Evidence: High Possible Benefits: Very High Safety: Very High
TABLE OF CONTENTS
What is sulforaphane?
Sulforaphane is the main bioactive compound in cruciferous vegetables, such as broccoli, cauliflower, and Brussels sprouts. More precisely, these vegetables contain glucoraphanin, which converts into sulforaphane in the body. By far the richest dietary source of sulforaphane is broccoli sprouts, which contain approximately 0.45 mg of sulforaphane per gram. Sulforaphane is a promising chemical that is currently being studied for its anti-aging and anti-cancer effects. Sulforaphane can reduce inflammation, boost antioxidant defenses, improve cholesterol levels, and more. This article is about the main benefits of sulforaphane, its potential side effects, the best time to take it, and more.
Possible benefits
All of the potential benefits mentioned below are dose-dependent. As with other vegetable supplements, there is a sweet-spot dose that allows you to get most of the benefits without causing meaningful side effects or tolerance buildup in the body. We will discuss the best dosing protocol later in this article.
Major benefits
Anti-cancer effects – Sulforaphane and a few other compounds in cruciferous vegetables appear to have strong anti-cancer effects. Sulforaphane supplementation was shown to slow down cancer growth and possibly help reverse it. It can significantly lower cancer mortality for prostate, bladder, lung, and breast cancer. This benefit likely applies to other types of cancer as well but more research is needed to confirm this.
Antioxidant properties – This compound contains various antioxidants, such as sulforaphane, and can help reduce oxidative stress in the body.
Reduced inflammation – Sulforaphane can greatly reduce chronic inflammation in most people.
Minor benefits
Detoxification – Sulforaphane supplementation was shown to increase benzene excretion by 61% in humans. This benefit is most notable for people exposed to high levels of benzene, such as smokers.
Improved immune health – This benefit is secondary to the compound’s antioxidant and anti-inflammatory properties. Some people, especially those with autoimmune conditions, may experience a temporary worsening of their immune health after they take this compound. That is generally nothing to worry about as it’s often just a sign of a hormetic response that helps adapt your body to the supplement and other stressors.
Reduced unpleasant symptoms of autism – Sulforaphane was shown in human studies to improve behavior in people with autism.
Improved cognition in Schizophrenics – Sulforaphane can reduce cognitive impairment in people with Schizophrenia to some extent.
Lowered blood glucose – While more studies are needed to confirm this benefit, sulforaphane may improve blood sugar levels in some people, especially those with insulin resistance or diabetes.
Improved cholesterol levels – Cruciferous vegetables were shown in multiple studies to improve cholesterol levels by reducing LDL and increasing HDL cholesterol levels in the body. Sulforaphane was also shown to significantly lower LDL oxidization.
Lowered triglycerides – Supplementation may be somewhat beneficial, especially for people with high triglycerides.
Increased healthspan and lifespan – While the relationship between sulforaphane and healthspan or longevity hasn’t been studied directly, this supplement has many mechanisms through which it might slow down aging and protect your body from various diseases.
Possible side effects
The side effects below are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.
Iodine deficiency – Sulforaphane and other compounds in cruciferous vegetables can deplete the body of iodine, which may cause a variety of thyroid health problems in people who are already deficient in iodine. However, this effect is not too common and shouldn’t be a concern unless you know you are deficient.
Initial adverse reaction – When you start taking sulforaphane, things can get worse before they get better. This supplement can temporarily worsen some aspects of your health and even make you sick after taking it. That can be unpleasant, but it is usually a sign that the supplement is working and creating a hormetic response that allows the body to adapt and become more resilient in the long term. People with an autoimmune condition should be careful as the initial adverse reaction may be intense. If you have an autoimmune disease, start with a small dose or amount and gradually build your way up.
Allergic reaction – Some people are allergic to this compound or to cruciferous vegetables and may experience an allergic reaction after they start taking it. Unlike the “initial adverse reaction,” allergic reactions typically don’t disappear until one stops taking the supplement.
Diarrhea – You can usually prevent diarrhea or stomach discomfort by taking this supplement with a meal. Taking sulforaphane with food is better regardless because it absorbs better that way.
Toxicity – Sulforaphane has adaptogenic properties and acts as a mild stressor on the body. That is usually a great thing as it allows your body to adapt to specific forms of stress and become more resilient. However, stressing the body too much can be counter-productive and cause multiple side effects, including toxicity. While acute toxicity is extremely rare, taking high amounts of this compound could lead to chronic toxicity and cause health problems over time. To prevent chronic toxicity or the buildup of tolerance, staying below 140 grams of fresh broccoli sprouts or 60 mg of sulforaphane in a day is best unless you have a great reason to take more.
Contamination – If growing or storing conditions are not adequately controlled, broccoli sprouts or other sources of sulforaphane can be contaminated with bacteria, molds, and other potentially harmful microorganisms. Many growers also use pesticides that can be unsafe. Choose the brand you get vegetable supplements from wisely. It is often best to use websites like Amazon, where thousands of users have reviewed and rated the products. You are less likely to buy something of lower quality there.
experience a severe adverse reaction after taking the supplement
have an autoimmune condition that makes your immune system overreact to xenohormetic stressors (you can take this compound in that case, but it’s best to start with low amounts)
Who will benefit the most?
You should consider taking the supplement or adding cruciferous vegetables to your diet if you:
have cancer or are predisposed to cancer
have autism
wish to improve general health
are a smoker
have a high budget for supplements and are willing to experiment with a variety of them (assuming you don’t fall into any of the categories that should avoid this supplement, sulforaphane appears safe and is unlikely to do more harm than good for most people)
How much sulforaphane should you take?
Because sulforaphane is an adaptogenic compound, it acts as a mild hormetic stressor on the body, which allows your body to adapt and become more resilient to certain kinds of stressors in the long term. A higher dose of these adaptogens isn’t necessarily better because they may stress out the system too much.
The sweet-spot dose of sulforaphane is about 40-60 mg, which can be obtained from 100-140 grams of fresh broccoli sprouts. The higher end of this range usually provides slightly more benefits in the short term. If you plan to take the supplement regularly for a longer time (multiple months or years), the lower end is probably a better way to go.
You would develop tolerance to sulforaphane faster if you took higher amounts. Additionally, very high doses can put too much pressure on your system and cause health problems if you take the supplement for a prolonged period.
While this supplement could theoretically cause acute toxicity, you’d need to take an extremely high amount that would be way beyond what even the most potent supplements contain.
Like most other plants, it is best to cycle sulforaphane and take about two days off weekly to reset your tolerance to it. That will allow you to keep getting the benefits in the long term.
Best time to take sulforaphane
It is better to take sulforaphane and eat cruciferous vegetables with food or a dietary source of fat.
Whether you take this supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
Interactions
Iodine Sulforaphane may deplete the body of iodine and cause health problems if you are already deficient in this mineral. You can prevent this side effect by taking iodine supplements or drinking water rich in this mineral.
Mustard seeds Mustard seeds contain myrosinase, an enzyme that can greatly improve the bioavailability of sulforaphane (or the conversion of glucoraphanin into sulforaphane).
As with most other vegetable supplements, it is best to cycle sulforaphane and take a break from it for about two days per week to reset your tolerance back to baseline. That will keep your body sensitive to compound and allow you to keep getting the benefits in the long term.
This supplement by itself should not worsen your sleep quality in any way. However, it’s best to take it with food, and you generally don’t want to eat any food right before bed as it could worsen your digestion and sleep quality.
Dry broccoli sprout powders and sulforaphane supplements can expire but not nearly as fast as fresh vegetables. They can also lose potency over time but very slowly if you store them well. Keep the supplement in a cold, dark, and dry place. It should remain just as potent for many months or even years there.
Yes. Sulforaphane acts as a mild stressor on the body. That is usually a great thing as it allows your body to adapt to specific forms of stress and become more resilient. However, stressing the body too much can be counter-productive and cause multiple side effects, including toxicity. While acute toxicity is extremely rare, taking very high amounts of this compound could lead to chronic toxicity and cause health problems over time. High doses can also make you develop tolerance much faster than lower doses, and they may be less effective at improving health in the long term.
While you could safely take higher doses, there is usually no point in eating more than 140 grams of fresh broccoli sprouts or 60 mg of sulforaphane daily. This amount should give you most of the benefits without meaningful side effects.
Unfortunately, there is not much information about the half-life of sulforaphane in the body. However, most of the effects of this chemical are cumulative, so they mostly happen in the long term rather than acutely. Therefore, the half-life of this supplement isn’t very relevant in practice.
Sulforaphane itself won’t break a fast. If you get sulforaphane from broccoli sprouts, they are very low in calories and unlikely to impact your fast in any negative way.
References
Most of the information in this guide is based on scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything you read in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.
