Sulforaphane and Broccoli Sprout Extract: What Studies Show

What is sulforaphane?

Sulforaphane belongs to a group of compounds called isothiocyanates. Cruciferous vegetables such as broccoli, cabbage, kale and Brussels sprouts do not contain much of it ready-made. Instead they hold sulfur-containing precursors called glucosinolates. Broccoli's main one is glucoraphanin, the parent of sulforaphane (Linus Pauling Institute).

The conversion depends on an enzyme. In an intact plant, myrosinase sits in a separate compartment from glucoraphanin. Chopping, blending or chewing breaks the cells open, the enzyme reaches the glucoraphanin, and sulforaphane forms. That reaction is also behind the sharp, slightly bitter bite of raw crucifers (Linus Pauling Institute).

If you are searching in Spanish for "sulforafano: qué es y para qué sirve," the short version is this: it is a broccoli-derived compound being studied for how it turns on the body's own defense and detox enzymes. It is not a nutrient you need, and it is not an approved treatment for anything.

Why broccoli sprouts have so much more

In 1997, researchers at Johns Hopkins reported that 3-day-old sprouts of certain broccoli and cauliflower varieties contained 10 to 100 times more glucoraphanin than the grown plants (Fahey, Zhang and Talalay, PNAS, 1997). The seed's supply stays roughly the same as it sprouts, so a tiny sprout packs it into far less weight. The same paper found that many broccoli sprouts contain very little of the indole glucosinolates that dominate in mature broccoli.

The Linus Pauling Institute notes that some stores sell sprouts certified to supply at least 73 mg of glucoraphanin per 1-ounce serving. For comparison, it lists about 27 mg of total glucosinolates (all types combined, not just glucoraphanin) in half a cup of chopped raw broccoli.

Does cooking destroy sulforaphane?

Cooking does not destroy glucoraphanin, but it does knock out myrosinase. Without the plant enzyme, conversion falls to your gut bacteria, which can make some sulforaphane in the colon, but less of it and less predictably (Linus Pauling Institute). Light steaming for under five minutes keeps part of the enzyme working. In practice:

• Eat some broccoli or sprouts raw, chopped or well chewed.
• Steam briefly rather than boiling for a long time.

Broccoli extract supplements: which type is which?

"Broccoli extract" on a label can mean several different things. How much sulforaphane you actually absorb depends heavily on which one you buy.

When comparing labels, look for the amount of glucoraphanin or sulforaphane per serving and whether myrosinase is included, not just milligrams of "broccoli extract."

What studies show: para qué sirve el sulforafano

Most of the excitement comes from lab and animal work. Sulforaphane activates Nrf2, a switch inside cells that turns on genes for protective enzymes. These "phase 2" enzymes help neutralize reactive molecules and prepare some toxins for removal (MSKCC). Human research is smaller and more mixed:

• Airborne pollutants: in a 12-week randomized trial, 291 adults in Qidong, China, a region with heavy air pollution, drank a broccoli sprout beverage daily or a placebo. The sprout group excreted 61% more of a benzene breakdown product and 23% more of an acrolein product, a sign their bodies were clearing these pollutants faster (Egner et al., Cancer Prevention Research, 2014). No change was seen for a third pollutant, crotonaldehyde.
• Autism: a small 2014 trial gave 44 young men (ages 13 to 27) with autism sulforaphane from broccoli sprout extract or placebo for 18 weeks. Caregiver-rated behavior scores improved by 34% on one scale and 17% on another in the sulforaphane group, then drifted back after it was stopped (Singh et al., PNAS, 2014). Later trials in children were less clear. A 57-child US study missed its main goal but saw improvement on a secondary behavior scale (Zimmerman et al., Molecular Autism, 2021), and a Czech study of children aged 3 to 7 found no significant change (Magner et al., Nutrients, 2023). A 2025 meta-analysis of six trials found modest improvements and urged caution (Wang et al., EXCLI Journal, 2025).
• Airway and lungs: broccoli sprout homogenate raised protective enzymes in the upper airway within hours, but a four-week trial in people with COPD found no such effect in lung cells (Linus Pauling Institute).
• Stomach: broccoli sprouts eased H. pylori gastritis in some studies but did not clear the infection, and adding sulforaphane to standard antibiotic therapy did not help (MSKCC).
• Cancer: diets high in cruciferous vegetables are linked with lower cancer risk, but the Linus Pauling Institute concludes there is not enough evidence that isothiocyanates themselves are the reason.

Sulforaphane research is promising but early. It is a reason to eat more crucifers, not a proven remedy. For a broader look at foods and supplements people use for everyday defenses, see our immune support guide.

How sulforaphane differs from DIM and I3C

Indole-3-carbinol (I3C) comes from a different broccoli glucosinolate, glucobrassicin, and stomach acid turns it into DIM (diindolylmethane). Both are studied mainly for how they shift estrogen metabolism, and the Linus Pauling Institute notes some experts urge caution with them until risks and benefits are clearer. They are not substitutes for sulforaphane.

Is sulforaphane safe? Side effects and cautions

Sulforaphane from food is part of a normal diet, and the Linus Pauling Institute reports no serious adverse effects of isothiocyanates in people. Supplements are generally well tolerated in trials (MSKCC). Things to know:

• Stomach upset: nausea, vomiting and other digestive complaints were reported in a feasibility study of high-dose broccoli sprout capsules in people with advanced pancreatic cancer (MSKCC). In the 2021 autism trial, the few side effects included trouble sleeping, irritability and dislike of the taste or smell.
• Thyroid: some breakdown products of cruciferous plants can interfere with iodine use, and very large intakes caused low thyroid function in animals. In people, risk appears tied to iodine deficiency (Linus Pauling Institute). A 12-week trial in 45 women drinking a broccoli sprout beverage found no change in thyroid hormones or thyroid antibodies (Chartoumpekis et al., Food and Chemical Toxicology, 2019). If you have a thyroid condition, mention supplements to your doctor.
• Medications: isothiocyanates are not known to interact with drugs, but they can affect liver enzymes that process many medicines, so a theoretical risk exists (Linus Pauling Institute).
• Pregnancy and breastfeeding: there is no safety information on concentrated supplements, so stick to food sources.

Since gut bacteria do part of the conversion work, your microbiome may influence how much sulforaphane you make from cooked crucifers. Our probiotics and prebiotics guide covers the gut side of the story.

Find it at William's

We carry a few ways to add these cruciferous compounds, and they are not interchangeable:

• Source Naturals broccoli sprouts extract, 250 mg, 60 tablets: a broccoli sprout extract whose label lists 2,000 mcg of sulforaphane per tablet.
• Life Extension Optimized Broccoli and Cruciferous Blend, 30 enteric-coated tablets: a dual-layer formula that its maker describes in terms of glucoraphanin and myrosinase. Check the supplement facts panel for exact amounts.
• Now DIM 200 with calcium D-glucarate, 90 veg capsules: DIM rather than sulforaphane, for shoppers interested in the indole side of cruciferous research.

Fresh broccoli, cabbage and other crucifers remain the easiest everyday source. If you like pungent foods, our garlic extract guide covers another sulfur-rich plant food.

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