I posted about this elsewhere but I thought it deserved its own thread, since to-date I don't see one for this organic sulfur compound. I first heard about it through Dr Rhonda Patrick's various podcasts and interviews, on her website and elsewhere. She has several videos about this compound, and how a lot of the beneficial effects of cruciferous vegetables (such as reduced all-cause mortality, including cancers) come from sulforaphane and other constituent organosulfurs. A comprehensive list of the benefits of sulforaphane can be found here:
39 Sulforaphane Benefits, Foods, Supplements + Broccoli Sprouts - Selfhacked
Sulforaphane Negatives
On optimizing sulforaphane bioavailability:
The rest of the article covers the more nuts-and-bolts aspects of sulforaphane's effects in terms of protein and gene regulation effects.
Rhonda Patrick's most comprehensive video on sulforaphane can be found here. The information is much more digestible:
39 Sulforaphane Benefits, Foods, Supplements + Broccoli Sprouts - Selfhacked
Much of the information given below is derived from animal- and laboratory-based studies. Human studies are falling behind, but will hopefully soon follow.
1) Sulforaphane Promotes Detoxification
Sulforaphane is an indirect antioxidant. It boosts the antioxidant capacity of cells by at least 2 mechanisms [R]:
Inducing phase 2 detoxification enzymes – Sulforaphane is the most potent inducer of phase 2 enzymes identified to date. It acts by activating Nrf2 and ARE, and increasing glutathione S-transferase activity [R, R, R, R]
Increasing cellular glutathione levels
2) Sulforaphane Prevents and Combats Cancer
Of all the molecules I’ve studied, sulforaphane and broccoli sprouts are the most promising at preventing and killing cancer.
A diet rich in Brassica vegetables decreases the risk of cancer [R, R].
Three to five servings per week are sufficient to decrease the risk of cancer by ∼30% to 40% [R].
Subjects who consumed at least one portion of cruciferous vegetables per week had a significantly reduced risk of oral cavity, pharynx, esophageal, colorectal, breast, and kidney cancers [R].
The great thing about sulforaphane is that it kills cancer cells, but seems to have very little effect on healthy cells [R].
Sulforaphane treatment reduced DNA damage and mutation rate when cancer-causing chemicals bound to DNA [R].
Sulforaphane kills colorectal cancer cells, oral squamous cell carcinoma cells, breast cancer cells, cervical cancer cells, liver cancer cells, prostate cancer cells, and leukemia cells [R, R, R, R].
SFN inhibited the growth of glioblastoma, thyroid, prostate, mammary, tongue, and lung cancer in animals [R, R, R, R, R, R].
Broccoli sprouts significantly and dose-dependently inhibited bladder cancer development in rats, and UV-radiation-induced skin cancer development in mice [R, R].
Sulforaphane combats cancer by multiple mechanisms:
SFN inhibits phase I enzymes that can activate pro-carcinogens [R]
SFN induces phase II enzymes that are responsible for eliminating chemicals that damage DNA [R]
SFN changes gene activation/deactivation, and causes demethylation, thereby restoring the activity of important tumor-suppressing and cell-cycle controlling genes [R, R]
Sulforaphane induces cancer cell death [R]
Sulforaphane inhibits the NF-κB pathway, thus reducing inflammation [R]
Sulforaphane induces cell cycle arrest, and thereby inhibits cancer cell proliferation [R]
Apart from being effective in its own right, sulforaphane also enhances the efficacy of anti-cancer drugs including cisplatin, gemcitabine, doxorubicin, and 5-fluorouracil, toward pancreatic and prostate cancer cells, while limiting their toxicity to normal cells [R].
However, although sulforaphane was found to be safe and effective in several studies, it was not effective in 2 clinical trials [R, R].
3) Sulforaphane Lowers Cholesterol
Eating glucoraphanin-rich broccoli significantly reduced LDL cholesterol in humans [R].
SFN is produced in the body from glucoraphanin.
In 12 healthy subjects, eating fresh broccoli sprouts (100 g/day) for 1 week decreased total and LDL cholesterol, and increased HDL cholesterol. Broccoli sprouts also improved oxidative stress markers [R].
4) Sulforaphane Prevents and Combats Heart & Cardiovascular Disease
A diet rich in Brassica vegetables decreases the risk of cardiovascular disease [R].
Both sulforaphane and broccoli sprouts high in glucoraphanin decreased blood pressure in hypertensive rats [R, R].
A short dietary treatment of rats with broccoli sprouts protected the heart against oxidative stress and cell death caused by ischemia (reduced blood flow and low oxygen) [R].
Sulforaphane also reduced heart damage after infarct in rats [R].
Sulforaphane protected against the hardening of the arteries (atherosclerosis), and suppressed inflammation in hardened arteries in animals [R, R].
SFN further possesses antithrombotic activities. SFN inhibited human platelet aggregation and reduced blood clot formation [R].
SFN reduced the mortality of acute lung thromboembolism in mice [R].
Finally, sulforaphane is beneficial in stroke. In rodents, SFN decreased brain infarct (damaged tissue from stroke) volume, and maintained the blood-brain barrier (BBB) integrity and neurological function after stroke [R, R].
5) Sulforaphane May Combat Obesity
In mice with Western diet-induced obesity, 3 weeks of sulforaphane supplementation reduced weight gain, leptin and insulin levels, and improved insulin resistance, glucose tolerance, and cholesterol [R].
Similarly, in another study, sulforaphan inhibited high-fat-diet-induced obesity and fat accumulation in mice. It also reduced total cholesterol, leptin, and liver triglyceride levels [R].
6) Sulforaphane Improves Diabetes
Broccoli sprouts improve many parameters in diabetes. In type 2 diabetics, eating broccoli sprouts increased blood antioxidant capacity and HDL cholesterol, and decreased oxidative stress, triglycerides, insulin, insulin resistance, and CRP [R, R, R].
Sulforaphane also prevented diabetes-related complications in animals, such as [R, R]:
Nephropathy
Tissue damage
Vascular complications
Diabetes-induced heart dysfunction
Thickening of the heart muscle
Heart damage in mice
However, in rats, while SFN had positive effects on diabetes, liver function and cholesterol were aggravated after treatment [R].
7) Sulforaphane Can Boost the Immune System
Sulforaphane enhanced bacterial clearance by macrophages and increased the activity of natural killer cells (NK cells) in mice [R].
In studies with aging mice, sulforaphane boosted Th1 immunity and restored or delayed the decline of cellular immunity that happens with aging [R].
8) Sulforaphane Is Antiviral
Broccoli sprouts enhanced human antiviral responses [R].
Broccoli sprouts reduced influenza viral load in humans [R].
SFN exhibited significant antiviral activity against influenza (the flu), HIV, Epstein-Barr virus, and the hepatitis C virus [R, R].
SFN blocked HIV infection in macrophages. Macrophages play a critical role in HIV infection, forming long-lived viral reservoirs and distributing the virus in the body [R].
On the other hand, SFN may exacerbate infections by viruses that hijack Nrf2, such as the Marburg virus, the Kaposi’s sarcoma-associated herpesvirus (KSHV), and Dengue virus [R].
9) Sulforaphane Combats Bacterial and Fungal Infections
In one study, 23 out of 28 tested bacterial and fungal species were inhibited by sulforaphane [R].
Mycobacterium abscessus is frequently found in patients with cystic fibrosis and in immunosuppressed patients. Pretreatment of macrophages with sulforaphane significantly decreased bacterial burden [R].
Human β-defensin-2 (HBD-2) plays an important role against bacterial invasion. Sulforaphane is able to increase antimicrobial peptides such as HBD-2 [R].
10) Sulforaphane Protects the Skin
Sulforaphane provides protection against UVA and UVB inflammation, sunburn, and skin damage [R, R].
UV radiation induces direct DNA damage and inflammation, and suppresses the immune response. Sulforaphane-rich extracts of 3-day-old broccoli sprouts increased phase 2 enzymes in human and mouse skin, protected against UV radiation-induced inflammation and edema in mice, and reduced susceptibility to erythema (skin redness) in humans [R].
Sulforaphane protected skin cells against oxidative stress caused by UVA radiation with a ∼50% reduction in reactive oxygen species (ROS) [R].
UVA irradiation plays a role in the premature aging of the skin by triggering oxidative stress, and inducing collagen degradation, a hallmark of photoaged skin. Pretreatment of mouse skin with sulforaphane protected against UVA-mediated collagen depletion [R].
Sulforaphane improved skin blistering in epidermolysis bullosa simplex [R].
Epidermolysis bullosa simplex (EBS) is a rare inherited condition in which the skin loses its integrity after mechanical trauma.
11) Sulforaphane Combats Inflammation
Sulforaphane inactivated nuclear factor kappa-B (NF-κB), a key inducer of inflammation [R].
Sulforaphane also activated Nrf2, which lowered inflammation and decreased proinflammatory mediators in mice [R, R].
12) Sulforaphane May Combat Depression and Anxiety
Inflammation has been recognized as one of the causes of depression. By reducing inflammation, sulforaphane can help combat depression.
Repeated SFN administration reversed depression- and anxiety-like behaviors in chronically stressed mice, likely by inhibiting the hypothalamic-pituitary-adrenal (HPA) axis and inflammatory responses to stress [R, R].
In another study, Nrf2 deficiency in mice resulted in depressive-like behavior, while the induction of Nrf2 by sulforaphane had antidepressant-like effects [R].
Also, dietary intake of glucoraphanin during the juvenile and adolescent periods in mice prevented the onset of depression-like behaviors at adulthood [R].
13) Sulforaphane Protects the Brain and Restores Cognitive Function
Sulforaphane increased neuronal BDNF in mice, a factor that supports the survival of existing neurons and encourages the formation of new neurons and synapses [R].
SFN reduced brain inflammation in various animal models of pathogen-induced neuroinflammation and neurodegenerative disease [R, R, R, R].
Sulforaphane promoted microglia differentiation from pro-inflammatory M1 to anti-inflammatory M2 state. This reduced brain inflammation and restored spatial learning and coordination in rats [R].
Sulforaphane is beneficial in various pathological conditions, as it:
Improved cognitive performance and reduced working memory dysfunction in rats after traumatic brain injury [R]
Weakened cognitive deficits in mouse models of psychiatric disease. Also, the intake of glucoraphanin during the juvenile and adolescent periods prevented the onset of cognitive deficits at adulthood [R]
Alleviated brain swelling in rats, by attenuating the blood-brain barrier disruption, decreasing the levels of pro-inflammatory cytokines, and inhibiting NF-κB; it also increased AQP4 (a water channel protein) levels, thereby reducing brain swelling [R, R]
Prevented memory impairment and increased the survival of hippocampal neurons in diabetic rats [R]
Sulforaphane recovered memory in mice and rats with chemically induced memory impairment [R, R, R].
SFN exerted positive effects against brain damage induced by acute CO poisoning in rats [R].
Sulforaphane protected human neurons against prion-mediated neurotoxicity [R].
Insufficient NRF2 activation in humans has been linked to neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis [R].
SFN, as a potent Nrf2 activator, may help in the treatment of these diseases.
14) Sulforaphane May Help with Parkinson’s Disease
Parkinson’s disease is characterized by selective loss of dopaminergic neurons in the substantia nigra of the brain. In animal models of Parkinson’s disease, sulforaphane improved deficits in motor coordination and inhibited dopaminergic neuronal loss [R, R, R, R].
15) Sulforaphane May Help with Alzheimer’s Disease
Abnormal production and aggregation of amyloid beta (Aβ) peptide are major factors implicated in the pathogenesis of Alzheimer’s disease (AD). Broccoli sprouts protected against Aβ-induced cell death, and sulforaphane inhibited Aβ-related inflammation [R, R, R].
Sulforaphane reduced Aβ plaque and neuron loss, and improved cognitive impairment in Alzheimer’s disease-like mouse models [R, R, R].
16) Sulforaphane May Help with Huntington’s Disease
Sulforaphane activated the protein degradation machinery that promotes huntingtin degradation and reduced huntingtin toxicity in mice [R].
17) Sulforaphane May Prevent Seizures
Sulforaphane protected against seizures and elevated the seizure thresholds in mice [R].
18) Sulforaphane Improves Schizophrenia
Sulforaphane improved performance in a learning task in outpatients with schizophrenia [R].
Methamphetamine can induce psychosis in susceptible people. Sulforaphane weakened behavioral abnormalities in mice after administration of methamphetamine or phencyclidine, suggesting that it may help with schizophrenia [R].
Sulforaphane protected against antipsychotic-induced toxicity in dopaminergic neurons [R].
19) Sulforaphane May Be Beneficial for Substance Abuse
Sulforaphane weakened behavioral and neuropathological changes associated with methamphetamine exposure in mice. Pretreatment with sulforaphane weakened acute hyperlocomotion (increase in movement) in mice after a single administration of methamphetamine [R].
Also, the development of behavioral sensitization after repeated administrations of methamphetamine was significantly reduced by pretreatment with sulforaphane [R].
20) Sulforaphane May Improve Autism Symptoms
In a clinical trial, sulforaphane improved behavior in young men with autism [R].
Sulforaphane activates genes that protect cells against oxidative stress, inflammation, and DNA-damage, all of which are associated with autism spectrum disorder [R].
21) Sulforaphane Can Protect Against GI Injury and Inflammation
SFN protects the gut against NSAID-related damage. SFN improved aspirin/NSAID-induced injury of the gut in mice, and inhibited gastric ulcers in rats [R, R, R].
Nrf2-deficient mice exhibit worse colitis symptoms, indicating that SFN can help in this condition by activating Nrf2 [R].
Indeed, in another study, treatment with SFN decreased inflammation in mice with colitis [R].
22) Sulforaphane Combats H. pylori
SFN is beneficial against Helicobacter pylori infections [R].
Broccoli sprouts inhibit the growth of H. pylori [R].
In several human studies, broccoli sprouts decreased H. pylori colonization and reduced stomach inflammation [R, R, R].
These effects were temporary, because values went back to their original levels 2 months after treatment was discontinued [R].
In another study, broccoli sprout extract did not inhibit H. pylori colonization, but nevertheless protected the stomach lining [R].
In H. pylori-infected type 2 diabetic patients, broccoli sprout powder, in addition to standard triple therapy, considerably improved H. pylori eradication, and also improved heart health in these subjects [R].
H. pylori increases oxidative stress, thereby causing damage to the stomach lining, slowing down damage repair, and eventually inducing gastric cancer. Sulforaphane activates Nrf2-dependent antioxidant enzyme activities, thereby protecting stomach cells from oxidative injury [R]. Sulforaphane can also protect the stomach lining by reducing inflammation [R]. Improved stomach lining health also makes it more difficult for H. pylori to colonize the stomach, which explains the reduced rate of colonization found in some human studies [R].
23) Sulforaphane Improves Liver Function
In men with fatty liver, broccoli sprouts improved liver function and decreased ALT, γ-GTP, and ALP [R]. In animals, SFN protected against a wide variety of liver diseases caused by toxic chemicals, drugs, alcohol, and high-calorie diets [R, R, R]. Broccoli sprouts activated detoxification and glutathione production, increasing GST while decreasing AST and ALT in rat livers [R]. Sulforaphane inhibited alcohol-induced fatty liver in mice [R]. Many drugs, including sodium valproate, cause liver toxicity. In rats, SFN significantly boosted liver function, reduced ALT, AST, and ALP, and improved valproate-induced liver damage [R].
24) Sulforaphane Reduces Health Damage from Pollution
Sulforaphane helped the body detoxify airborne pollutants, pesticides, and heavy metals by activating detoxification systems, mainly the phase II enzymes. In a farming community exposed to airborne pollutant with a high risk of hepatocellular carcinoma, broccoli sprouts enhanced the detoxification of airborne pollutants and reduced the risks of cancer [R].
Sulforaphane induced phase II enzymes in the upper airway of human subjects [R].
Phase II enzymes have important protective effects against diesel exhaust particles (DEP), ozone, and tobacco smoke [R].
Sulforaphane reduced the pro-inflammatory and pro-allergic effects typically caused by exposure to diesel exhaust particle [R]. Sulforaphane protected human white blood cells (lymphocytes) from pesticide-induced DNA damage [R].
Aflatoxin binds DNA and causes liver cancer. Sulforaphane reduced the binding of aflatoxin to DNA in rats [R].
Sulforaphane inhibited the mutagenicity caused by heterocyclic amines (cooked food mutagens) [R].
Cadmium reduced testosterone, sperm motility, sperm count, and increased sperm deformity in mice. SFN improved sperm quality, testosterone, and antioxidant levels [R].
Sulforaphane lessened liver damage caused by cadmium selenide in mice [R]. Exposure to arsenic increases the risk of lung disease. Sulforaphane blocked DNA damage and mild lung damage caused by 2-week exposure of mice to arsenic-containing dust [R].
25) Sulforaphane May Be Beneficial for Airway Inflammation and Asthma.
Sulforaphane has had beneficial effects in animals with asthma and airway inflammation, but studies in humans are less conclusive [R].
Broccoli sprout extract suppressed airway inflammation in humans exposed to diesel exhaust particles (equivalent to daily PM exposure levels on a Los Angeles freeway) [R].
Sulforaphane also improved airway and lung constrictions caused by methacholine in 60% of moderate asthmatics. However, in 20% of the asthmatics, sulforaphane worsened the constrictions [R].
In other human trials, broccoli sprouts did not improve asthma, COPD symptoms, or ozone-induced airway inflammation [R, R, R].
Patients with chronic obstructive pulmonary disease (COPD) have innate immune dysfunction in the lung, resulting in frequent bacterial infections. Sulforaphane restored bacteria recognition and phagocytosis in lung macrophages from COPD patients [R].
Sulforaphane enhanced bacterial clearance by lung macrophages and reduced inflammation in mice exposed to cigarette smoke for 6 months [R].
26) Sulforaphane Combats Autoimmune Inflammation.
SFN can be beneficial against T-cell driven autoimmune disorders, such as multiple sclerosis-like diseases in animals, but studies in humans are still lagging. Sulforaphane significantly inhibited the development and severity of MS-like disease in mice, mitigating inflammatory infiltration and demyelination in the spinal cord [R, R]. Sulforaphane caused improvement by silencing Th17/Th1 responses within the brain/neurons [R]. NRF2-deficient mice have exacerbated pathology in this model [R]. Sulforaphane activated the Nrf2/ARE pathway, which helps combat the disease [R].
27) Sulforaphane Can Reduce Pain.
Broccoli sprout extract reduced pain in mice and rats in a dose-dependent manner, possibly by activating the opioid receptors [R]. In mice, sulforaphane lessened pain, reduced pro-inflammatory cytokines, and increased anti-inflammatory cytokines. Sulforaphane blocked COX2 and iNOS in injured nerve cells, the 2 key enzymes implicated in inflammation and neuropathic pain [R].
28) Sulforaphane Can Promote Bone Formation.
In females, low levels of estrogen, such as during menopause or after an ovary removal surgery, can lead to reduced bone mass (osteoporosis). Sulforaphane promoted bone formation and increased bone volume (∼20%) in both normal mice and mice without ovaries. Sulforaphane diminished bone resorption, thereby shifting the balance to a state favoring bone acquisition [R].
29) Sulforaphane Can Be Beneficial for Arthritis.
A sulforaphane-rich diet improved osteoarthritis in mice. Sulforaphane inhibited key metalloproteinases implicated in osteoarthritis, independently of Nrf2, and blocked inflammation through NF-κB to protect against cartilage destruction [R].
Some of the SFN effects may be mediated by Nrf2, because enhanced oxidative stress and cartilage damage were observed in Nrf2-deficient mice with arthritis [R].
SFN reduced the severity of arthritis in mice by decreasing pro-inflammatory cytokines [R].
Several inflammatory autoimmune diseases, such as rheumatoid arthritis and osteoarthritis, switch the polarization of monocytes into classically activated pro-inflammatory macrophages (M1 type). Sulforaphane blocked the inflammatory responses specific to M1 macrophages (Th1) and shifted macrophage production to M2 macrophages [R]. M2 (Th2) decrease inflammation and encourage tissue repair.
30) Sulforaphane Can Prevent Muscle Damage.
Sulforaphane prevented muscle damage in rats after acute bouts of exhaustive exercise, by acting as an indirect antioxidant in the muscle [R].
31) Sulforaphane May Be Beneficial for Muscular Dystrophy.
Sulforaphane reduced dystrophic muscle damage and muscle inflammation in mice by inducing Nrf2 [R, R]. In mouse models of Duchenne muscular dystrophy, sulforaphane significantly increased muscle mass, muscle force (∼30%), and running distance. Sulforaphane also reduced muscle hypertrophy, heart muscle hypertrophy, and inflammation [R].
32) Sulforaphane Can Protect the Kidneys.
SFN protected against kidney damage in animals [R, R]. Chemotherapeutics, such as cisplatin, can be toxic to kidneys. In animals, sulforaphane prevented inflammation and kidney damage caused by cisplatin [R].
33) Sulforaphane Can Support Hair Growth Dihydrotestosterone (DHT) causes androgenic baldness.
Sulforaphane increased the production of enzymes that degrade DHT [R]. SNF significantly enhanced hair regeneration in mice, and reduced testosterone and DHT levels in the blood [R]. SFN increased the amount of testosterone degrading enzymes, such as 3α-HSD, in the liver, accelerated the degradation of blood DHT, and reversed the suppression of hair growth by DHT [R].
34) Sulforaphane Can Increase Alcohol Tolerance
37) Sulforaphane May Be Beneficial Against Keloids. Sulforaphane inhibited cell growth and reduces collagen in keloid cells [R].
38) Sulforaphane May Improve Bladder Dysfunction. In rats with bladder outlet obstruction, SFN treatment increased bladder capacity and bladder compliance [R].
39) Sulforaphane May Benefit Children with HGPS. Hutchinson-Gilford progeria syndrome (HGPS) is a rare childhood premature aging disorder linked to mutations in the LMNA gene. Protein clearance and autophagy are impaired in HGPS cells. SFN stimulated protein clearance by autophagy and reversed cellular phenotypic changes, both of which are the hallmarks of HGPS [R].
Sulforaphane Negatives
1) Sulforaphane May Transiently Decrease Genome Stability
Sulforaphane increases the activation of many beneficial genes, including tumor suppressor genes. However, sulforaphane also activates long terminal repeats (LTRs), DNA sequences found within our genome that impair genome stability and cause mutations [R].
Consumption of broccoli sprouts by human volunteers caused a 10-fold increase in LTR activation in white blood cells. These effects are transient, and it remains to be determined whether they are biologically meaningful [R].
Other studies on human volunteers recorded no abnormal events related to broccoli sprout consumption [R].
Genotoxic effects were observed in unpublished studies with pigs fed with 600 g of raw broccoli for 12 days. These pigs had an increase in DNA strand breaks by 21% in the colon [R].
Also, after feeding raw or steamed broccoli to mice and rats, an increase in DNA adducts (cancer-causing chemicals binding to DNA) was observed [R].
However, all these effects in animals were observed for mature broccoli plant consumption. An additional benefit of broccoli sprouts is that they contain negligible quantities of indole glucosinolates, which predominate in the mature vegetable, and may give rise to degradation products (e.g., indole-3-carbinol). This can enhance tumorigenesis [R].
2) Excessive Consumption May or May Not Cause Liver Toxicity
There is a single case report of liver toxicity after drinking large amounts of broccoli juice for 4 weeks (800 ml/day). Transaminases, aspartate aminotransferase, and c-glutamyltrans-peptidase were elevated, but decreased to normal within 15 days [R].
This was also caused by consuming the mature plant and may be caused by other substances found in the broccoli plant, unrelated to sulforaphane.
On optimizing sulforaphane bioavailability:
Broccoli Sprouts Are the Richest Source of Sulforaphane. The amount of sulforaphane (glucoraphanin) can vary widely in vegetables [R]. Broccoli is not the only cruciferous vegetable which has SFN, but it yields the highest amounts, with glucoraphanin content around 75% of total glucosinolates [R]. Furthermore, 3-day-old broccoli sprouts contain 10 to 100 times higher levels of glucoraphanin than does a mature broccoli [R, R].
Myrosinase Is Necessary for Sulforaphane Production. The majority of SFN is formed when glucoraphanin gets processed by myrosinase, upon plant tissue damage (e.g. chopping, chewing). When plant myrosinase is inactive or absent, a small amount of SFN may still be formed by gut bacteria-derived myrosinase activity [R].
Gut bacteria, such as Bifidobacterium, Lactobacillus, and Bacteroides, have been reported to possess myrosinase-like activity [R].
Many available broccoli sprout supplements are myrosinase-inactive [R, R]. SFN absorption was sevenfold lower for glucoraphanin supplements than equivalent glucoraphanin-containing fresh broccoli sprouts with the active enzyme [R]. SFN absorption from a glucoraphanin powder devoid of myrosinase activity improved when consumed along with an active source of myrosinase (such as air-dried broccoli sprouts) [R].
Also, combining broccoli sprouts with the broccoli powder enhanced SFN absorption from the broccoli powder [R].
Processing Inactivates Myrosinase. The bioavailability of sulforaphane from fresh broccoli is much higher than that from cooked broccoli [R]. Higher amounts of sulforaphane were found in the blood and urine when broccoli was eaten raw (bioavailability of 37%) versus cooked (3.4%) [R]. Cooking and/or blanching (during freezing process) of cruciferous vegetables inactivates myrosinase and decreases sulforaphane bioavailability [R]. Boiling for more than 1 minute, or steaming for more than 4 to 5 minutes, inactivates myrosinase [R].
Myrosinase Enhancers. Mustard seeds contain a more resilient form of myrosinase. The addition of powdered mustard seeds to heat-processed broccoli significantly increased the production of sulforaphane [R].
Avoiding Nitrile Formation. Broccoli also contains significant amounts of epithiospecifier protein (ESP), an inhibitor of myrosinase. ESP produces inactive sulforaphane nitrile. Under certain conditions, as much as 75% nitrile is created [R]. ESP is more heat sensitive than myrosinase. Steaming for 1 to 3 minutes provides less nitrile and more sulforaphane yield from a broccoli meal [R].
Sulforaphane Metabolism. Sulforaphane is rapidly absorbed, peaking in the blood as early as 1 to 3 hours after ingestion [R, R]. Once SFN is distributed, there is evidence that it can accumulate in tissues and produce anticancer blocking and suppressing effects [R]. In the blood, sulforaphane-glutathione accounts for more than 50% of total sulforaphane metabolites [R]. SFN and its metabolites are cleared from the body within 12 to 72 hours of dosing, by urinary excretion [R, R, R]. Maintenance of SFN concentrations in the body can be achieved by consuming recommended servings of cruciferous vegetables once a day [R].
The rest of the article covers the more nuts-and-bolts aspects of sulforaphane's effects in terms of protein and gene regulation effects.
Rhonda Patrick's most comprehensive video on sulforaphane can be found here. The information is much more digestible:
