Sulforaphane is a compound that forms when cruciferous vegetables like broccoli, cabbage, and cauliflower come into contact with certain proteins in your body or when they are otherwise “damaged,” such as when they’re chopped, cooked, or chewed.1
Sulforaphane starts as a substance called glucoraphanin. An enzyme called myrosinase turns it into sulforaphane. While this sulfur-rich chemical is generated when you prepare and eat cruciferous vegetables, it’s also available as a supplement.1
Sulforaphane is best known for its antioxidant and anti-inflammatory effects. These effects may help prevent cancer and cognitive decline, among other health benefits, though more research is needed.
Supplies Critical Nutrients
Every whole food that promotes sulforaphane production naturally supplies additional nutrients that likely support the health benefits of sulforaphane.
For example, in addition to generating sulforaphane, cruciferous vegetables like broccoli, Brussels sprouts, and kale are excellent sources of vitamin K, dietary fiber, and antioxidants that support health and longevity.2 Here’s how:
- Vitamin K contributes to bone health and regulates blood clotting in your body.3
- Eating enough fiber has been linked to a lower risk of conditions like cardiovascular disease, type 2 diabetes, and colon cancer.4
- Antioxidants are molecules that help reduce oxidative stress and its tissue damage in the body. Oxidative stress occurs when there are too many harmful molecules called free radicals and not enough antioxidants to stop them. The antioxidants in cruciferous vegetables have been linked to lower risks of cardiovascular conditions like hypertension (high blood pressure) and heart disease.1
While sulforaphane supplements that come as extracts usually deliver a much higher dose of sulforaphane than whole foods, they lack other nutrients, like dietary fiber, which likely provide additional benefits when you eat whole vegetables.
Has Anti-Inflammatory Properties
Sulforaphane works in several ways to reduce inflammation in your body. First, it activates a protein called Nrf2, which increases your body’s production of antioxidants.5 These antioxidants help protect cells from damage caused by inflammation, which can occur due to a variety of conditions.6
Sulforaphane also blocks the activity of NF-κB, a protein complex that activates genes responsible for creating inflammation in your body. By inhibiting NF-κB, sulforaphane reduces how many inflammatory molecules can be made in your body.7
May Prevent Cancer Cell Growth
So far, the strongest evidence for sulforaphane’s anticancer properties has been seen in prostate cancer. In one clinical trial, adults diagnosed with prostate cancer who took daily sulforaphane supplements for six months experienced an 86% increase in the amount of time it took for their prostate-specific antigen (PSA) levels to double in comparison to those who took a placebo.8
Since prostate cancer increases PSA levels, the study suggests that sulforaphane supplementation may help prevent or delay recurrences of prostate cancer. However, more research is needed.8
Observational studies (which can’t prove cause and effect but can show links between variables) have found connections between eating more cruciferous vegetables and having a lower risk of blood and liver cancers.9 The effect of sulforaphane supplementation is also being examined in clinical trials for its role in potentially reducing the risk of breast and lung cancers.10
How sulforaphane helps fight cancer is likely due to a combination of factors, including deactivating proteins that promote cancer cell growth and boosting the actions of proteins that combat cancer cell growth in your body.
Of course, foods like Brussels sprouts and radishes that cause sulforaphane production are usually packed with additional nutrients that likely support the molecule’s cancer-fighting properties.
May Lower Blood Sugar
One study found that people with type 2 diabetes experienced a significant reduction in their blood sugar levels when they took a broccoli sprout supplement every day for 12 weeks.11
Despite these promising findings, researchers caution that more studies are needed before broccoli extracts are recommended as a standard therapy for people with type 2 diabetes.
Might Slow Cognitive Decline and Aging
Aging coincides with neurodegeneration, a process in which brain and central nervous system cells begin losing functionality. When this happens, conditions like Alzheimer’s disease and Parkinson’s disease can occur.12
While there’s no cure for these diseases, researchers are studying how different plant chemicals, including sulforaphane, can help delay aging and its associated neurodegenerative diseases. Sulforaphane likely protects neurons thanks to its ability to activate powerful antioxidant pathways in the body.13
While early research is promising, more research is needed in humans before sulforaphane supplements are recommended for anti-aging purposes. For now, regularly include cruciferous vegetables in your diet for brain (and other) health benefits.
Foods With Sulforaphane
Cruciferous vegetables don’t contain sulforaphane: consuming them causes the molecule to be produced. Here’s exactly how sulforaphane is generated:1
- Cruciferous vegetables contain a compound called glucoraphanin.
- Glucoraphanin is a precursor to sulforaphane. Precursors are substances that are needed to make new products.
- Sulforaphane is produced when glucoraphanin comes into contact with a protein called myrosinase. This can happen during chewing or further down the digestive tract.
Foods that contain sulforaphane precursors, called glucosinolates, include:114
- Broccoli (particularly broccoli sprouts, which are younger than the standard mature broccoli found in the grocery store)
- Cabbage
- Cauliflower
- Bok choy
- Radish
- Kale
- Turnips
- Arugula
- Kohlrabi
- Watercress
- Brussels sprouts
How much sulforaphane you absorb from these foods depends on their preparation. This is because the enzyme myrosinase in cruciferous vegetables is deactivated by heat.
Since you need myrosinase to create sulforaphane, you won’t absorb as much sulforaphane from thoroughly cooked cruciferous vegetables as you will from raw ones. Fortunately, myrosinase is naturally present in the colon, so even cooked crucifers can lead to sulforaphane production in the body.
To avoid damaging the enzyme in the vegetables, try lightly steaming your cabbage or broccoli for three minutes.15 Avoid boiling, microwaving, or pressure cooking, as these preparations may eliminate up to 90% of the vegetables’ glucosinolates.16
Taking Sulforaphane Supplements
Taking a supplement that supports sulforaphane production isn’t the same as eating broccoli with your dinner. Supplements tend to contain higher doses of active ingredients compared to the amount naturally found in food.
The list of potential benefits of sulforaphane supplementation is lengthy. Early research indicates that broccoli sprout extracts may improve asthma and hay fever symptoms. Unfortunately, the results are not yet significant or long-lasting.1
Most clinical studies of sulforaphane supplementation have been short in duration, so it’s unclear if the ingredient is safe to take for longer than six months. Doses of sulforaphane used in clinical settings have ranged from 35-180 milligrams (mg) per day.1
Remember that supplements are minimally regulated by the Food and Drug Administration (FDA) and can interact with other dietary supplements, health conditions, and medications. Always speak with your healthcare provider before starting any new supplements to ensure they’re safe for you.
What’s the Difference Between Sulforaphane and DIM?
Like sulforaphane, DIM (diindolylmethane) is a different chemical created in the body when cruciferous vegetables are digested. Research on the benefits of DIM supplementation is ongoing, but early findings suggest that DIM may improve symptoms caused by excess estrogen and help treat breast cancer.17
Risks and Side Effects of Sulforaphane
Just because sulforaphane is generated from whole foods doesn’t mean it can’t pose risks or side effects. Possible side effects of sulforaphane will depend on how it’s consumed and your health conditions.
Here are a few groups that might want to experience adverse reactions to sulforaphane foods and supplements:18
- People with irritable bowel syndrome (IBS): Eating large quantities of cruciferous vegetables (particularly when raw) can cause digestive discomfort for some people. Those with IBS may be particularly sensitive to cruciferous vegetables since they are high in fermentable carbohydrates that commonly cause stomach upset, heartburn, gas, and bloating.
- People with iodine deficiencies: Eating large quantities of raw cruciferous vegetables can compromise thyroid function and potentially lead to hypothyroidism (underactive thyroid) in those with an iodine deficiency (which is rare in the United States but common in other parts of the world).
- People with autism spectrum disorder (ASD) or a history of seizures: One study that tested the effects of sulforaphane supplementation in people with ASD reported that two participants experienced seizures after taking sulforaphane. However, it’s unclear if the seizures were a direct result of the supplement.19 Anyone diagnosed with ASD or a history of seizures should speak to their healthcare provider before incorporating a sulforaphane supplement.
Information about optimal dosing for sulforaphane supplements is also limited. There’s not enough research to determine what amount may lead to adverse effects or symptoms of overdose.
A Quick Review
Sulforaphane is a compound naturally produced when you eat cruciferous vegetables like broccoli, cauliflower, and Brussels sprouts. Regularly eating sulforaphane-producing foods can promote antioxidant and anti-inflammatory benefits such as lowering blood sugar, reducing cancer risk, and delaying age-related cognitive decline.
Research on the safety and benefits of sulforaphane supplements—which are usually made from broccoli sprout extract—is ongoing. More research is needed to confirm the benefits of sulforaphane. For now, work on regularly adding cruciferous vegetables to your plate for a healthy dose of sulforaphane, vitamin K, dietary fiber, and antioxidants.
