What is sulforaphane?

Sulforaphane is a compound your body makes from a precursor called glucoraphanin, which is found in broccoli, broccoli sprouts, and other cruciferous vegetables. It activates a master switch called Nrf2 that turns on more than 200 of your own antioxidant and detox genes. The richest natural source is 3-day-old broccoli sprouts.

Why are broccoli sprouts better than mature broccoli for sulforaphane?

Broccoli sprouts contain 50 to 100 times more glucoraphanin than mature broccoli. They are also typically eaten raw, which preserves the myrosinase enzyme that converts the precursor into active sulforaphane. Cooked broccoli has very little activity, because heat destroys myrosinase.

How do I take a sulforaphane supplement properly?

Take a sulforaphane supplement that combines glucoraphanin with active myrosinase, ideally with a meal that contains some fat. If your product does not include myrosinase, swallow the capsule with a quarter teaspoon of ground mustard seed, which is naturally rich in the enzyme. Daily dosing keeps the Nrf2 pathway active.

Is sulforaphane safe to take every day?

Sulforaphane is generally safe to take every day at moderate doses (10 to 40 mg) for healthy adults. The main caution is around thyroid disease (high goitrogen intake can worsen hypothyroidism) and active cancer treatment (constant Nrf2 activation may interfere with some chemotherapies). Talk with your physician if either applies.

Can sulforaphane help with detoxification from air pollution?

Sulforaphane has clinical evidence for supporting detoxification from urban air pollutants, including benzene and acrolein. A trial in heavily polluted areas of China showed substantial increases in the excretion of these compounds. For Philadelphians near I-95, broccoli sprouts and a sulforaphane-rich diet are reasonable strategies.

Does sulforaphane prevent cancer?

Sulforaphane is associated with reduced risk of several cancers in population studies and in lab models, mostly through Phase II detoxification and DNA repair pathways. It is not a guaranteed prevention strategy, and "cure" or "prevent" is too strong for the current evidence. We treat it as one piece of a broader prevention plan.

What is the best time of day to take sulforaphane?

The best time to take sulforaphane is with a meal, ideally one that contains some healthy fat. Morning or midday dosing pairs well with breakfast or lunch, but timing matters less than consistency. Daily dosing keeps the Nrf2 system upregulated for that 72-hour window of effect.

Can I get enough sulforaphane from food alone?

You can get enough sulforaphane from food alone if you eat raw cruciferous vegetables (particularly sprouts) regularly. About 2 ounces of broccoli sprouts daily is a reasonable target. If you do not enjoy sprouts or struggle with consistency, a glucoraphanin-plus-myrosinase supplement is a fair substitute.

What is the Nrf2 pathway, in simple terms?

The Nrf2 pathway is your bodys master regulator of antioxidant and detoxification genes. When Nrf2 is activated, it switches on more than 200 protective genes, including those that make glutathione, your bodys primary internal antioxidant. Sulforaphane is one of the most potent natural Nrf2 activators known.

How is sulforaphane different from vitamin C and E?

Vitamin C and E are direct antioxidants that neutralize free radicals on contact. Sulforaphane does not neutralize free radicals directly. Instead, it signals your cells to build their own antioxidant defenses, which is a far more sustained effect. This is why sulforaphane is sometimes called an "indirect antioxidant" or a hormetic agent.

Can sulforaphane interfere with chemotherapy?

Sulforaphane can interfere with some chemotherapy regimens because constant Nrf2 activation in existing cancer cells may promote drug resistance. The data is most concerning for certain platinum-based and alkylating chemotherapies. Patients in active cancer treatment should always check with their oncologist before adding sulforaphane.

How does sulforaphane support brain health?

Sulforaphane supports brain health by reducing oxidative stress, lowering neuroinflammation, and supporting blood-brain barrier function. Animal studies suggest it may protect against traumatic brain injury when given before the injury, and small clinical trials show benefit in autism and schizophrenia. Most of the human data is still early.

Can sulforaphane help with insulin resistance?

Sulforaphane can help with insulin resistance in some patients, partly through reduced hepatic (liver) glucose production. A clinical trial in obese diabetic patients showed improvements in fasting glucose and HbA1c. The effect is modest, so it is a helper, not a replacement for diet, exercise, and medication when needed.

What is the link between Nrf2 and aging?

Nrf2 activity tends to decline with age, which contributes to higher oxidative stress and reduced detoxification capacity in older adults. Sulforaphane is one of the most studied tools for supporting Nrf2 function. Pairing it with sleep, exercise, and other Nrf2 activators (like intermittent fasting) compounds the effect.

How do I grow broccoli sprouts at home?

Growing broccoli sprouts at home requires a quart-sized glass jar with a mesh lid, organic broccoli sprouting seeds, and 3 to 4 days. Soak about 2 tablespoons of seeds overnight, drain, and rinse twice daily until small green sprouts appear with tiny leaves. Eat raw within a week. The cost is roughly 50 cents per ounce of finished sprouts.

What is the role of glutathione, and how does sulforaphane support it?

Glutathione is the bodys primary internal antioxidant and the central cofactor for Phase II detoxification. Sulforaphane increases glutathione production by upregulating the enzymes that synthesize it. Pairing sulforaphane with NAC, which supplies cysteine (the rate-limiting building block of glutathione), is a common precision strategy.

Are there people who should avoid sulforaphane?

Sulforaphane should be approached carefully by patients in active cancer treatment, those with severe hypothyroidism or iodine deficiency, and pregnant women using high-dose supplements. Most healthy adults can use it safely, but checking with your physician is wise if you are in any of those categories.

How does sulforaphane fit into a healthspan plan?

Sulforaphane fits into a healthspan plan as a daily Nrf2 activator that supports detoxification, metabolic health, and resilience to environmental stress. It is one tool among many. The biggest wins still come from sleep, exercise, food quality, and stress management, with sulforaphane as a precision add-on.

Will sulforaphane help with a fatty liver?

Sulforaphane has early evidence for supporting fatty liver disease (also called metabolic-associated steatotic liver disease) through reduced oxidative stress and improved insulin sensitivity. The data is not yet strong enough to call it a treatment, but it is a reasonable supportive tool in a broader plan that includes weight loss, exercise, and dietary change.

How does Philadelphias air quality affect my detox needs?

Philadelphias location near I-95, refineries, and industrial corridors raises exposure to traffic-related particles, ozone, and combustion byproducts. Long-term residents often carry a higher background load of oxidative stress. Sulforaphane is one of the more relevant tools in this setting, because it directly supports the Phase II enzymes that detoxify common urban pollutants.

How will I know sulforaphane is working?

You will know sulforaphane is working through subtle but measurable changes: better skin tone, lower fasting glucose, better recovery from heavy training, and improvements in markers of oxidative stress on detailed labs. Most effects are silent and preventive rather than sensational. If after 12 weeks you see no changes in any tracked metric, the strategy needs to evolve.

What is sulforaphane?

Sulforaphane is a compound your body makes from a precursor called glucoraphanin, which is found in broccoli, broccoli sprouts, and other cruciferous vegetables. It activates a master switch called Nrf2 that turns on more than 200 of your own antioxidant and detox genes. The richest natural source is 3-day-old broccoli sprouts.

Why are broccoli sprouts better than mature broccoli for sulforaphane?

Broccoli sprouts contain 50 to 100 times more glucoraphanin than mature broccoli. They are also typically eaten raw, which preserves the myrosinase enzyme that converts the precursor into active sulforaphane. Cooked broccoli has very little activity, because heat destroys myrosinase.

How do I take a sulforaphane supplement properly?

Take a sulforaphane supplement that combines glucoraphanin with active myrosinase, ideally with a meal that contains some fat. If your product does not include myrosinase, swallow the capsule with a quarter teaspoon of ground mustard seed, which is naturally rich in the enzyme. Daily dosing keeps the Nrf2 pathway active.

Is sulforaphane safe to take every day?

Sulforaphane is generally safe to take every day at moderate doses (10 to 40 mg) for healthy adults. The main caution is around thyroid disease (high goitrogen intake can worsen hypothyroidism) and active cancer treatment (constant Nrf2 activation may interfere with some chemotherapies). Talk with your physician if either applies.

Can sulforaphane help with detoxification from air pollution?

Sulforaphane has clinical evidence for supporting detoxification from urban air pollutants, including benzene and acrolein. A trial in heavily polluted areas of China showed substantial increases in the excretion of these compounds. For Philadelphians near I-95, broccoli sprouts and a sulforaphane-rich diet are reasonable strategies.

Does sulforaphane prevent cancer?

Sulforaphane is associated with reduced risk of several cancers in population studies and in lab models, mostly through Phase II detoxification and DNA repair pathways. It is not a guaranteed prevention strategy, and "cure" or "prevent" is too strong for the current evidence. We treat it as one piece of a broader prevention plan.

What is the best time of day to take sulforaphane?

The best time to take sulforaphane is with a meal, ideally one that contains some healthy fat. Morning or midday dosing pairs well with breakfast or lunch, but timing matters less than consistency. Daily dosing keeps the Nrf2 system upregulated for that 72-hour window of effect.

Can I get enough sulforaphane from food alone?

You can get enough sulforaphane from food alone if you eat raw cruciferous vegetables (particularly sprouts) regularly. About 2 ounces of broccoli sprouts daily is a reasonable target. If you do not enjoy sprouts or struggle with consistency, a glucoraphanin-plus-myrosinase supplement is a fair substitute.

What is the Nrf2 pathway, in simple terms?

The Nrf2 pathway is your bodys master regulator of antioxidant and detoxification genes. When Nrf2 is activated, it switches on more than 200 protective genes, including those that make glutathione, your bodys primary internal antioxidant. Sulforaphane is one of the most potent natural Nrf2 activators known.

How is sulforaphane different from vitamin C and E?

Vitamin C and E are direct antioxidants that neutralize free radicals on contact. Sulforaphane does not neutralize free radicals directly. Instead, it signals your cells to build their own antioxidant defenses, which is a far more sustained effect. This is why sulforaphane is sometimes called an "indirect antioxidant" or a hormetic agent.

Can sulforaphane interfere with chemotherapy?

Sulforaphane can interfere with some chemotherapy regimens because constant Nrf2 activation in existing cancer cells may promote drug resistance. The data is most concerning for certain platinum-based and alkylating chemotherapies. Patients in active cancer treatment should always check with their oncologist before adding sulforaphane.

How does sulforaphane support brain health?

Sulforaphane supports brain health by reducing oxidative stress, lowering neuroinflammation, and supporting blood-brain barrier function. Animal studies suggest it may protect against traumatic brain injury when given before the injury, and small clinical trials show benefit in autism and schizophrenia. Most of the human data is still early.

Can sulforaphane help with insulin resistance?

Sulforaphane can help with insulin resistance in some patients, partly through reduced hepatic (liver) glucose production. A clinical trial in obese diabetic patients showed improvements in fasting glucose and HbA1c. The effect is modest, so it is a helper, not a replacement for diet, exercise, and medication when needed.

What is the link between Nrf2 and aging?

Nrf2 activity tends to decline with age, which contributes to higher oxidative stress and reduced detoxification capacity in older adults. Sulforaphane is one of the most studied tools for supporting Nrf2 function. Pairing it with sleep, exercise, and other Nrf2 activators (like intermittent fasting) compounds the effect.

How do I grow broccoli sprouts at home?

Growing broccoli sprouts at home requires a quart-sized glass jar with a mesh lid, organic broccoli sprouting seeds, and 3 to 4 days. Soak about 2 tablespoons of seeds overnight, drain, and rinse twice daily until small green sprouts appear with tiny leaves. Eat raw within a week. The cost is roughly 50 cents per ounce of finished sprouts.

What is the role of glutathione, and how does sulforaphane support it?

Glutathione is the bodys primary internal antioxidant and the central cofactor for Phase II detoxification. Sulforaphane increases glutathione production by upregulating the enzymes that synthesize it. Pairing sulforaphane with NAC, which supplies cysteine (the rate-limiting building block of glutathione), is a common precision strategy.

Are there people who should avoid sulforaphane?

Sulforaphane should be approached carefully by patients in active cancer treatment, those with severe hypothyroidism or iodine deficiency, and pregnant women using high-dose supplements. Most healthy adults can use it safely, but checking with your physician is wise if you are in any of those categories.

How does sulforaphane fit into a healthspan plan?

Sulforaphane fits into a healthspan plan as a daily Nrf2 activator that supports detoxification, metabolic health, and resilience to environmental stress. It is one tool among many. The biggest wins still come from sleep, exercise, food quality, and stress management, with sulforaphane as a precision add-on.

Will sulforaphane help with a fatty liver?

Sulforaphane has early evidence for supporting fatty liver disease (also called metabolic-associated steatotic liver disease) through reduced oxidative stress and improved insulin sensitivity. The data is not yet strong enough to call it a treatment, but it is a reasonable supportive tool in a broader plan that includes weight loss, exercise, and dietary change.

How does Philadelphias air quality affect my detox needs?

Philadelphias location near I-95, refineries, and industrial corridors raises exposure to traffic-related particles, ozone, and combustion byproducts. Long-term residents often carry a higher background load of oxidative stress. Sulforaphane is one of the more relevant tools in this setting, because it directly supports the Phase II enzymes that detoxify common urban pollutants.

How will I know sulforaphane is working?

You will know sulforaphane is working through subtle but measurable changes: better skin tone, lower fasting glucose, better recovery from heavy training, and improvements in markers of oxidative stress on detailed labs. Most effects are silent and preventive rather than sensational. If after 12 weeks you see no changes in any tracked metric, the strategy needs to evolve.

Sulforaphane Clinical Guide | Fishtown Medicine

TL;DR30-second take

Sulforaphane is a compound your body makes from glucoraphanin, a precursor found in cruciferous vegetables, most abundantly in 3-day-old broccoli sprouts (which contain 50 to 100 times more glucoraphanin than mature broccoli). It activates the Nrf2 pathway, a master switch that turns on more than 200 antioxidant and detoxification genes, including Phase II enzymes that clear carcinogens and urban pollutants. The practical dose is 10 to 40 mg per day from raw sprouts or a glucoraphanin-plus-myrosinase supplement. The main caution: in existing cancer cells, sustained Nrf2 activation may promote chemotherapy resistance, so patients in active cancer treatment must discuss this with their oncologist first.

Sulforaphane is not just another antioxidant. It is a hormetic compound, something that creates mild, helpful cellular stress, that activates the bodys own defense systems rather than neutralizing free radicals on the spot. The richest source is 3-day-old broccoli sprouts, and the key to switching on its activity is an enzyme called myrosinase.

What sulforaphane is and what it does

Sulforaphane is an isothiocyanate, a sulfur-containing plant compound, made from glucoraphanin, a glucosinolate found in cruciferous vegetables like broccoli, cabbage, and kale. Its main job is to activate the Nrf2 pathway (nuclear factor erythroid 2-related factor 2), arguably the most important cellular defense system most people have never heard of.

Under normal conditions, Nrf2 is held inactive by a partner protein called Keap1 (Kelch-like ECH-associated protein 1), which constantly tags Nrf2 for breakdown. Sulforaphane modifies specific cysteine residues on Keap1, causing it to release Nrf2. Once free, Nrf2 moves into the cell nucleus and binds to Antioxidant Response Elements (AREs) in DNA, switching on more than 200 genes that produce antioxidants (glutathione, catalase, superoxide dismutase), Phase II detoxification enzymes (GSTs, NQO1, UDP-glucuronosyltransferases), anti-inflammatory mediators, and DNA repair tools. The upregulation lasts about 72 hours, providing sustained protection.

This is the key distinction from vitamin C: vitamin C donates electrons to neutralize free radicals on contact. Sulforaphane signals your cells to build their own defense team. In healthy cells, Nrf2 activation is protective. In existing cancer cells, however, constant Nrf2 activation can sometimes promote tumor growth and chemotherapy resistance. This is why sulforaphane is studied for cancer prevention, not as a treatment for active cancer.

Who this is for (and who it isnt)

Sulforaphane has clinical relevance across several patient profiles.

It tends to help:

Cancer prevention. Phase II enzyme induction detoxifies carcinogens including benzene, polycyclic aromatic hydrocarbons (from grilled meat, air pollution, smoke), and aflatoxins. It also promotes apoptosis in pre-cancerous cells and inhibits histone deacetylase, an epigenetic effect that reactivates tumor suppressor genes. Population studies show high cruciferous vegetable intake is associated with reduced risk of prostate, breast, colorectal, and lung cancers.
Environmental detoxification. A clinical trial in China showed sulforaphane increased urinary excretion of benzene by 61% and acrolein by 23%. It also enhances glutathione-driven detoxification of lead, cadmium, and mercury. This is particularly relevant for Philadelphians living near I-95 or industrial corridors.
Metabolic health and type 2 diabetes. A 2017 randomized controlled trial in Science Translational Medicine showed sulforaphane reduced fasting blood glucose and HbA1c in obese patients with type 2 diabetes, through reduced hepatic glucose production.
Brain and mood support. Emerging evidence includes improvements in social and verbal behavior in a small randomized controlled trial in autism spectrum disorder over 18 weeks, improved cognitive function and reduced oxidative stress markers in schizophrenia studies, and potential for depression through reduced neuroinflammation.
Skin protection. Sulforaphane supports skin defense from UV damage by reducing redness and helping prevent photoaging.
Preventive maintenance generally. Animal models of traumatic brain injury show sulforaphane given before injury significantly reduced blood-brain barrier permeability, brain swelling, and neuronal damage. Given after the injury, the benefit was much smaller. Think of it like fire sprinklers: they work because they are already installed when the fire starts.

It is not the right tool, or needs a careful conversation first, for:

Patients in active cancer treatment. Constant Nrf2 activation in existing cancer cells may promote chemotherapy resistance, most concerning for certain platinum-based and alkylating chemotherapies. Always discuss with your oncologist before starting.
Patients with severe hypothyroidism or iodine deficiency. Cruciferous vegetables contain goitrogens (compounds that can interfere with iodine uptake by the thyroid). For most people with adequate iodine intake, normal cruciferous consumption is safe. Very high raw intake (over 200 g daily) may worsen thyroid function in vulnerable patients.
Pregnancy (high-dose supplements). Generally safe as part of normal dietary intake. Stick to food sources rather than high-dose supplements during pregnancy.

How we evaluate it: safety, then effectiveness, then cost

Every supplement we recommend runs the same 3 gates, in order (we go deep on this in how we choose supplements).

Safety first. The safety screen includes medication review (chemotherapy, levothyroxine, warfarin) and thyroid status for patients considering high-dose supplementation. Sulforaphane can affect cytochrome P450 enzymes in theory, and cruciferous vegetables contain vitamin K, which is relevant for warfarin and INR monitoring.
Effectiveness second. The single biggest effectiveness variable is myrosinase. Glucoraphanin is the stable, inactive precursor; myrosinase is the enzyme that converts it into active sulforaphane. Cooking broccoli above 160 degrees Fahrenheit destroys myrosinase and can reduce sulforaphane yield by up to 90%. A glucoraphanin-plus-myrosinase supplement (or raw sprouts eaten with thorough chewing) is the only reliable delivery method. Brands like Avmacol or BroccoMax (with added mustard seed extract) supply the enzyme. If using a glucoraphanin-only supplement, swallow it with a quarter teaspoon of ground mustard seed, a natural myrosinase source that can rescue conversion efficiency from about 10% up toward 40%.
Cost last. Among options that solve the myrosinase problem, we take the best value. Growing broccoli sprouts at home in a quart jar costs roughly 50 cents per ounce of finished sprouts, making it the most cost-effective option for patients willing to do it.

How to dose it, and when

The right dose depends on the goal and the form.

Cancer prevention and general detox. 10 to 20 mg of sulforaphane daily.
Metabolic and diabetes support. 20 to 40 mg daily.
Neurodevelopmental research doses (autism, schizophrenia). Up to 50 to 100 mg daily, under medical supervision.

How to achieve those doses in practice:

Raw broccoli sprouts. 30 to 60 g (1 to 2 oz) daily delivers roughly 5 to 60 mg depending on sprout age and freshness. Whole food, high bioavailability, inexpensive to grow at home.
Sprout powder with myrosinase. 1 to 2 g daily. Convenient and standardized, but quality varies; verify active myrosinase is present.
Glucoraphanin only. 200 to 400 mg daily. Shelf stable and convenient, but relies on gut bacteria for conversion (1 to 40% efficiency person to person); pair with mustard seed.
Glucoraphanin plus myrosinase. 100 to 200 mg daily. High bioavailability and consistent conversion. More expensive but preferred.

Timing and preparation: eat sprouts raw in salads, sandwiches, or blended into a smoothie. Chew thoroughly to crush the cells and release myrosinase. Take supplements with a meal that contains some fat. Daily consistency matters more than exact timing, because Nrf2 activation peaks 24 to 48 hours after intake and lasts about 72 hours, so daily dosing keeps the system upregulated.

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Sulforaphane stacks well with NAC (N-acetylcysteine) at 600 to 1,200 mg (NAC supplies cysteine, the rate-limiting building block for glutathione that sulforaphanes GST enzymes use), quercetin at 500 to 1,000 mg, curcumin at 500 to 1,000 mg with piperine, green tea extract (EGCG) at 200 to 400 mg, and resveratrol at 150 to 500 mg.

Flaws, side effects, and interactions

Being honest about the downsides is part of the job.

GI effects. High doses, particularly with raw sprouts, may cause bloating or gas. Start low and titrate up.
Goitrogen concern. Very high raw cruciferous intake (over 200 g daily) can worsen thyroid function in patients with iodine deficiency or hypothyroidism. Cooking reduces goitrogen activity but also reduces sulforaphane yield, so balance matters.
Active cancer paradox. While sulforaphane is protective for cancer prevention, constant Nrf2 activation in existing cancer cells may promote chemotherapy resistance. This is not a concern for prevention; it is a concern for patients in active treatment.
Drug interactions (key interactions):
- Thyroid hormone (levothyroxine): goitrogens may reduce iodine absorption; monitor TSH and ensure adequate iodine intake.
- Chemotherapy (select agents): may reduce efficacy via Nrf2 in cancer cells; discuss with oncologist and avoid during active treatment.
- Warfarin: cruciferous vegetables contain vitamin K; monitor INR. Sulforaphane itself is low risk at typical doses.
Pregnancy. Generally safe as part of normal dietary intake. High-dose supplements during pregnancy require physician guidance.

We look for: a glucoraphanin-plus-myrosinase supplement (Avmacol, BroccoMax with mustard seed extract, or a comparable standardized product), or raw 3-day-old broccoli sprouts eaten daily. Third-party testing for purity in any supplement form.
Worth considering alongside: NAC for glutathione substrate, quercetin or curcumin for synergistic Nrf2 activation. Garlic, onions, berries, and green tea broaden the antioxidant base and stack well with sulforaphane.
We dont lean on: cooked broccoli as a primary sulforaphane source (heat destroys myrosinase and collapses yield below 1 mg per 100 g), glucoraphanin-only supplements without mustard seed supplementation in patients with low gut microbiome conversion, or doses above 40 mg daily without a clinical reason.

Guidance from the Clinic

"Sulforaphane is one of the more interesting tools in the precision medicine toolkit because it works upstream. Instead of neutralizing one free radical at a time like vitamin C does, it signals your cells to build their own defense team for the next 72 hours. For my patients near I-95 or in industrial corridors, that Phase II detoxification support is directly relevant to what they are breathing every day. The key is solving the myrosinase problem, either through raw sprouts or the right supplement form."

Dr. Ash

Actionable Steps

A simple weekly sulforaphane plan.

Build a sprout habit. Buy 3-day-old broccoli sprouts at Whole Foods or Riverwards Produce, or grow them at home in a quart jar. Aim for about 2 ounces per day.
Eat them raw. Add to salads, omelets after cooking, or smoothies. Cooking destroys the conversion enzyme.
If you prefer a supplement, choose glucoraphanin plus myrosinase. Look for Avmacol or a similar standardized product.
Pair with detox foods. Garlic, onions, berries, and green tea stack well with sulforaphane and broaden the antioxidant base.
Disclose to your oncologist or endocrinologist if you are in active cancer treatment or managing thyroid disease before starting.

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Key Takeaways

Sulforaphane activates the Nrf2 pathway, switching on more than 200 antioxidant and detoxification genes for about 72 hours after each dose.
The richest source is 3-day-old raw broccoli sprouts (50 to 100 times more glucoraphanin than mature broccoli); the myrosinase enzyme is essential and destroyed by heat above 160 degrees Fahrenheit.
Practical dose is 10 to 40 mg per day (general prevention to metabolic support), from raw sprouts or a glucoraphanin-plus-myrosinase supplement.
Patients in active cancer treatment and those with significant thyroid disease should consult their physician before starting.
Sulforaphane pairs well with NAC for glutathione support, and is particularly relevant for urban patients with high environmental pollutant exposure.

Scientific References

Fahey, J. W., et al. (1997). Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proceedings of the National Academy of Sciences, 94(19), 10367-10372.
Singh, K., et al. (2014). Sulforaphane treatment of young men with autism spectrum disorder. Proceedings of the National Academy of Sciences, 111(43), 15550-15555.
Axelsson, A. S., et al. (2017). Sulforaphane reduces hepatic glucose production and improves glucose control in patients with type 2 diabetes. Science Translational Medicine, 9(394), eaah4477.
Kensler, T. W., et al. (2013). Modulation of the metabolism of airborne pollutants by glucoraphanin-rich and sulforaphane-rich broccoli sprout beverages in Qidong, China. Carcinogenesis, 33(1), 101-107.

Fishtown Medicine | Articles

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Frequently Asked Questions

Common Questions

Deep-Dive Questions

Goitrogens are compounds in cruciferous vegetables that can interfere with iodine uptake by the thyroid. For most people with adequate iodine intake, normal cruciferous consumption is safe. For people with iodine deficiency or hypothyroidism, very high raw intake (over 200 g daily) may worsen thyroid function. Cooking reduces goitrogen activity but also reduces sulforaphane yield, so balance matters.

Ready when you are

Start your intake

Dr. Ash reads every intake himself, and answers questions personally - usually within a few hours.

TL;DR30-second take

What sulforaphane is and what it does

Who this is for (and who it isnt)

Sulforaphane has clinical relevance across several patient profiles.

It tends to help:

Cancer prevention. Phase II enzyme induction detoxifies carcinogens including benzene, polycyclic aromatic hydrocarbons (from grilled meat, air pollution, smoke), and aflatoxins. It also promotes apoptosis in pre-cancerous cells and inhibits histone deacetylase, an epigenetic effect that reactivates tumor suppressor genes. Population studies show high cruciferous vegetable intake is associated with reduced risk of prostate, breast, colorectal, and lung cancers.
Environmental detoxification. A clinical trial in China showed sulforaphane increased urinary excretion of benzene by 61% and acrolein by 23%. It also enhances glutathione-driven detoxification of lead, cadmium, and mercury. This is particularly relevant for Philadelphians living near I-95 or industrial corridors.
Metabolic health and type 2 diabetes. A 2017 randomized controlled trial in Science Translational Medicine showed sulforaphane reduced fasting blood glucose and HbA1c in obese patients with type 2 diabetes, through reduced hepatic glucose production.
Brain and mood support. Emerging evidence includes improvements in social and verbal behavior in a small randomized controlled trial in autism spectrum disorder over 18 weeks, improved cognitive function and reduced oxidative stress markers in schizophrenia studies, and potential for depression through reduced neuroinflammation.
Skin protection. Sulforaphane supports skin defense from UV damage by reducing redness and helping prevent photoaging.
Preventive maintenance generally. Animal models of traumatic brain injury show sulforaphane given before injury significantly reduced blood-brain barrier permeability, brain swelling, and neuronal damage. Given after the injury, the benefit was much smaller. Think of it like fire sprinklers: they work because they are already installed when the fire starts.

It is not the right tool, or needs a careful conversation first, for:

Patients in active cancer treatment. Constant Nrf2 activation in existing cancer cells may promote chemotherapy resistance, most concerning for certain platinum-based and alkylating chemotherapies. Always discuss with your oncologist before starting.
Patients with severe hypothyroidism or iodine deficiency. Cruciferous vegetables contain goitrogens (compounds that can interfere with iodine uptake by the thyroid). For most people with adequate iodine intake, normal cruciferous consumption is safe. Very high raw intake (over 200 g daily) may worsen thyroid function in vulnerable patients.
Pregnancy (high-dose supplements). Generally safe as part of normal dietary intake. Stick to food sources rather than high-dose supplements during pregnancy.

How we evaluate it: safety, then effectiveness, then cost

Every supplement we recommend runs the same 3 gates, in order (we go deep on this in how we choose supplements).

Safety first. The safety screen includes medication review (chemotherapy, levothyroxine, warfarin) and thyroid status for patients considering high-dose supplementation. Sulforaphane can affect cytochrome P450 enzymes in theory, and cruciferous vegetables contain vitamin K, which is relevant for warfarin and INR monitoring.
Effectiveness second. The single biggest effectiveness variable is myrosinase. Glucoraphanin is the stable, inactive precursor; myrosinase is the enzyme that converts it into active sulforaphane. Cooking broccoli above 160 degrees Fahrenheit destroys myrosinase and can reduce sulforaphane yield by up to 90%. A glucoraphanin-plus-myrosinase supplement (or raw sprouts eaten with thorough chewing) is the only reliable delivery method. Brands like Avmacol or BroccoMax (with added mustard seed extract) supply the enzyme. If using a glucoraphanin-only supplement, swallow it with a quarter teaspoon of ground mustard seed, a natural myrosinase source that can rescue conversion efficiency from about 10% up toward 40%.
Cost last. Among options that solve the myrosinase problem, we take the best value. Growing broccoli sprouts at home in a quart jar costs roughly 50 cents per ounce of finished sprouts, making it the most cost-effective option for patients willing to do it.

How to dose it, and when

The right dose depends on the goal and the form.

Cancer prevention and general detox. 10 to 20 mg of sulforaphane daily.
Metabolic and diabetes support. 20 to 40 mg daily.
Neurodevelopmental research doses (autism, schizophrenia). Up to 50 to 100 mg daily, under medical supervision.

How to achieve those doses in practice:

Raw broccoli sprouts. 30 to 60 g (1 to 2 oz) daily delivers roughly 5 to 60 mg depending on sprout age and freshness. Whole food, high bioavailability, inexpensive to grow at home.
Sprout powder with myrosinase. 1 to 2 g daily. Convenient and standardized, but quality varies; verify active myrosinase is present.
Glucoraphanin only. 200 to 400 mg daily. Shelf stable and convenient, but relies on gut bacteria for conversion (1 to 40% efficiency person to person); pair with mustard seed.
Glucoraphanin plus myrosinase. 100 to 200 mg daily. High bioavailability and consistent conversion. More expensive but preferred.

Fishtown Medicine

A 90-minute conversation with Dr. Ash. A written plan you can actually follow.

Start your intake

Flaws, side effects, and interactions

Being honest about the downsides is part of the job.

GI effects. High doses, particularly with raw sprouts, may cause bloating or gas. Start low and titrate up.
Goitrogen concern. Very high raw cruciferous intake (over 200 g daily) can worsen thyroid function in patients with iodine deficiency or hypothyroidism. Cooking reduces goitrogen activity but also reduces sulforaphane yield, so balance matters.
Active cancer paradox. While sulforaphane is protective for cancer prevention, constant Nrf2 activation in existing cancer cells may promote chemotherapy resistance. This is not a concern for prevention; it is a concern for patients in active treatment.
Drug interactions (key interactions):
- Thyroid hormone (levothyroxine): goitrogens may reduce iodine absorption; monitor TSH and ensure adequate iodine intake.
- Chemotherapy (select agents): may reduce efficacy via Nrf2 in cancer cells; discuss with oncologist and avoid during active treatment.
- Warfarin: cruciferous vegetables contain vitamin K; monitor INR. Sulforaphane itself is low risk at typical doses.
Pregnancy. Generally safe as part of normal dietary intake. High-dose supplements during pregnancy require physician guidance.

We look for: a glucoraphanin-plus-myrosinase supplement (Avmacol, BroccoMax with mustard seed extract, or a comparable standardized product), or raw 3-day-old broccoli sprouts eaten daily. Third-party testing for purity in any supplement form.
Worth considering alongside: NAC for glutathione substrate, quercetin or curcumin for synergistic Nrf2 activation. Garlic, onions, berries, and green tea broaden the antioxidant base and stack well with sulforaphane.
We dont lean on: cooked broccoli as a primary sulforaphane source (heat destroys myrosinase and collapses yield below 1 mg per 100 g), glucoraphanin-only supplements without mustard seed supplementation in patients with low gut microbiome conversion, or doses above 40 mg daily without a clinical reason.

Guidance from the Clinic

"Sulforaphane is one of the more interesting tools in the precision medicine toolkit because it works upstream. Instead of neutralizing one free radical at a time like vitamin C does, it signals your cells to build their own defense team for the next 72 hours. For my patients near I-95 or in industrial corridors, that Phase II detoxification support is directly relevant to what they are breathing every day. The key is solving the myrosinase problem, either through raw sprouts or the right supplement form."

Dr. Ash

Actionable Steps

A simple weekly sulforaphane plan.

Build a sprout habit. Buy 3-day-old broccoli sprouts at Whole Foods or Riverwards Produce, or grow them at home in a quart jar. Aim for about 2 ounces per day.
Eat them raw. Add to salads, omelets after cooking, or smoothies. Cooking destroys the conversion enzyme.
If you prefer a supplement, choose glucoraphanin plus myrosinase. Look for Avmacol or a similar standardized product.
Pair with detox foods. Garlic, onions, berries, and green tea stack well with sulforaphane and broaden the antioxidant base.
Disclose to your oncologist or endocrinologist if you are in active cancer treatment or managing thyroid disease before starting.

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Key Takeaways

Sulforaphane activates the Nrf2 pathway, switching on more than 200 antioxidant and detoxification genes for about 72 hours after each dose.
The richest source is 3-day-old raw broccoli sprouts (50 to 100 times more glucoraphanin than mature broccoli); the myrosinase enzyme is essential and destroyed by heat above 160 degrees Fahrenheit.
Practical dose is 10 to 40 mg per day (general prevention to metabolic support), from raw sprouts or a glucoraphanin-plus-myrosinase supplement.
Patients in active cancer treatment and those with significant thyroid disease should consult their physician before starting.
Sulforaphane pairs well with NAC for glutathione support, and is particularly relevant for urban patients with high environmental pollutant exposure.