Sulforaphane
A broccoli sprout compound with intriguing early research — and big differences in what products deliver.
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What it is
Sulforaphane is a sulfur compound that forms when broccoli and other cruciferous vegetables are chopped or chewed, as a precursor called glucoraphanin meets the plant enzyme myrosinase. Broccoli sprouts are an especially concentrated source of glucoraphanin.
How it works
Sulforaphane activates Nrf2, a master switch inside cells that turns on a suite of protective genes, including antioxidant and detoxification (phase 2) enzymes. Rather than acting mainly as an antioxidant itself, it prompts cells to strengthen their own defenses. This is well documented in lab studies; how strongly it happens in people at supplement doses, and whether it produces meaningful health benefits, is still being studied.
What it's been studied for
Commonly taken for cellular antioxidant and detoxification support, and increasingly for blood sugar, brain, and healthy-aging goals.
What the evidence shows
Early. Small human trials have tested broccoli sprout preparations for blood sugar in type 2 diabetes, excretion of airborne pollutants, and autism-related behaviors, with intriguing but inconsistent results, and much of the rest comes from lab and animal studies. The key limitations are small, short trials and wide differences in how much sulforaphane different products actually deliver.
Who should consider it
People interested in cruciferous vegetable compounds who understand the research is early might reasonably try it — though eating broccoli sprouts or lightly cooked broccoli is a solid starting point. Those expecting a proven fix for blood sugar, brain health, or detox are likely to be disappointed by the current evidence. Anyone considering it for a child or a medical condition should do so with a provider's guidance.
Amounts commonly studied
Human studies used broccoli sprout preparations delivering widely varying amounts, commonly from tens of micromoles up to about 150 micromoles of sulforaphane per day, or larger amounts of glucoraphanin, which only partly converts.
How to take it
Studies typically used daily broccoli sprout preparations for several weeks to a few months, often with food to reduce stomach upset. Because products differ so much, choose one that reports how much sulforaphane it provides rather than only glucoraphanin. Talk to your provider first if you're pregnant, undergoing chemotherapy, or managing a thyroid condition.
Forms & absorption
Products come as glucoraphanin alone (which relies on gut bacteria for limited, inconsistent conversion), glucoraphanin paired with active myrosinase (better conversion), or stabilized sulforaphane. Sulforaphane itself is unstable, so actual yield varies by product — labels that state the sulforaphane delivered are more informative than glucoraphanin content alone.
Food sources
Broccoli sprouts are by far the richest source, followed by raw or lightly steamed broccoli, Brussels sprouts, cabbage, cauliflower, kale, and other cruciferous vegetables; adding mustard seed powder to cooked broccoli can restore some conversion.
Safety & interactions
Generally well tolerated in short studies; gas, bloating, nausea, and heartburn are the most common complaints. Long-term safety isn't established and data in pregnancy and breastfeeding are lacking, so stick to food sources during those times. People with thyroid conditions, those undergoing chemotherapy, and anyone on multiple medicines should talk to their provider first, since possible effects on thyroid function and drug-metabolizing enzymes are largely theoretical but not fully understood.
Myths & what it won't do
Myth: all broccoli sprout supplements provide the same sulforaphane. Reality: many contain only glucoraphanin, and without active myrosinase, conversion can be low and vary widely between people. Myth: well-cooked broccoli gives you just as much. Reality: cooking destroys myrosinase, so well-cooked broccoli yields much less — chewing raw sprouts, light steaming, or adding a pinch of mustard seed powder helps.
Common questions
- Is it better to eat broccoli sprouts or take a supplement?
- Fresh broccoli sprouts chewed well are an excellent source and come with fiber and other nutrients. Supplements offer a consistent dose, but only if the product actually delivers sulforaphane — quality varies widely.
- What does 'with myrosinase' on the label mean?
- Myrosinase is the plant enzyme that converts glucoraphanin into sulforaphane. Products that include active myrosinase tend to yield much more sulforaphane than glucoraphanin-only products, which depend on your gut bacteria.
- Does sulforaphane detox the body?
- It switches on the body's own detoxification enzymes, and one trial found a broccoli sprout drink increased excretion of certain air pollutants. That's interesting, but it's not a proven 'detox,' and your liver and kidneys already do most of this work.
The amounts listed here are what published research has used — not a prescription or a recommended dose for you. Confirm anything you plan to take with your own healthcare provider, especially if you take medications, are pregnant or nursing, or have a health condition.
Related goals
Research on Sulforaphane
Recommendations on this page are informed by published research. This is educational information, not medical advice.
- Axelsson AS, Tubbs E, Mecham B, et al. Sulforaphane reduces hepatic glucose production and improves glucose control in patients with type 2 diabetes. Sci Transl Med. 2017;9(394):eaah4477. View study →Note: Mostly lab and animal work; in a small trial, broccoli sprout extract lowered fasting glucose and HbA1c in obese people with poorly controlled type 2 diabetes.
- Fahey JW, Holtzclaw WD, Wehage SL, et al. Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase. PLoS One. 2015;10(11):e0140963. View study →Note: Sulforaphane was about 3 to 4 times more available when the product included active myrosinase.