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 are chopped, cooked or chewed.
Sulforaphane starts with a substance called glucoraphanin. An enzyme called myrosinase converts it into sulforaphane. Although this sulfur-rich chemical is generated when you prepare and eat cruciferous vegetables, it is also available in supplement form.
Sulforaphane is best known for its antioxidant and anti-inflammatory effects. These effects could help prevent cancer and cognitive decline, among other health benefits, although more research is needed.
Each whole food that supports sulforaphane production naturally provides additional nutrients that may 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 promote health and longevity. Here’s how:
- Vitamin K contributes to bone health and regulates blood clotting in your body.
- Eating enough fiber has been linked to a lower risk of diseases such as cardiovascular disease, type 2 diabetes and colon cancer.
- Antioxidants are molecules that help reduce oxidative stress and its damage to body tissues. 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 diseases like hypertension (high blood pressure) and heart disease.
Although sulforaphane supplements presented as extracts generally provide a much higher dose of sulforaphane than whole foods, they lack other nutrients, like dietary fiber, which likely provide additional benefits when eating whole vegetables. .
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. These antioxidants help protect cells from damage caused by inflammation, which can occur due to various conditions.
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 the number of inflammatory molecules that can be produced in your body.
So far, the strongest evidence for sulforaphane’s anticancer properties has been seen in prostate cancer. In a clinical trial, adults with prostate cancer who took sulforaphane supplements daily for six months saw an 86% increase in the time it took for their prostate-specific antigen (PSA) levels to double compared to to those who took a placebo. .
Since prostate cancer increases PSA levels, the study suggests that sulforaphane supplementation could help prevent or delay prostate cancer recurrences. However, further research is needed.
Observational studies (which cannot prove cause and effect but can show connections between variables) have linked increased consumption of cruciferous vegetables to a lower risk of blood and liver cancer. The effect of sulforaphane supplementation is also being examined in clinical trials for its role in potentially reducing the risk of breast and lung cancer.
How sulforaphane helps fight cancer is likely due to a combination of factors, including disabling proteins that promote the growth of cancer cells and increasing the actions of proteins that fight the growth of cancer cells in your body.
Of course, foods like Brussels sprouts and radishes that cause sulforaphane production usually contain additional nutrients that may boost the molecule’s anti-cancer properties.
One study found that people with type 2 diabetes had a significant reduction in their blood sugar levels when they took a broccoli sprout supplement every day for 12 weeks.
Despite these promising results, researchers caution that additional studies are needed before broccoli extracts are recommended as a standard treatment for people with type 2 diabetes.
Aging coincides with neurodegeneration, a process in which cells in the brain and central nervous system begin to lose functionality. When this happens, diseases such as Alzheimer’s disease and Parkinson’s disease can occur.
Although there is no cure for these diseases, researchers are studying how different plant chemicals, including sulforaphane, can help delay aging and associated neurodegenerative diseases. Sulforaphane likely protects neurons through its ability to activate powerful antioxidant pathways in the body.
Although early research is promising, more research is needed in humans before sulforaphane supplements are recommended for anti-aging purposes. For now, include cruciferous vegetables in your diet regularly for brain (and other) health benefits.
Cruciferous vegetables do not contain sulforaphane: their consumption causes the production of the molecule. Here is exactly how sulforaphane is generated:
- Cruciferous vegetables contain a compound called glucoraphanin.
- Glucoraphanin is a precursor of sulforaphane. Precursors are substances necessary for the manufacture of 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:
- Broccoli (especially broccoli sprouts, which are younger than the standard ripe broccoli found at the grocery store)
- Cabbage
- Cauliflower
- Bok choy
- Radish
- kale
- Turnips
- Rocket
- Kohlrabi
- Cress
- Brussels sprouts
The amount of sulforaphane you get from these foods depends on how they are prepared. Indeed, the myrosinase enzyme present in cruciferous vegetables is deactivated by heat.
Since you need myrosinase to create sulforaphane, you won’t absorb as much sulforaphane from well-cooked cruciferous vegetables as you will from raw vegetables. Fortunately, myrosinase occurs naturally in the colon, so even cooked cruciferous vegetables can cause the body to produce sulforaphane.
To avoid damaging the enzyme in vegetables, try lightly steaming your cabbage or broccoli for three minutes. Avoid boiling, microwaving, or pressure cooking, as these preparations can remove up to 90% of glucosinolates from vegetables.
Taking a supplement that supports sulforaphane production is not the same as eating broccoli with your dinner. Supplements tend to contain higher doses of active ingredients than the amount naturally found in foods.
The list of potential benefits of sulforaphane supplementation is long. Early research indicates that broccoli sprout extracts may improve symptoms of asthma and hay fever. Unfortunately, the results are not yet significant or lasting.
Most clinical studies of sulforaphane supplementation have been short-term, so it is unclear whether the ingredient is safe to take for more than six months. Doses of sulforaphane used in clinical settings range from 35 to 180 milligrams (mg) per day.
Keep in mind that supplements are lightly regulated by the Food and Drug Administration (FDA) and may interact with other dietary supplements, health conditions, and medications. Always speak with your healthcare professional before starting any new supplement to make sure it is safe for you.
Just because sulforaphane is generated from whole foods doesn’t mean it can’t have risks or side effects. The possible side effects of sulforaphane will depend on how it is consumed and your health.
Here are some groups who may want to experience adverse reactions to sulforaphane foods and supplements:
- People with irritable bowel syndrome (ICS): Eating large amounts of cruciferous vegetables (especially raw) can cause digestive upset in some people. People with IBS may be particularly sensitive to cruciferous vegetables because they are high in fermentable carbohydrates that commonly cause stomach upset, heartburn, gas, and bloating.
- People with iodine deficiency: Eating large amounts of raw cruciferous vegetables can compromise thyroid function and potentially lead to hypothyroidism (underactive thyroid) in people with iodine deficiency (which is rare in the United States but common in other parts of the world).
- People with autism spectrum disorders (ASD) or history of seizures: A study that tested the effects of sulforaphane supplementation in people with ASD reported that two participants had seizures after taking sulforaphane. However, it is unclear whether the seizures were a direct result of the supplement. Anyone diagnosed with ASD or a history of seizures should talk to their doctor before incorporating a sulforaphane supplement.
Information on the optimal dosage of sulforaphane supplements is also limited. There is not enough research to determine how much can cause side effects or overdose symptoms.
Sulforaphane is a compound produced naturally when you eat cruciferous vegetables like broccoli, cauliflower, and Brussels sprouts. Regular consumption of sulforaphane-producing foods may promote antioxidant and anti-inflammatory benefits such as lowering blood sugar, reducing cancer risk, and delaying age-related cognitive decline.
Research into the safety and benefits of sulforaphane supplements, typically made from broccoli sprout extract, is ongoing. More research is needed to confirm the benefits of sulforaphane. For now, work on adding cruciferous vegetables to your plate regularly for a healthy dose of sulforaphane, vitamin K, dietary fiber and antioxidants.