cannot provide calculations for concentrations and do recommend manufacturers for broccoli products. We are molecular biologists and are not involved in testing these products.
Self-breeding of Sprouts for Herbed Quark, Salad, Sandwiches
For self-breeding of broccoli sprouts simple clay coasters or special glasses for sprouts may be suited. More decorative may be a sprouting hedgehog, which is offered for example from the german company Römertopf. In addition, there are multistory germ units made of plastic or clay. Sprouting devices may be obtained from health-foodsShops or from online shops.
At these companies you will also find suited seeds for sprouts. Please do not restrict sprout breeding to broccoli. Salutary effects have been detected also for other members of the crucifers, e.g. for mustard, radish, horseradish, cress, nasturtium, arugula, brussels sprouts, cauliflower and green cabbage. Of special interest is the “Brokkoletti” seed derived from a broccoli wild-form, which produces more sulforaphane than cultured broccoli. Very tasty are sprouts from white mustard (sharp), radish (decoratively red) or cress. Attention: Should the sprouts be contaminated (e.g. due to excess of water or too cold temperatures), purify dishes of clay well with a dishwashing brush and by baking in the oven for 45 min, 200°C.
Side Effects of Broccoli Florets and Broccoli Sprouts
Almost everyone knows the flatulent effect of cabbage. Other known effects of cabbage to digestion are due to the two atoms of sulphur in glucosinolates. During break down of cabbage by gut bacteria hydrogen sulphide is produced and responsible for a ‘rotten egg’ odor. Besides, sulforaphane acts as an indirect antioxidant. Antioxidant supplements may help protect normal cells from oxidative damage and reduce the short- and long-term harmful effects of cancer treatment. On the other hand, concern has been raised that antioxidant supplements may also protect tumor cells during radiotherapy and chemotherapy, thereby compromising treatment efficacy. This has resulted in controversy over guidelines for the use of vitamin supplements during cancer treatment. We tested this issue in an experimental human pancreatic cancer xenograft model in mice. We found that sulforaphane increased the effect of gemcitabine, cisplatin, doxorubicin, 5-fluorouracil, sorafenib, TRAIL and quercetin to growth inhibition of tumor xenografts. These laboratory experiments are promising but cannot be directly transferred to the clinic. For a definite statement we need the data of a patient study, in which sulforaphane is administered together with chemotherapy. Regarding broccoli sprouts it should be considered that the sprouts may be contaminated with dangerous gut bacteria or fungi due to the warm and humid germination. In addition to glucoraphanin, broccoli contains the goitrogenic glucosinolates glucobrassicin and progoitrin. However, cabbage does not alter thyroid function in humans unless massive amounts are consumed. Notably, sprouts of many broccoli cultivars contain negligible quantities of glucobrassicin, which predominate in the mature vegetable.
Additional Research with Foods to Fight Cancer Stem Cells
It is increasingly clear that mustard oils and especially sulforaphane possess cancer preventive and therapeutic properties, of which the anti-CSC activity is of special interest. Although we were the first research team worldwide that discovered that sulforaphane eliminates pancreatic cancer stem cell features, ongoing research detected in the meantime other naturally occurring plant substances with anti-CSC activity. Our research shows that the polyphenol quercetin, present in broccoli and many other fruits and vegetables, is also able to eliminate pancreatic CSC characteristics and thereby enhances the effect of sulforaphane. Latest experimental data identified anti-CSC activities in legumes (genistein from soybeans), curcuma (curcumin, contained e.g. in curry), tomatoes (lycopen), grapes, berries, plums and peanuts (resveratrol, e.g. in grape seed oil, red wine), black pepper (piperin), green tea (EGCG), and fish, egg yolk, cod liver oil (Vitamin D). Regarding Vitamin D it should be considered that this hormone is produced to more than 80% by our body after sun exposure of the skin. The importance of sufficient Vitamin D levels in the body has been underlined by a recent study which clearly demonstrates that sufficient plasma levels of 25-hydroxyvitamin D >75 nmol/L were associated with a lower risk for pancreatic cancer among participants in five large prospective cohorts. The actual available data reveal that a frequent intake of vegetables of the cruciferous family along with a colourful selection of many other fruits and vegetables combined with sufficient sun exposure may lower the cancer risk and prolong life of cancer patients.
Please also note the recommendations below for nutrition and life-style for prevention and treatment of cancer:
- Be as lean as possible without becoming underweight
- Be physically active for at least 30 minutes every day
- Avoid sugary drinks. Limit consumption of energy-dense foods
- Eat more of a variety of vegetables, fruits, whole grains and legumes such as beans
- Limit consumption of red meats (such as beef, pork and lamb) and avoid processed meats
- If consumed at all, limit alcoholic drinks to 2 for men and 1 for women a day
- Limit consumption of salty foods and foods processed with salt
- Don’t use supplements to protect against cancer
- *It is best for mothers to breastfeed exclusively for up to 6 months and then add other liquids and foods
- *After treatment, cancer survivors should follow the recommendations for cancer prevention
* Special Population Recommendations
And always remember – do not smoke or chew tobacco.
Leading organizations (WCRF/AICR) recommend not to use dietary supplements to protect against cancer. In fact nutrition and general habits should be changed for good. A healthy lifestyle provides sufficient levels of secondary plant substances i.e. sulforaphane to your body. Freeze-dried broccoli sprouts recommended above may still be taken additionally. It is a healthy food that contains lots of fibers and which is rich of sulforaphane. However, if you eat cruciferous vegetables like cress, radish, mustard, cabbage on a regular basis and use canola oil, it will presumably have the same positive effect.
General Adjustment of Diet and Lifestyle is important
Broccoli and its sprouts alone are certainly not a panacea, which is taken like a headache tablet and then all will be well again. For a broad scale intake of many bioactive agents to fight tumor stem cells a balanced, mostly plant-based diet with a high content in raw food is important. Daily outdoor exercise for at least 30 min are important for sufficient vitamin D levels, for a healthy stress-balance and good mood.