Sulforaphane is a natural compound found in cruciferous vegetables (broccoli, cabbage, cauliflower, Brussels sprouts and kale) that is reported to have potent antioxidant and possible anti-inflammatory actions.
Sulforaphane belongs to a group of disease-fighting compounds in plant foods, known as the isothiocyanates, and is found in highest concentrations in broccoli and broccoli sprouts.
In vitro studies suggest that it has anticancer effects against prostate, breast and urinary cancers. It may also protect the skin from ultraviolet radiation (1).
Preliminary studies to further evaluate these effects are currently being conducted in humans.
Sulforaphane may help treat certain cancers. Research suggests that cruciferous vegetables are not only an important source of nutrients, but perhaps a key to eliminating cancer as a life-threatening disease.
This compound has been shown to block the initiation stage in carcinogenesis by inhibiting enzymes that convert procarcinogens to carcinogens, and inducing phase 2 enzymes that metabolize carcinogens to facilitate excretion (2).
Isothiocyanates are a well-known class of cancer chemopreventive agents, and since broccoli is a rich source of several isothiocyanates, researchers are testing their ability to inhibit cancer.
In a 2010 in vitro study, it was determined that sulforaphane eliminated breast cancer cells in vivo, thereby repressing tumor growth after the reimplantation of primary tumor cells into the secondary mice (3).
According to Cancer Research journal, dietary administration to rats of a freeze-dried aqueous extract of broccoli sprouts significantly and dose-dependently inhibited bladder cancer. The incidence, multiplicity, size and progression of bladder cancer were all inhibited by the extract.
In addition, inhibition of bladder carcinogenesis by the extract was associated with significant induction of enzymes in the bladder (glutathione S-transferase and NAD(P)H:quinone oxidoreductase 1), that are important protectants against oxidants and carcinogens (4).
An additional benefit of sulforaphane is that it appears to kill cancer cells, while sparing healthy cells (5).
Sulforaphane has the potential as a unique supplement for management of type 2 diabetes and its complications. In hyperglycemic and oxidative conditions, sulforaphane has the potential to activate the Nrf2-dependent antioxidant response-signaling pathway, induces phase 2 enzymes (major detoxification enzymes), attenuates oxidative stress, and inactivates nuclear factor kappa-B (NF-κB), a key modulator of inflammatory pathways.
Supplementation with high sulforaphane content broccoli sprouts by type 2 diabetics results in increased total antioxidant capacity of plasma and a decrease in oxidative stress index, lipid peroxidation, serum triglycerides, oxidized low-density lipoprotein (LDL)/LDL-cholesterol ratio, serum insulin and insulin resistance (6).
Sulforaphane protects the skin against UV radiation. Significant increases in the incidence of skin cancers are largely attributable to higher exposure of an aging population to UV radiation. UV radiation causes a chain reaction of harmful events, including direct DNA damage, generation of reactive oxidants that peroxidize lipids and damage other cellular components, initiation of inflammation, and suppression of the immune response.
One study found that topical application of sulforaphane-rich extracts of 3-day-old broccoli sprouts protected against UV radiation-induced inflammation and edema in mice.
In humans, it reduced susceptibility to sunburn (7).
Sulforaphane helps fight H. pylori bacteria. H. pylori is a type of bacteria that causes infection in the stomach. It is the main cause of peptic ulcers, and it can also cause gastritis and stomach cancer (8).
In one study, 48 H. pylori-infected patients were randomly assigned to feeding of broccoli sprouts for 8 weeks or to consumption of an equal weight of alfalfa sprouts (not containing sulforaphane) as placebo.
Intervention with broccoli sprouts, but not with placebo, decreased the levels of urease and H. pylori stool antigen (both biomarkers of H. pylori colonization) and serum pepsinogens I and II (biomarkers of gastric inflammation).
This treatment seems to enhance chemoprotection of the gastric mucosa against H. pylori-induced oxidative stress (9).
A growing number of studies also show this compound’s ability to inhibit the growth of a broader range of bacterial and fungal pathogens, including those that may develop resistance to conventional antibiotics (10).
Sulforaphane may help fight certain strains of the influenza virus. In a recent randomized, double-blinded, placebo-controlled study, researchers found that sulforaphane-containing broccoli sprouts enhanced the antiviral response against an influenza virus strain (11).
Sulforaphane may help treat kidney disease. In 2012, researchers set out to investigate whether sulforaphane can prevent the progression of diabetic kidney disease in a type 1 diabetic mouse model.
Diabetic mice were given sulforaphane at 0.5 mg/kg body weight daily for 3 months. At the end of 3-month of treatment, diabetic kidney disease (shown by renal inflammation, oxidative damage, fibrosis and dysfunction), was significantly prevented.
Researchers noted that continual use of sulforaphane is necessary to maintain this effect (12).
Sulforaphane may improve bladder dysfunction. In a study published in a 2016 issue of Oxidative Medicine and Cellular Longevity, researchers evaluated the effects of sulforaphane on bladder dysfunction in rats caused by bladder outlet obstruction — a blockage at the base of the bladder that reduces or stops the flow of urine (13,14).
This condition is common in aging men.
It is believed that this compound has significant protective effects against oxidative stress and could treat bladder dysfunction through activation of the Nrf2-ARE pathway (a powerful defense system that contributes to an array of antioxidant, detoxification and cell survival genes) in the bladder of rats with bladder outlet obstruction.
Sulforaphane is safe when used in the amounts found in broccoli, broccoli sprouts and other cruciferous vegetables.
There is not enough information available to know if it is safe to take by mouth as a supplement (15).
The optimal supplemental dose of sulforaphane is unknown. Low quantities are likely attainable via consumption of broccoli or cruciferous vegetable products. While higher doses may be beneficial, future research will provide a better understanding of the recommended dosage.
Sulforaphane is a natural compound found in cruciferous vegetables, most notably broccoli and broccoli sprouts. It belongs to a group of disease-fighting compounds in plant foods, known as the isothiocyanates and has antioxidant and anti-inflammatory actions.
Studies show its potential to fight certain types of cancer, manage type 2 diabetes, shield the skin against UV radiation and protect against viral and bacterial infections.
Sulforaphane is safe when used in the amounts found in cruciferous vegetables. The recommended dosage and safety of supplementation warrants further clinical evaluation.