As a provider of functional and integrative medicine I am constantly searching for low-risk, high-upside interventions that can promote health in my patients. Over-the-counter and pharmaceutical medications, while very important in many situations, typically alleviate individual symptoms by blocking or promoting specific biochemical reactions in the body and thus do not promote systemic health and well-being otherwise. Various dietary patterns, exercise, stress reduction, and quality sleep are good examples of foundational interventions that can promote health in a number of different ways—they don’t just work on one specific pathway, but rather have many positive effects across the entire body. Many natural compounds or “phytochemicals” can work in a similar way, benefitting the body through a wide variety of mechanisms (albeit usually less powerfully than those fundamental diet and lifestyle interventions!). One exciting natural compound that you may not have heard of, and which has research scientists excited, is called sulforaphane.
What is sulforaphane?
Sulforaphane is what is called an isothiocyanate, and is found in cruciferous vegetables such as brussel sprouts and broccoli. Isothiocyanates are a type of chemical defense system for these plants, and are at least in part responsible for their bitter taste. The most potent dietary source of sulforaphane, by far, is broccoli sprouts. Interestingly, sulforaphane is not actually readily available in the cruciferous vegetables until they are chewed or boiled. These actions lead to an enzymatic reaction in which a compound called glucoraphanin is converted into sulforaphane by the enzyme myrosinase.
Why are we interested in sulforaphane?
Sulforaphane was ultimately identified as a potential topic of interest after many observational studies had suggested potent benefits from consuming cruciferous vegetables. In 2011, a study was published in The American Journal of Clinical Nutrition in which researchers analyzed the dietary patterns of more than 134,000 Chinese adults. They found that cruciferous vegetable intake was associated with a significant reduction in risk of death at multiple follow-up time points. In 2019, another study conducted in Japan analyzed data from 88,184 study participants and again found that those who consumed more cruciferous vegetables experienced significant reductions in risk of death, around 14% in men and 11% in women.
Following these observations, research has been done to try and uncover reasons for the benefits of cruciferous vegetables. Subsequent studies have identified sulforaphane as one likely reason for the observed benefits. One of the primary reasons sulforaphane is thought to be so beneficial is its induction of the Nrf2 genetic pathway. This pathway regulates over 200 genes including antioxidant and anti-inflammatory genes, as well as those that detoxify and inactivate harmful compounds. Side note—this is an important reminder that although our genes are “set”, the expression or activity of our genes is not, and a number of factors influence how those genes actually behave.
Benefits of Sulforaphane
So what are the potential benefits of sulforaphane? Cancer prevention is one. A number of studies have shown sulforaphane supplementation to inhibit tumor growth and/or spread in cell cultures and animal models. More studies are needed in humans, but some have had promising results. For example, in this 2015 trial, men who supplemented with sulforaphane had a decrease in recurrence of prostate cancer following surgery. We don’t yet fully understand just how potent the effects are, but it clearly has anti-cancer properties.
A potential driver of this protective effect against cancer could be driven by sulforaphane’s capacity to increase detoxification. All isothiocyanates are known to activate phase II detoxification enzymes, which can help deactivate pro-carcinogens and allow them to be removed from the body. An impressive randomized clinical trial from 2014 found that those living in an area with high levels of air pollution experienced a substantial increase in the urinary excretion of toxins following consumption of a broccoli-sprout (the highest source of sulforaphane!) beverage. Benzene excretion was increased by 61% relative to those who did not consume the beverage.
Another likely benefit of sulforaphane is neuroprotection. The Nrf2 pathway is the body’s strongest protective force against oxidative stress, which is one of the key mechanisms that drives neurocognitive decline. One study supporting this antioxidant role was an animal model of spinal cord injury in which sulforaphane was found to be neuroprotective and lead to better recovery. A 2013 study found that in a mouse model of Parkinson’s disease sulforaphane significantly slowed the progression of Parkinson’s. Researchers believed this was in part due to sulforaphane’s ability to increase glutathione levels, the body’s master antioxidant. Interestingly, one human clinical trial from 2020 found that sulforaphane reduced irritability in those with autism spectrum disorder. It may also have some potential for mental health conditions, perhaps due to sulforaphane’s ability to reduce inflammation. One trial in humans found that sulforaphane reduced depressive symptoms.
There are a host of other benefits with support in the scientific literature which I won’t dive into deeply now, but include: improved metabolic health, anti-inflammatory effects, and enhanced immunity. It should be noted that not every study out there has had positive effects. There are some studies which have shown no effect or only small effects from sulforaphane, and we still don’t fully understand how impactful sulforaphane will be for any given condition or how to optimally dose it. This will come with time. But enough positive research has been done to suggest it is a safe compound to use with a lot of potential upsides!
How do I consume meaningful amounts of sulforaphane?
First and foremost, I recommend you increase your consumption of cruciferous vegetables, including broccoli, kale, brussel sprouts, cabbage and cauliflower. You will receive a number of benefits from eating more of these foods beyond just sulforaphane.
Side note: you may have heard that those with thyroid disease should not consume cruciferous vegetables. The basis for this is that they are high in “goitrogens” which can compete for iodine uptake, a mineral critical for thyroid health. I acknowledge that this can be an issue in select cases, however, unless there is a deficiency of iodine to begin with (relatively rare), this is typically not an issue and the upsides of cruciferous vegetables outweigh the potential downsides!
In order to achieve the levels of sulforaphane used in many of the studies suggesting benefit from your diet, broccoli sprouts are by far the best way to get the necessary dose. Consuming 50-100g of broccoli sprouts daily would get you in the range of some of the doses used in scientific research. Some people may prefer this method, but if you would like to supplement that is also an option. You want to be careful about selecting your supplement, as not all products are created equal. Some products contain only the sulforaphane precursor and you will be unlikely to convert enough to sulforaphane. You want to look for products with either stabilized sulforaphane, or at least myrosinase enzyme to support the conversion to sulforaphane. I’ll include a link to a product below that I believe to be of high quality.