What Is Sulforaphane?

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 and is studied for its health benefits, such as for cancer prevention, heart health, and as a treatment for autism.

Sulforaphane in cruciferous vegetables occurs in a stored, inactive form as glucoraphanin. Glucoraphanin is converted to sulforaphane by the enzyme myrosinase to its active form. Myrosinase in the plant is activated by chopping or chewing, but can also be produced in the gut by certain bacteria.

What Is Sulforaphane Used For?

Sulforaphane has been studied for its potential health effects on a variety of conditions. However, more high-quality human research is needed to fully understand the extent of these effects.

Cancer

Research has shown the potential anticancer benefits of sulforaphane in various studies. There is a lot of research done in vitro and animal studies, however, and larger human studies are necessary in order to understand its full potential.

One randomized, double-blinded study, published in 2020, looked at 40 adults in palliative chemotherapy with pancreatic cancer. The researchers reported that—though not statistically significant—compared to those in the placebo group, the survival rate was higher in the treatment group during the first six months after intake and that supplementation did not severely impact their self-care and overall abilities.

Another study published in 2014 reported on the effects of sulforaphane supplementation in 20 people with recurrent prostate cancer. The study did not reveal statistically significant results, however they found that sulforaphane treatment was safe with no adverse side effects.

Research published in 2019 studied the effects of sulforaphane supplementation on prostate cancer progression. Forty-nine subjects were put into two groups, a control group and a test group, and were given soup made with standard broccoli or broccoli with enhanced concentrations of glucoraphanin, respectively.

After 12 months of eating a portion of broccoli soup each week, an inverse dose-dependent association was observed between the test group and prostate cancer progression.

A 2016 study looked at the association between cruciferous vegetable intake and certain tumor biomarkers among 54 people scheduled for breast biopsies after abnormal mammogram findings. The study found that total cruciferous vegetable intake was associated with decreased cell growth in breast tissue, though there are other compounds in broccoli that may have contributed to these findings.

Autism

In 2014 a placebo-controlled, double-blind, randomized study was published that examined sulforaphane treatment in 44 young men with autism spectrum disorder.

After 18 weeks, participants receiving placebo experienced minimal change, compared to those receiving sulforaphane who showed substantial improvements in behavior. After stopping sulforaphane supplementation, total scores returned to levels closer to those prior to supplementation.

Another study, published in 2018, looked at autism treated with sulforaphane from broccoli. Fifteen children with autism spectrum disorder and related neurodevelopmental disorders participated in the 12-week study.

The researchers looked at behavior and social responsiveness in relation to sulforaphane supplementation. After the 12 weeks, both behavior and social responsiveness improved, however only the change in the social responsiveness was significant.

The researchers also identified 77 urinary metabolites that were associated with changes in symptoms. These metabolites were found in different physiological pathways, including those relating to oxidative stress, neurotransmitters, hormones, sphingomyelin metabolism, and the gut microbiome.

Cardiovascular Disease

In 2015 a paper was published that reviewed evidence from clinical studies and animal experiments relating to the possible ways in which sulforaphane is protective against cardiovascular disease. 

Because oxidative stress and inflammation are both markers in cardiovascular disease, the researchers concluded that sulforaphanes antioxidant and antiinflammatory properties may play an important role in protecting against heart disease.

Diabetes

A 2012 randomized double-blind study examined the effects of broccoli sprouts on insulin resistance in people with type 2 diabetes. Researchers analyzed glucose and insulin levels in 63 people who received either placebo or broccoli sprouts powder for 4 weeks. 

Results showed a significant decrease in serum insulin concentration and resistance in those receiving broccoli sprouts, supporting the theory that broccoli sprouts may improve insulin resistance in people with type 2 diabetes.

Other

Sulforaphane has been studied for its use in other health conditions, though there is little, if any, quality human studies on these topics. These include: 

• Constipation
• Sun damage of skin
• Osteoporosis
• Neurological diseases
• Obesity

Possible Side Effects

Sulforaphane is safe when consumed in plant form, such as from broccoli or kale. In supplement form, sulforaphane has little, if any side effects. The main side effects seen include digestive problems, such as gas.

Though sulforaphane seems to be well tolerated with minimal side effects, there is not enough quality research to know if it is safe to take by mouth as a medicine, especially in high doses and for long periods of time.

Sulforaphane is safe during pregnancy and breastfeeding when eaten in whole food form, such as from broccoli. It is not known if it's safe when taken as a supplement during pregnancy and breastfeeding, and is therefore not recommended.

Dosage and Preparation

Sulforaphane supplements are most commonly available in the form of tablets, capsules or powder, but can also be bought as a liquid. They are often made from broccoli, broccoli seeds or broccoli sprouts extract.

Some sulforaphane supplements are also advertised as combined with myrosinase enzymes for enhanced absorption. There are no daily intake recommendations for sulforaphane and supplement brands vary widely in how much they suggest taking.

Although there is wide availability of sulforaphane in supplemental form, more research is needed to determine the ideal dose, safety, and effectiveness.

What to Look For

Sulforaphane supplements are not regulated by the Food and Drug Administration (FDA) or any other governmental agency. Because of this, available supplement products can vary greatly in quality, dosage and effectiveness.

Simply reading the label may not provide enough information to make a well-informed buying decision on supplements such as sulforaphane. It’s best to ask your healthcare provider and pharmacist for help in choosing the right supplement for you.

They can guide you toward the best dosage for your needs and recommend a trustworthy product certified by a third party to ensure quality, such as the U.S. Pharmacopeia, NSF International, or Consumer Lab. 

Other Questions

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 a study, raw broccoli has ten times more sulforaphane than cooked broccoli.

If you prefer your cruciferous vegetables to be cooked, steaming might have the least effect on sulforaphane levels. One 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.

Because of this, if you want to take full advantage of the sulforaphane content in your cruciferous vegetables, it’s best to avoid boiling or microwaving them. Instead, choose to eat them raw or lightly steamed.

Which foods are highest in sulforaphane?

As mentioned before, cruciferous vegetables are well known for their sulforaphane content, especially broccoli and broccoli sprouts. Other sulforaphane-containing cruciferous vegetables include:

• Kale
• Cauliflower
• Brussels sprouts
• Cabbage
• Bok choy
• Watercress
• Collard greens
• Mustard greens