Sulforaphane: Benefits, Safety, and Nutrition

By Brittany Poulson, MDA, RDN, CD, CDCES 
Medically reviewed by Erika Prouty, PharmD

https://www.verywellhealth.com/sulforaphane-5083128


Sulforaphane is a natural plant compound derived from cruciferous vegetables, such as broccoli and Brussels sprouts.

It is known for its antioxidant, antimicrobial, and anti-inflammatory properties. As such, some research has looked at its potential health benefits, including cancer prevention and heart and kidney health.

In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. When choosing a supplement, look for independently tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist. 

What Is Sulforaphane?

Sulforaphane is a natural plant compound derived from cruciferous vegetables, such as broccoli, cauliflower, and kale.Sulforaphane in cruciferous vegetables is present in a stored, inactive form called glucoraphanin. Glucoraphanin is converted to sulforaphane’s active form by the enzyme myrosinase. This activation is triggered by chopping or chewing but can also be produced in the gut by certain bacteria.
Researchers have studied sulforaphane for its potential health effects on various conditions, including cancer prevention, diabetes, heart disease, kidney health, and autism.

May Help Prevent Cancer

Sulforaphane has chemoprotective properties.² That means it helps stop carcinogens (cancer-causing substances) from impacting the body. In addition, it’s anti-inflammatory. Inflammation can play a role in some types of tumor formation. Sulforaphane may benefit cancer prevention.
A 2020 randomized study of adults with pancreatic cancer undergoing chemotherapy was conducted. The researchers reported the survival rate was higher in the treatment group than in the placebo group at six months. However, the results were not statistically significant.
Research published in 2019 studied the effects of sulforaphane supplementation on prostate cancer progression. Participants ate broccoli soup with glucoraphanin. The test group had a dose-dependent reduction in prostate cancer progression.
In addition, a 2016 study looked at the association between cruciferous vegetable intake and specific tumor biomarkers. Researchers evaluated 54 people scheduled for breast biopsies after abnormal mammogram findings.
Cruciferous vegetable intake was associated with decreased cell growth in breast tissue. However, other compounds in broccoli may have contributed to these findings.

May Help Autism Symptoms

Some studies have reported sulforaphane increased improvements in behavior, communication, and social interaction.
A 2024 randomized trial in collaboration with researchers from China, Johns Hopkins, Columbia University, and more reported some improvements in autistic children who were given sulforaphane. The treatment was also reportedly well tolerated. However, the researchers suggested further study was needed given the differences between clinician and caregiver scores.

On the other hand, a study published in 2023 reported a lack of clinically significant changes using sulforaphane for children with autism.

Further research is needed.

May Improve Cardiovascular Disease

Because oxidative stress and inflammation are markers in cardiovascular disease, and sulforaphanes have antioxidant and anti-inflammatory properties, researchers have looked at their potential role in protecting against heart disease.

A 2015 paper reviewed how sulforaphane might be protective against cardiovascular disease.¹⁰ Clinical studies and animal experiments demonstrated that sulforaphane is potentially protective against heart diseases, including hypertension and atherosclerosis.

Evidence for this use is limited. Therefore, more research is needed.

May Help Insulin Resistance in Diabetes

Sulforaphane’s role in maintaining healthy cells and genes has prompted some researchers to look at its potential role in diabetes and insulin resistance (when your body doesn’t respond normally to the hormone insulin) and diabetes.

A 2012 randomized, double-blind study examined the effects of broccoli sprouts on insulin resistance in people with type 2 diabetes.¹² Researchers analyzed glucose and insulin levels in 63 people who received a placebo or broccoli sprout powder for four weeks. Results showed a significant decrease in serum insulin concentration and resistance in those receiving 10 grams per day of broccoli sprouts.

May Boost Kidney Health

Preclinical research from 2023 suggests that sulforaphane may benefit kidney health. Research indicates sulforaphane may:

• Increase creatinine clearance (a measure of how well the kidneys filter creatinine out of the bloodstream).
• Decrease creatinine and urea levels (indicators of kidney function)
• Improve kidney lesions
• Decrease markers of kidney injury

The bulk of these studies were in animal models, so further research in humans is warranted.

Other Potential Uses

In addition to the above, people also use sulforaphane for other health conditions, though there are few quality human studies on these topics. These include: 

• Constipation
• Sun damage to the skin
• Osteoporosis
• Neurological diseases
• Obesity

What Are the Side Effects of Sulforaphane?

Your healthcare provider may recommend sulforaphane to reduce your risk of cancer, heart disease, or diabetes. However, consuming a supplement like sulforaphane may have potential side effects. These may be common or severe.

Common Side Effects

Sulforaphane is safe when consumed in plant forms, such as kale or broccoli. In supplement form, sulforaphane has minor, if any, side effects. The main side effects include digestive problems, such as gas and a bad aftertaste. (Broccoli in particular is likely to cause gas.)

Severe Side Effects

Some animal research indicates that high doses of sulforaphane could cause the following side effects associated with toxicity:

• Sedation
• Hypothermia (low body temperature)
• Impaired motor coordination
• Decreased skeletal muscle strength
• Death

Though sulforaphane seems to be well tolerated with minimal side effects, there is insufficient quality research to know if it is safe to take by mouth as a medicine, especially in high doses and for long periods.

Precautions

Sulforaphane is safe during pregnancy and breastfeeding when eaten in whole food form, such as broccoli. However, whether it’s safe when taken as a supplement during pregnancy and breastfeeding is unknown. Therefore, you should avoid taking the supplement if you are pregnant or breastfeeding or consult with a healthcare provider first.

In addition, sulforaphane may interfere with some anti-seizure medications, including Tegretol (carbamazepine).

Dosage: How Much Sulforaphane Should I Take?

There are no daily intake recommendations for sulforaphane, and supplement brands vary widely in how much they suggest taking.

Some animal studies have used a wide range of dosages, including 3–10 µmol/kg to >100 µmol/kg.

Although there is a wide availability of sulforaphane in supplemental form, more research is needed to determine the ideal dose, safety, and effectiveness. Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

What Happens if I Take Too Much Sulforaphane?

While there is no established upper limit for sulforaphane, some research has found evidence of toxicity at doses of 150 to 300 milligrams/kilogram of body weight (mg/kg).

Seek immediate medical care if you experience any of the severe side effects listed above.

Sources of Sulforaphane

Sulforaphane is widely available through cruciferous food sources. In addition, you can take it as a supplement.

Food Sources of Sulforaphane

Cruciferous vegetables are well known for their sulforaphane content, including:

• Broccoli
• Broccoli sprouts
• Kale
• Cauliflower
• Brussels sprouts
• Cabbage
• Bok choy
• Watercress
• Collard greens
• Turnips

Does cooking foods change their sulforaphane content?

Cooking foods seems to decrease the amount of sulforaphane in cruciferous vegetables, with raw vegetables having the highest levels of sulforaphane. According to one study, raw broccoli has 10 times more sulforaphane than cooked broccoli.

If you prefer your cruciferous vegetables cooked, steaming might have the least effect on sulforaphane levels. A study found that steaming broccoli for one to three minutes may be the best way to get the most sulforaphane when cooking, compared to microwaving and boiling.

Sulforaphane Supplements

Sulforaphane supplements are available in various forms, including:

• Tablets
• Capsules
• Powder
• Liquid

They are often made from broccoli, broccoli seeds, or broccoli sprouts extract. Some sulforaphane supplement manufacturers also advertise their products as combined with myrosinase enzymes for enhanced absorption.

How to Store Sulforaphane

Store sulforaphane in a cool, dry place. Keep sulforaphane away from direct sunlight. Discard after one year or as indicated on the packaging.

Summary

Sulforaphane is a natural plant compound found in cruciferous vegetables and supplements. It is known for its antioxidant, antimicrobial, and anti-inflammatory properties. Some people take sulforaphane for health reasons, such as lowering their risk of cancer, heart disease, kidney conditions, and diabetes, or to treat moderate to severe autism symptoms. There is some evidence to support those uses, but the research is limited.