What is Sulforaphane?

3,485 words, 18 minutes read time

Updated on November 27, 2023. Fact checked by Robert Underwood, Head of Research

As early as 100 BC, ancient Romans praised the ‘virtuous cabbage plant’ for its medicinal qualities—benefits scientists now know come from the plant chemical sulforaphane. An activator of longevity genes, sulforaphane provides many significant health benefits ranging from disease prevention to supporting brain health and detoxification.

What is Sulforaphane?

Sulforaphane is an isothiocyanate, a special type of organic molecule that contains sulphur atoms. It is formed only after plant matter is destroyed—through chewing, for example—and mixed with a specific enzyme (see below: How is Sulforaphane Formed?).

Isothiocyanates, like sulforaphane, are most commonly found in cruciferous vegetables. These include cabbage, cauliflower, broccoli, brussels sprouts and other members of the Brassicaceae family.

Currently, interest in the health benefits of isothiocyanates like sulforaphane is growing, and a search for “sulforaphane” on Pubmed.gov returns more than 1,800 experimental and clinical trial citations, with over 70% of them published in the last 10 years alone. Most of these studies have focused on sulforaphane in a concentrated form; it is currently uncertain whether the levels available in fresh produce would be as effective.

How Sulforaphane is Formed

As previously mentioned, Sulforaphane is an isothiocyanate, and it is often called a sulphur-rich “plant compound”. While it’s true that sulforaphane comes from cruciferous vegetables like broccoli, it is misleading to think of the compound as something that already exists in the plant. Sulforaphane is produced only after the plant material is damaged. Deconstruction by chewing or processing releases the fundamental chemical precursors to sulforaphane: Myrosinase and glucoraphanin. Myrosinase is an enzyme, and glucoraphanin is a natural plant compound.

Sulforaphane forms only after myrosinase combines with glucoraphanin. If either of these crucial precursors is missing or inhibited, the supplement or food source will ultimately fail to deliver actual sulforaphane and its associated health benefits (for more information, see the Sulforaphane Supplements and Dosage and Prostaphane® sections below).

Overview of Potential Health Benefits and Risks

Disclaimer: Always consult your health care professional prior to making changes in your diet or exercise regimen, including whether to use supplements like sulforaphane. Pregnant women, women who are nursing, and children especially must always consult a physician prior to taking supplements or medications.

The potential sulforaphane health benefits:

• Promote longevity
• Support natural detoxification 
• Reduce inflammation
• Promote cardiovascular health
• Improve brain health
• Help lower cancer risk
• Promote healthy weight management

The potential risks and side effects:

• Heartburn
• Upset stomach

How Does Sulforaphane Work?

Activates Nrf2, the “Master Regulator” of Cell Activity

Modern longevity research has identified several key cellular communication networks that govern how the human body handles stress, inflammation, infection and chronic disease. When it comes to a healthy lifespan, few networks are more important than Nuclear factor erythroid 2-related factor 2, or Nrf2. 

Nrf2 manages the expression of many of the body’s most important genes. For example, Nrf2 is known to activate the antioxidant networks that protect cells from damage and prevent chronic disease, heart disease, stroke and other age-related diseases. Interestingly, lifestyle practices like exercise and fasting also activate this powerful pathway, which may explain why they contribute so profoundly to better health and lower risks of disease later in life.Nrf2 has been called a “master regulator” of cellular activity, capable of controlling the switching on and off of more than 200 genes.

Specifically, it has been shown to:

• Reduce oxidative stress and related disease risks by promoting glutathione production, the human body’s most powerful internal antioxidant.
• Activate detoxification enzymes, thereby protecting the body from both internal and external toxins.
• Promote cellular autophagy, a form of cellular cleanup and the removal of dead cells that lowers the risk of chronic inflammation and disease.
• Regulate the body’s inflammatory response, reducing the risk of disease associated with chronic inflammation.

Sulforaphane’s most powerful mechanism of action lies in its ability to activate Nrf2, creating a cascade of beneficial outcomes downstream. By activating this critical pathway and the 200+ genes it controls, sulforaphane appears to empower the body’s natural systems for healing, disease prevention and cellular longevity.

Deactivates Phase I Detoxification Enzymes

Writing in the Journal of Nutrition, found that sulphur compounds like sulforaphane help to protect against disease. They work by affecting enzymes in the body which break down substances that can turn into disease-causing agents. By stopping these enzymes, sulforaphane may prevent these harmful agents from damaging DNA and causing chronic disease.

Activates Phase II Detoxification Enzymes

In addition to deactivating the enzymes that turn disease-causing molecules into disease, sulforaphane appears to activate a separate set of enzymes that enables the body to detox from them. This was documented in an article published by the Journal of Agricultural and Food Chemistry in 2004. In it, researchers explain that cruciferous vegetables, rich in compounds like sulforaphane, appear to activate Phase II detoxification enzymes, which help to convert disease-causing molecules into water-soluble compounds. In doing so, the body can more easily pass the harmful agents naturally through the urinary system(urine) or digestive tract (via faeces).

Increases Antioxidant Capacity

Antioxidant capacity refers to the body’s ability to reduce reactive oxygen species (ROS) with antioxidants before they have the chance to cause harm. ROS are created as a normal byproduct of day-to-day cellular activity, like metabolism. Often called free radicals, ROS may damage neighbouring cells and cause a state of oxidative stress that researchers believe to be the “pathogenesis (disease development) of a variety of diseases, such as cancer, asthma, pulmonary hypertension and retinopathy”.

To prevent oxidative stress from accelerating the ageing process and increasing the risk of disease, the body must utilise an equally continuous supply of antioxidants as a means to stabilise ROS and prevent damage. Fortunately, the body has a built-in system for producing a potent antioxidant called glutathione—a system that seems to be increased by the intake of sulforaphane-rich foods and supplements. In fact, studies indicate that a diet rich in cruciferous vegetables, like Brussels sprouts, may increase the body’s production of glutathione by an astonishing 140%. As the body’s most powerful internal antioxidant, glutathione significantly improves the body’s antioxidant capacity and ability to defend against damage and age-related disease. 

What Foods Naturally Contain Sulforaphane?

As described above, plants do not naturally contain sulforaphane.  Instead, cruciferous vegetables must be assessed based on their potential to yield this unique compound. Therefore, typically, yield is measured by the extent to which each food item contains the plant chemical precursors that form sulforaphane: glucoraphanin and myrosinase. 

Although sulforaphane yield may vary, studies indicate the best sources for these precursors include:

• Broccoli
• Broccoli sprouts
• Cauliflower sprouts
• Brussels sprouts 
• Cabbage
• Bok Choy
• Arugula (Rocket)
• Cauliflower
• Collard greens
• Kale
• Mustard greens
• Radishes
• Rapini (also called broccoli rabe)

Freshly germinated seeds, commonly referred to as sprouts, seem to be particularly potent sources of the precursors needed to produce sulforaphane. According to the Proceedings of the National Academy of Sciences, broccoli and cauliflower sprouts may contain 10-100 times more glucoraphanin than when they are fully grown plants, which may significantly improve sulforaphane yield. This is one reason why many clinical studies use sulforaphane extracts sourced from broccoli sprouts specifically. 

In addition to the variability in sulforaphane precursors, potential yield is also greatly affected by the plant’s age and preparation method. For example:

• Blanching kale (immersing it in hot water) may increase sulforaphane yield by up to 489%. 
• Microwaving broccoli—a practice that many new-age health practitioners might advise against—may increase sulforaphane yield by about 80%. 
• Broccoli sprouts may yield 10-100 times more sulforaphane than fully-grown broccoli plants.

Such wide variability across so many uncontrollable domains makes it difficult to know if a diet high in cruciferous vegetables will indeed deliver consistent, reliable and therapeutic doses of sulforaphane each day. Not surprisingly, this has caused a significant increase in consumer demand for pure and standardised sulforaphane supplements.

The Problem with Most Sulforaphane Supplements

When seeking therapeutic or medicinal benefits from sulforaphane supplements, the issue is extremely complex due to the many variables that can affect its formation, its subsequent potency and level of effectiveness. 

To better understand how to identify an effective supplement, it helps to first review how sulforaphane is formed:

• Foods that are most associated with sulforaphane and related health benefits, like broccoli, cabbage and Brussels sprouts, do not actually contain sulforaphane in their raw, fresh-from-nature form.
• An enzyme called myrosinase is needed to form sulforaphane, and it is not released until after the vegetables are cut, chewed or otherwise pulverised. 
• Once myrosinase is released, it combines with glucoraphanin, another part of the plant, to create sulforaphane
• Myrosinase is sensitive to various factors like pH and temperature. If the enzyme degrades during storage or digestion, the conversion of glucoraphanin to sulforaphane can be impaired.
• Human gut bacteria may also contain myrosinase, although its ability to convert glucoraphanin to sulforaphane may also vary widely from person to person (the healthier the gut microbiome, the better).

When supplements contain only the precursors (glucoraphanin and myrosinase), the conversion to sulforaphane relies on the body's conditions and processes. This conversion may not be as efficient or consistent as the direct intake of free-form sulforaphane. Factors like gut flora, pH, and individual variations in myrosinase activity can influence the conversion rate and efficiency. If the product contains only the precursors, then consumers cannot expect a consistent yield from the product. 

As in nature, there are many variables that may affect how a precursors-only supplement formula falls short of providing therapeutic doses of sulforaphane. These include wide variations in plant material, harvesting practices, encapsulation techniques and supplement storage, just to name a few. 

Moreover, many supplements are labelled as “sulforaphane” but contain only glucoraphanin and no myrosinase. Without the latter, the conversion of glucoraphanin to sulforaphane relies entirely on the prevalence of myrosinase in the consumer’s gut flora or microbiome. This poses a challenge when assessing broad effectiveness because:

• Everyone is different - the microbiome is so vast and unique that researchers believe it is like a fingerprint that can differentiate one person from another.
• Poor diet, antibiotics, stress and other aspects of one’s environment may cause significant imbalances in gut bacteria.

Prostaphane®: A Clinically Proven Solution

To date, only one supplement offers free-form stabilised sulforaphane, and that’s Prostaphane®. Developed by Triballat Ingrédients. This patented formulation guarantees both stability and bioavailability to ensure consumers always receive a therapeutic dose of sulforaphane. 

A 2017 study published by Molecular Nutrition and Food Research found Prostaphane to be significantly more bioavailable than the three most common alternative forms of sulforaphane. Specifically, findings indicate that:

• Glucosinolates alone yield about 4% bioavailable sulforaphane
• Glucoraphanin yields about 10% bioavailable sulforaphane
• Glucoraphanin paired with myrosinase yields about 20-40% bioavailable sulforaphane, depending on the individual (likely due to differences in gut health)
• Prostaphane yields about 70% bioavailable sulforaphane

Prostaphane is clinically proven to be effective. In a French clinical trial, Prostaphane was shown to reduce the expression and metastasis of prostate cancer cells in a dose-dependent manner.

Although more clinical trials are needed, these results indicate that Prostaphane may exhibit all four mechanisms of action detailed in the How Does Sulforaphane Work? section above. Specifically, it is likely that the free-form, stabilised formula inhibits the metabolism of pro-carcinogenic agents, while simultaneously activating the phase II enzymes that enable the body to excrete them safely. 

Potential Health Benefits of Sulforaphane

Promotes Longevity

Cruciferous vegetables have long been associated with good health and vitality. For example, a 2011 cohort study of more than 135,000 Chinese men and women found that those who consumed a diet rich in cruciferous vegetables had a 22% reduced incidence of all-cause mortality. Although the study did not assess sulforaphane consumption directly, researchers partly attributed the findings to the fact that cruciferous vegetables are rich in organic sulphur-containing compounds—the phytochemicals now known to act as sulforaphane precursors. According to the study authors, these compounds demonstrate the ability to detoxify, protect the body from disease-causing molecules, and are likely a key longevity mechanism. 

Cruciferous vegetables may also promote a healthy epigenome. Whereas the genome consists of genes that act as fundamental blueprints for cell creation, the epigenome acts as a control mechanism that determines which genes are actively switched on, and which are not. Diet may affect the epigenome, and a cruciferous-rich diet is associated with a longer health span and a reduced risk of age-related disease.

As documented above, one of sulforaphane’s key mechanisms of action lies in its ability to activate Nrf2 and the 200+ genes it regulates. This is another key to the longevity benefits associated with cruciferous vegetables and sulforaphane (see above, How Does Sulforaphane Work?)

Enhances Natural Detoxification

There are three known phases of detoxification:

• De-activation of the toxin by the liver
• Activation of enzymes that break down the toxin so it can return to the bloodstream
• Excretion by way of urine or biliary system

Each phase must work in tandem in order to effectively excrete toxins from the body. 

As cited above, sulforaphane favourably modulates the phase I and phase II enzymes responsible for breaking down and excreting toxins (see How Does Sulforaphane Work? above). Interestingly, it appears sulforaphane further promotes detoxification by promoting liver health. 

In 2021, an article published by The Journal of Nutritional Biochemistry found sulforaphane to promote healing in the liver of mice with alcoholic liver disease. Specifically, the plant compound appeared to attenuate organ damage, reduce fat accumulation and promote oxidative balance within the liver tissue. Commenting on the study, researchers called sulforaphane a “novel therapeutic strategy” that would maybe someday help human patients to recover from such disease.

Although researchers admit the precise mechanisms of action are not well understood, it seems sulforaphane treatment had several positive outcomes, including:

• Reduced fat accumulation in the liver
• Reduced reactive oxygen species (ROS) levels
• Reduced weight gain from subjects’ high-fat diets
• Alleviated symptoms of insulin resistance
• Reduced cholesterol

Reduces Inflammation

Chronic inflammation is one of the biggest contributors to cardiovascular disease and other age-related diseases. As previously mentioned, a diet rich in cruciferous vegetables may reduce inflammation and the risk of such disease, likely from sulforaphane’s impact on the body’s Nrf2 pathway and inflammation-regulating systems. 

In a study published by the Journal of Nutrition, participants eating a cruciferous-rich diet experienced a reduction in systemic inflammation after just 14 days. Commenting on the study, researchers indicated that the diet had the most profound effect on interleukin-6 (IL-6), a cytokine protein that helps the body mediate inflammation. 

Researchers found similar results in a randomised, double-blind, placebo-controlled study published by the Journal of Functional Foods in 2012. In it, diabetic patients were given 10 grams of broccoli sprouts extract for four weeks. At the end of the testing period, those patients saw a decrease in systemic inflammation as marked by IL-6 and C-reactive protein measures. Notably, the authors concluded that “high-sulforaphane BSP [broccoli sprouts powder] could have favourable effects on inflammatory markers in type 2 diabetic patients.”

Promotes Cardiovascular Health

Protection against cardiovascular disease seems to be another benefit of sulforaphane’s ability to activate the Nrf2 pathway. In a 2011 study published by the peer-reviewed journal Oxidative Medicine and Cellular Longevity, researchers indicated that sulforaphane may help to prevent cardiovascular disease because it has “beneficial effects[…] due to its antioxidant and anti-inflammatory properties”.

Improves Brain Health

Thus far, each of the above health benefits may significantly promote anti-ageing effects and increase the human health span. Promoting longevity, preventing chronic disease, reducing inflammation, improving cardiovascular health and effective detoxification are all essential components of long-term health and well-being. Sulforaphane may further support anti-ageing by bolstering glutathione in the brain— increasing the bioavailability of the body’s most potent antioxidant in what is arguably its most important organ.

In a clinical pilot study published by the journal Molecular Neuropsychiatry in 2018, researchers found a “consistent increase in [subjects’ brain] glutathione levels” after just 7 days of supplementing with sulforaphane. Although more research is needed, this is a significant finding for at least three major reasons:

• Oxidative stress is increasingly being linked to brain disorders
• Brain glutathione levels are known to decrease as humans age
• A powerful antioxidant, like glutathione, may help to reduce oxidative stress and prevent brain degradation.

May Promote Weight Management

Sulforaphane may also help individuals to maintain a leaner, more healthy body. Research is ongoing, but two significant findings include sulforaphane’s ability to increase brown fat, inhibit adipogenesis (creation of ordinary fat cells), and activate the AMPK pathway. 

In a cell study published by Molecular Nutrition and Food Research, sulforaphane was found to convert ordinary fat cells to brown fat cells. Brown fat contains more mitochondria than ordinary fat cells, which increases an individual’s total daily calorie requirement. All else being equal, this phenomenon may help prevent calorie surpluses—which are often the result of eating too much and/or exercising too little—from causing weight gain.

In an animal study, researchers found sulforaphane to promote healthy weight management in two other key ways: By reducing adipogenesis and activating AMPK pathway. 

Adipogenesis is the process where fat cells absorb more fat, leading to their growth and weight gain. Sulforaphane seems to slow down this process, which helps in reducing the conversion of dietary calories into body fat. Additionally, it activates the AMPK pathway. This pathway is crucial in regulating energy within cells. When it is activated, it helps the body use energy more efficiently and boosts metabolism – the process by which the body converts food into energy. This improved energy metabolism can contribute to maintaining a healthy weight, as it helps the body balance its energy needs more effectively. Essentially, activating the AMPK pathway can lead to better energy management in the body, which is a key factor in weight control.

Sulforaphane Supplements and Dosage

The daily sulforaphane dose found to achieve beneficial outcomes in most of the available clinical trials is around 10-40 mg.

For context, this would be equal to 1-4 capsules of Prostaphane. To achieve this optimum level with other sulforaphane precursor supplements would mean taking considerably more capsules.

Only Prostaphane studies related to prostate-specific antigen levels (PSA) advise that an amount up to 60mg may be appropriate. However, we would not recommend this quantity without medical approval for specific conditions.

Important Note: Many supplements are labelled as “sulforaphane” but contain only chemical precursors, like glucoraphanin. Always check the ingredients and nutrition labels carefully. If the product has only glucoraphanin, it is unlikely to yield sulforaphane after consumption.

Potential Side Effects and Drug Interactions

Sulforaphane supplements are generally considered safe and well tolerated, with occasional side effects limited to heartburn and upset stomach. In clinical studies, sulforaphane supplementation has been safely administered for up to 6 months at a time. Although this is the longest amount of time continuous supplementation has been studied, it may be safe to take it beyond this for general lower-dose health purposes. However, we would still recommend a break if you wish to continue beyond 6 months and suggest monitoring for side effects.

As a key effect of sulforaphane supplementation is detoxification, it is recommended to be cautious in order to manage detoxification side effects known as “Herxheimers”.

“Herxheimers” are sudden detox reactions characterised by fatigue, rashes, nausea and malaise, and can be caused by ingesting high doses of Nrf 2 activators. Whilst these reactions are not commonplace, they have been reported by individuals who supplement with higher quantities of these compounds.

Sulforaphane is not only a potent Nrf2 inducer but also highly bioavailable, and even modest doses can produce significant clinical responses.

Sulforaphane may interact with certain medications as it’s known to alter the enzymes involved in drug metabolism or how they are broken down, used and removed from the body. Research has specifically investigated the interactions of sulforaphane with three common drugs: furosemide, verapamil and ketoprofen.

These interactions can change the activity of enzymes in the drug metabolism and the way the drugs are then moved around the body. This may potentially lead to changes in the effectiveness of the aforementioned compounds.

Sulforaphane may also interact with medications that are metabolised by the liver. This is particularly important because sulforaphane can increase the activity of the liver enzyme cytochrome P450. This might speed up the metabolism of some medications, resulting in decreased efficiency.

Since sulforaphane has blood sugar-lowering effects, it may also interact with medications that influence blood glucose levels​​.

Lastly, Sulforaphane has been shown to influence thyroid function in people with low levels of iodine, special precaution is therefore warranted by individuals who suffer from thyroid disorders.

Conclusion: Sulforaphane is a Well-Tolerated Longevity Essential

Few plant compounds offer more longevity benefits than sulforaphane. While a diet rich in cruciferous vegetables has long been the only way to receive the benefits of sulforaphane, new advances make it possible to take a safe, reliable and stabilised sulforaphane supplement for the benefit of maximum therapeutic impact. 

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