Sulforaphane
The most potent natural Nrf2 activator known — switches on the body's master detoxification and antioxidant defence program. Derived from broccoli sprouts.
Strong mechanism evidence (Nrf2 activation, detox enzyme upregulation). Moderate human evidence: improved liver detoxification, reduced airway inflammation, lowered oxidative stress markers, modest blood pressure reduction, and an autism trial showing symptom improvement (Singh et al.). Cancer prevention is plausible but hard to prove. Effects: 2–8 weeks.
Sulforaphane is an isothiocyanate produced when you chew or chop cruciferous vegetables — particularly broccoli sprouts, which contain 10–100x more of its precursor (glucoraphanin) than mature broccoli. It activates Nrf2 (Nuclear Factor Erythroid 2), the master switch for the body's Phase II detoxification enzymes, antioxidant defences, and anti-inflammatory pathways. Effects are broad: improved detoxification of carcinogens, reduced oxidative stress, modulation of inflammation, and potential anti-cancer effects (particularly against breast, prostate, and bladder cancers). Sulforaphane is one of the most-studied phytochemicals in cancer prevention research — most prominently championed by Dr. Jed Fahey at Johns Hopkins.
Key studies
- Bioavailability of sulforaphane from glucoraphanin-rich extracts with active myrosinase (Nutrients, 2019) — Why the enzyme is the whole question. Measuring urinary metabolites in humans after a broccoli seed-and-sprout extract WITH active myrosinase, conversion of glucoraphanin to sulforaphane ran far higher than the roughly 10% typical of gut-bacteria conversion alone. Buy the enzyme, or eat the sprouts.
- Form
- The one thing that decides whether a sulforaphane product works: sulforaphane itself is unstable, so supplements sell you glucoraphanin, its precursor. Converting that to sulforaphane needs the enzyme myrosinase — and if the product doesn't supply active myrosinase, you're relying on your own gut bacteria to do it, which is inefficient and varies enormously between people. So: buy a product that states ACTIVE MYROSINASE, or eat fresh sprouts, which bring their own. Options: broccoli seed and sprout extract with added myrosinase (Avmacol is the brand used in the published human trials, where urinary metabolites showed ~40–50% conversion; Life Extension's Optimized Broccoli also includes it). Glucoraphanin-only extracts such as BroccoMax rely on gut conversion. Fresh broccoli sprouts, 3–7 days old, are the original source and cheap to grow at home.
- Dose
- 10–40 mg/day of active sulforaphane from extracts, or ~100 g (half a cup) of fresh broccoli sprouts daily. Compare products on stated sulforaphane yield or glucoraphanin content plus myrosinase — not on milligrams of 'broccoli extract', which tells you nothing about how much you'll actually absorb.
- Timing
- Anytime. With food generally fine. Heat destroys sulforaphane — eat sprouts raw or steam briefly.
- Schedule
- Daily.
- Side effects
- Generally well-tolerated. Mild GI upset, gas (from cruciferous compounds). Body / breath odor in some.
- Interactions
- Acetaminophen — sulforaphane induces enzymes that may alter metabolism. Anticoagulants (broccoli is K-rich — caution if eating large amounts of sprouts on warfarin).
- Contraindications
- Hypothyroidism (raw cruciferous in very large amounts can be goitrogenic — cooking neutralises this; supplements are generally fine at standard doses). Active malabsorption.
- Lab markers
- Not standard. Functional / research markers: GSH (glutathione), 8-OHdG, urinary sulforaphane metabolites.
- Food sources
- Broccoli sprouts (extraordinary concentration), broccoli, brussels sprouts, cauliflower, kale, cabbage, bok choy, watercress, mustard greens, daikon radish. Chewing thoroughly activates the conversion enzyme — bolting them down whole reduces yield.
Pairs with
Glucoraphanin + myrosinase — needed together for conversion. Curcumin, quercetin, EGCG (polyphenol Nrf2 stack). DIM, I3C (synergistic estrogen metabolism support).
Where to buy
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within Polyphenols & antioxidants