IngredientsGlucoraphanin is a glucosinolate found in broccoli, mustard, and other cruciferous vegetables. It is a naturally occurring glucosinolate and a stable precursor of the Nrf2 inducer sulforaphane, which possesses antioxidant, anti-inflammatory, and anti-carcinogenic effects. The compound's Chemical Abstracts Service (CAS) registry number is CAS No. 21414-41-5.
Glucosinolates consist of a sugar moiety, an isothiocyanate, and a sulfate group, as well as a variable group, R, which may be aromatic or aliphatic in nature. Glucoraphanin is derived from dihomomethionine, which is methionine chain-elongated twice. The sulfinyl group is chiral, and has R absolute configuration. The stereochemistry is set when an oxygen atom is added to 4-methylthiobutylglucosinolate by a flavin monooxygenase.
Glucoraphanin from broccoli and its sprouts and seeds is a water-soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. It belongs to a group of plant compounds called glucosinolates. Glucosinolates are compounds that contain a sulfur group and are typically described as pungent; they have strong flavors and smells.
Glucoraphanin is the major glucosinolate in broccoli. Glucoraphanin occurs in all tissues of broccoli plants, though it is most abundant in the aerial portions and the developing florets (flower buds) and ultimately the seeds, are richest in this compound. Although two or three other edible cruciferous (Brassica) species contain significant amounts of glucoraphanin, it is not as widespread as popular culture would have it.
Sulforaphane's precursor glucoraphanin is abundant in broccoli, cauliflower, and cabbage, with the highest concentration being found in broccoli sprouts. Glucoraphanin is especially concentrated in seeds and young sprouts. Three-day-old sprouts are often cited as having the highest levels per gram. As the plant matures into a full head of broccoli, glucoraphanin levels generally decrease.
Crucifer seeds are a likely source for obtaining glucoraphanin, owing to a higher concentration of glucoraphanin and the relative ease of processing seeds as compared to vegetative parts. The amount varies tremendously from one broccoli plant to another with no way for consumers to tell how much glucoraphanin is in the broccoli they buy.
Three high-glucoraphanin F₁ broccoli hybrids were developed in independent programs through genome introgression from the wild species Brassica villosa. Two high-glucoraphanin hybrids have been commercialized as Beneforté® broccoli. The study illustrates the translation of research on glucosinolate genetics from Arabidopsis to broccoli, the use of wild Brassica species to develop cultivars with potential consumer benefits, and the development of cultivars with contrasting concentrations of glucoraphanin for use in blinded human intervention studies.
Brassica species are widely used in traditional medicine, human food, and animal feed. Historically, populations consuming diets rich in cruciferous vegetables have been associated with reduced risks of chronic diseases, particularly certain cancers and cardiovascular ailments. This epidemiological evidence has spurred scientific interest in the bioactive constituents of these vegetables, with glucoraphanin and its metabolite sulforaphane remaining key focal points.
Epidemiological studies have associated diets rich in cruciferous vegetables such as heading broccoli or calabrese (Brassica oleracea L. var italica Plenck) with reduced incidence of myocardial infarction, cardiovascular-related mortality, and reduced incidence or progression of various cancers, including lung, bowel, kidney, breast, and prostate. Significant levels of protection are most frequently observed in people that consume several portions per week, which is typical of traditional diets in parts of Asia, but is atypical of western diets.
The name "glucoraphanin" was initially coined for an antibacterial compound isolated from radish. Today, it is primarily associated with the Brassica family and has been extensively studied since the 1940s for its health-promoting properties.
It is important to note that glucoraphanin as an isolated compound was not itself the subject of traditional use. Traditional cultures used whole cruciferous plants in culinary and medicinal contexts; glucoraphanin is a modern phytochemical identification that helps explain the biological basis of longstanding dietary patterns associated with these plants. In 1992, Dr. Paul Talalay, MD, and colleagues at Johns Hopkins School of Medicine identified sulforaphane as the most potent natural inducer of Phase 2 detoxification enzymes. Since 1992, glucoraphanin and its bioactive form sulforaphane have been extensively studied at Johns Hopkins and other medical institutions around the world, with more than 1,700 studies published which support the possible health benefits of these compounds.
In addition to the traditional avenue for obtaining sulforaphane — namely, the consumption of appropriate cruciferous vegetables — other consumer products containing added glucoraphanin, the natural precursor to sulforaphane, are now appearing. Available preparations include:
A practical advantage of glucoraphanin is its stability. Pure sulforaphane is reactive and degrades with heat and time; glucoraphanin is comparatively stable in capsules or powders. When combined with active myrosinase — either built into the product or added via food — glucoraphanin can deliver robust sulforaphane exposure without the storage and formulation challenges of pure sulforaphane. This is one reason many clinical studies use broccoli sprout preparations that either already contain sulforaphane or pair glucoraphanin with myrosinase to standardize delivery.
Glucoraphanin, abundant in seed, is the precursor of sulforaphane, the isothiocyanate formed by the hydrolysis of glucoraphanin by myrosinase. The enzyme myrosinase is naturally present in the plant and is released from plant vacuoles after mechanical stress — for example, during cutting or chewing.
When the plant cell structure is damaged (e.g., by chewing, cutting, or blending), myrosinase comes into contact with glucoraphanin. This interaction triggers hydrolysis, breaking down glucoraphanin into an unstable intermediate, which then rearranges to form sulforaphane.
Myrosinase-like activity also occurs in human intestinal microflora, so if glucoraphanin is consumed by itself, gut microflora will convert a portion of it to sulforaphane. As in many types of metabolism modulated by the microbiome, this conversion rate varies from individual to individual.
Broccoli sprout extract (BSE) rich in glucoraphanin has the lowest average bioavailability (~10%), while the bioavailability of BSE containing glucoraphanin plus myrosinase is approximately 35%, and the bioavailability of sulforaphane-rich BSE is ~70% (bioavailability varies significantly among individuals).
When either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable. The bioavailability of sulforaphane derived from glucoraphanin can vary significantly. Factors influencing this include the amount of glucoraphanin consumed, the activity of myrosinase (both plant-derived and gut microbial), individual gut microbiome composition, and food preparation methods.
The beneficial effects of sulforaphane (derived from glucoraphanin) are due to its antioxidant and anti-inflammatory properties. Sulforaphane activates NF-E2-related factor 2 (Nrf2), a basic leucine zipper transcription factor that serves as a defense mechanism against oxidative stress and electrophilic toxicants by inducing more than a hundred cytoprotective proteins, including antioxidants and phase II detoxifying enzymes.
Sulforaphane-mediated KEAP1 modification releases NRF2 from degradation and results in NRF2 phosphorylation and nuclear translocation. Within the nucleus, NRF2 binds to promoter regions of target genes which contain antioxidant response element (ARE) sequences, ultimately inducing the transcription of cytoprotective genes, i.e., those encoding phase II enzymes.
The main mechanism of action involves regulation of the Nrf2–ARE pathway; this in turn upregulates the expression of a range of antioxidant enzymes including HO-1, NQO1, GST, γ-glutamyl cysteine ligase (GCL), and glutathione reductase (GR). Therefore, sulforaphane has been considered to act as an indirect antioxidant and a highly potent inducer of phase II cytoprotective enzymes. The resultant detoxification of electrophiles and oxidants can protect against carcinogens, oxidative stress, and inflammation.
Compared with widely used phytochemical-based supplements like curcumin, silymarin, and resveratrol, sulforaphane more potently activates Nrf2 to induce the expression of a battery of cytoprotective genes.
Upon activation, Nrf2 mediates antioxidant response by the induction of a broad range of genes including phase 2 enzymes, such as NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase-1, and antioxidant proteins, such as SOD and catalase. Sulforaphane has been reported to promote detoxification and elimination of aflatoxin, acetaldehyde, methylmercury, acrolein, benzene, crotonaldehyde, and free radicals through the Nrf2-mediated mechanism.
A compound which activates Phase I and Phase II enzymes is known as a bifunctional inducer; however, if it activates only Phase II enzymes, it is a monofunctional inducer. Phase II enzymes are induced by Nrf2 and as such are integral to this discussion. For safe and efficient detoxification, a toxin will ideally undergo a relatively slow Phase I reaction followed by a more rapid Phase II; this tends to prevent accumulation of the Phase I metabolite which can be more toxic than its precursor. Therefore, for an optimal cellular detoxification environment, Phase II reactions should be at a rate which prevents intermediate products of Phase I from accumulating.
Sulforaphane also exerts effects by upregulating the Keap1–Nrf2 nuclear transcription pathway, inhibiting the pro-inflammatory NF-κB cascade, upregulating heat-shock proteins, inhibiting histone de-acetylation, and reducing advanced glycation end-products (AGEs).
Enhanced Nrf2 signaling and DNA damage repair by sulforaphane interfere with cancer stem cells as well as carcinogen detoxification. Sulforaphane demonstrates an inhibitory effect on tumor development initiation and increases the sensitivity of cancer cells to chemotherapeutics, interfering with various signaling pathways, including induction of cell cycle arrest and apoptosis and anti-inflammatory action.
Note on evidence strength: The large majority of studies in this area use sulforaphane, not glucoraphanin itself, as the intervention. Clinical research on glucoraphanin per se is more limited; most human clinical findings apply to sulforaphane derived from glucoraphanin-containing preparations. Where the human evidence is preliminary, weak, or limited, this is stated explicitly.
Since first isolated from broccoli and demonstrated to have cancer chemoprotective properties in rats in the early 1990s, over 3,000 publications have described sulforaphane's efficacy in rodent disease models, underlying mechanisms of action, or, to date, over 50 clinical trials examining pharmacokinetics, pharmacodynamics, and disease mitigation.
Overwhelming evidence points to sulforaphane's multitargeted actions operationally targeting core cell survival signaling pathways in tumor cells and enzyme induction mediated by the Nrf2-regulated transcriptions of genes encoding carcinogen detoxification and antioxidant enzymes.
In terms of carcinogen detoxification, a key clinical program was conducted in Qidong, China, an area with high rates of liver cancer linked to aflatoxin exposure. Modulation of the metabolism of airborne pollutants by glucoraphanin-rich and sulforaphane-rich broccoli sprout beverages in Qidong, China was published in Carcinogenesis (2012), and a dose-dependent detoxication of the airborne pollutant benzene in a randomized trial of broccoli sprout beverage in Qidong, China was published in American Journal of Clinical Nutrition (2019). Results suggest sulforaphane's potential in regulating redox and inflammatory pathways, improving metabolic and cardiovascular outcomes, and exerting anti-cancer and neuroprotective effects. For healthy subjects, sulforaphane enhanced detoxification and reduced inflammation.
Sulforaphane displays anti-microbial effects on pathogenic microbes within the gut. Sulforaphane has been demonstrated to have a direct anti-microbial effect on Helicobacter pylori bacterium via activating Nrf2. Clinical trials with broccoli sprout also decreased markers of H. pylori.
Evidence strength: Preclinical evidence is substantial; human clinical evidence in the carcinogen-detoxification domain is strong (multiple RCTs). Clinical evidence for direct tumor prevention or treatment in humans remains preliminary — most human oncology studies are early-phase or observational.
A study published in 2015 (Armah, Derdemezis et al., Molecular Nutrition and Food Research) found that cruciferous-rich diets have been associated with reduction in plasma LDL-cholesterol, and evidence from two independent human studies indicates that consumption of high glucoraphanin broccoli significantly reduces plasma LDL-C.
A clinical trial involving 54 T2DM participants showed that dietary intervention with high-glucoraphanin broccoli (400 g/week) reduced variation in lipid and amino acid metabolites, and tricarboxylic acid cycle intermediates, and finally could reduce the risk of cardiovascular disease (Armah & Traka et al., 2013).
Animal and human experiments have identified substantial sulforaphane-mediated protection from a range of cardiovascular diseases, including hypertension, atherosclerosis, ischemia-reperfusion injury, diabetes, and diabetic complications.
Evidence strength: Human evidence for LDL reduction is supported by two independent RCTs using high-glucoraphanin broccoli. Additional cardiovascular endpoints (hypertension, atherosclerosis) remain primarily supported by preclinical models.
In a 4-week parallel, randomized, double-blind placebo-controlled study including 81 human participants with type 2 diabetes, 10 g/day broccoli sprout powder (225 μmol sulforaphane daily) decreased fasting serum insulin and insulin resistance by 18.2 and 14.2%, respectively (Bahadoran et al., 2012).
Positive results were also seen in a randomized double-blind placebo-controlled study including 97 Scandinavian patients with type 2 diabetes. In this study, patients consumed broccoli sprout extract (150 μmol sulforaphane/day) or a placebo over a 12-week period. The glucoraphanin-rich broccoli sprout extract improved both fasting glucose and HbA1c (7.38–7.04%) in obese patients with dysregulated diabetes (BMI >30 kg/m²; HbA1c > 50 mmol/mol) (Axelsson et al., 2017). The authors noted that this reduction in HbA1c was likely to reflect a clinically meaningful effect, as an HbA1c of 7% is the treatment goal of the American Diabetes Association.
Glucoraphanin, a stable glucosinolate precursor of sulforaphane, is mainly derived from broccoli sprouts. In both rodents and humans, glucoraphanin is hydrolyzed by gut microbiota-derived myrosinase into bioactive sulforaphane before intestinal absorption.
Evidence strength: Moderate. Two well-designed RCTs have shown clinically meaningful improvements in glycemic control in type 2 diabetes. Findings need replication in larger and more diverse populations.
The levels of serum biomarkers of liver function, including alanine aminotransferases (ALT), γ-glutamyl transpeptidase (γ-GT), alkaline phosphatase (ALP), and urinary level of 8-OHdG, an oxidative stress marker, were significantly decreased in subjects after a daily supplementation of broccoli sprout extract containing 30 mg of glucoraphanin for 2 months (Kikuchi et al., 2015). Although only a small group of subjects were enrolled and broccoli sprout extract was used instead of sulforaphane alone, the findings are still valuable.
At 69 μmol/day glucoraphanin for 60 days, plasma levels of liver function enzymes, including alanine aminotransferase (ALT) and γ-glutamyl transpeptidase (γ-GTP), were decreased in 55 male participants.
Evidence strength: Preliminary. Small human studies show biochemical improvements in liver function markers; larger controlled trials are needed.
Given sulforaphane's ability to activate NRF2-mediated cytoprotective mechanisms, it has emerged as a promising candidate for therapeutic intervention in neurodegenerative and neurodevelopmental disorders.
Sulforaphane crosses the blood–brain barrier and has general but potent indirect anti-oxidant and anti-inflammatory activities which function systemically.
Regarding autism spectrum disorder (ASD): A randomized double-blind placebo-controlled multi-center trial examined the efficacy of sulforaphane in treatment of children with autism spectrum disorder (Ou et al., 2024; published in Journal of Autism and Developmental Disorders).
Regarding schizophrenia: Among published clinical trials grouped in the neurodevelopmental and neuropsychiatric disorders category, two targeted patients with schizophrenia (Dickerson et al., 2021; Huang et al., 2025), one examined depression, and the last focused on another neuropsychiatric condition. Supplementation with sulforaphane-rich broccoli sprout extract for 8 weeks was effective for the treatment of cognitive impairment in medicated patients with schizophrenia, although other scores (such as psychotic symptoms) were not altered.
Animal preclinical evidence for neuroprotection: The dietary intake of glucoraphanin (a glucosinolate precursor of sulforaphane) during the juvenile and adolescence prevented the onset of phencyclidine (PCP)-induced cognitive deficits as well as the increase in 8-oxo-dG-positive cells and the decrease in parvalbumin-positive cells in the brain at adulthood.
Evidence strength: Overall weak to preliminary for specific neurological conditions. Human clinical trials exist for ASD and schizophrenia, but these are mostly small, early-phase, or open-label. Larger confirmatory RCTs are needed. Preclinical evidence is strong.
In dermatologic studies, sulforaphane has been shown to provide robust protection against the erythema induced by UVB or simulated solar irradiation when topically applied to the skin of healthy human volunteers. One study reported positive effects on melanoma (atypical nevi) following 50, 100, or 200 micromoles of sulforaphane in broccoli sprout extract, daily, for 28 days.
Other pharmacodynamic effects of interventions with glucoraphanin/sulforaphane in humans include increase in the levels of reduced glutathione in brain, enhanced integration of fatty acid β-oxidation with TCA cycle activity, protection against skin erythema caused by exposure to ultraviolet radiation, and reduction in plasma LDL-cholesterol.
Evidence strength: Moderate for UVB protection (topical application); preliminary for systemic oral use in skin disorders.
Sulforaphane has been evaluated for its potential to ameliorate or prevent symptoms of autism, air pollution injury, chronic obstructive pulmonary disease (COPD), asthma, and chemically induced liver toxicity in human volunteers. Clinical trials conducted in Qidong, China directly tested glucoraphanin-rich and sulforaphane-rich beverages for their ability to accelerate the excretion of airborne pollutants including benzene, a documented human carcinogen.
Evidence strength: Moderate for carcinogen detoxification biomarkers in controlled trials; clinical outcomes (e.g., cancer rates) remain to be demonstrated in long-term studies.
Treatment with sulforaphane induces pharmacological Nrf2 activation, subsequently affecting adipocyte differentiation and preventing adipogenesis and lipid accumulation. Emerging evidence has demonstrated the safety of orally administered glucoraphanin. Animal studies using glucoraphanin in high-fat diet models have demonstrated favorable metabolic effects, but controlled human trials focused specifically on obesity are still ongoing.
Evidence strength: Primarily preclinical (animal models). Human evidence is limited.
Based on published research, glucoraphanin (via its metabolite sulforaphane) has been investigated in relation to the following body systems and health domains:
Dosages in the scientific literature are reported variably in milligrams (mg), micromoles (μmol), or in terms of the containing food/extract preparation. In nutrition papers, doses are often reported in micromoles (μmol). Sulforaphane has a molecular mass of ~177.3 g/mol, so 1 mg ≈ 5.64 μmol. Glucoraphanin's molecular mass is ~437.5 g/mol, so 1 mg ≈ 2.29 μmol.
Specific doses documented in clinical studies include:
Host factors (genetic polymorphisms and epigenetics) as well as host-microbiome interactions likely play important roles in the wide inter-individual variability in pharmacokinetics seen in many clinical trial participants.
Glucoraphanin itself is generally considered non-toxic. Clinical studies support the safety of sulforaphane and its precursors in both food and supplement form. Although sulforaphane is widely recognized for its detoxification and antioxidant benefits, human studies have reported mild and infrequent adverse effects — mostly when high doses are used. The most frequently observed sulforaphane side effects are related to the gastrointestinal system. Side effects are rare and usually mild, such as gas or digestive discomfort, especially at higher doses.
BSE rich in glucoraphanin has the lowest average bioavailability (~10%), while the bioavailability of BSE containing glucoraphanin plus myrosinase is approximately 35%, and that of sulforaphane-rich BSE is ~70%. Many commercial BSE supplements do not contain the amount of sulforaphane or glucoraphanin claimed on their labels. This has direct implications for the reliability and comparability of clinical findings.
Glucosinolates have a long-standing reputation as "goitrogens," meaning they can potentially interfere with thyroid function. Cruciferous vegetables, including broccoli sprouts, contain compounds called goitrogens, which can interfere with thyroid hormone production when consumed in very large quantities. Sulforaphane is one such compound, although it is generally less potent as a goitrogen than other raw cruciferous compounds. Most people eating normal portions of broccoli sprouts will not see thyroid problems. Excessive intake — especially in raw form — can raise goitrogenic effects.
Goitrogenic metabolites can be formed without myrosinase, meaning the inactivation of myrosinase during cooking would have no effect on the anti-nutritional effect of glucosinolates in cruciferous vegetables.
In clinical trials, Nrf2 pathways enhanced by synthetic agonists exhibited adverse cardiac events and gastrointestinal toxicities. While this has not been documented for glucoraphanin at food-based doses, it underscores the dose-dependency of Nrf2 activation. At a dose of under 600 μmol/day of glucoraphanin, authors noted that such a high dose may induce pharmacologic effects that require careful examination before the performance of any study.
Even if plant myrosinase is inactivated (e.g., by cooking), a portion of ingested glucoraphanin can still be converted to sulforaphane by certain bacteria in the human gut that possess myrosinase-like activity. This means that even cooked cruciferous vegetables can provide some sulforaphane, though likely less efficiently than raw consumption. One practical approach is to chop vegetables and let them sit for about 10 minutes before cooking. This gives the myrosinase time to do its work before heat inactivates it.
Analyses of commercial broccoli sprout supplement products have found that many products do not contain the amount of sulforaphane or glucoraphanin claimed on the label. Many commercial broccoli supplements fail to provide adequate or consistent levels of active compounds. For meaningful biological effects, products must contain both glucoraphanin and myrosinase — the precursor and enzyme pair essential for in vivo sulforaphane formation.
There is a striking need to develop rigorous biomarkers of pharmacodynamic action. Better links between purported mechanisms of action delineated in the pre-clinical settings and functional assessments of clinical efficacy are needed to optimize interventions and to better identify those healthy or at-risk groups that might best benefit. There is currently a lack of randomized controlled trials in several areas, highlighting the importance of using animal data to inform trials investigating similar outcomes in humans.
Health conditions that Glucoraphanin may help support.
Body systems that Glucoraphanin may help support.
Go back