By Dr. Mercola
Broccoli, a close relative of Brussels sprouts, cabbage and cauliflower, is perhaps most well-known for its chemoprotective properties. It's an excellent source of phytonutrient glucosinolates, flavonoids and other health-boosting antioxidant and anticancer compounds. One of the compounds in broccoli known to have anticancer activity is sulforaphane, a naturally occurring organic sulfur.
Studies have shown sulforaphane supports normal cell function and division while causing apoptosis (programmed cell death) in colon,1 prostate,2 breast3 and tobacco-induced lung cancer4 cells, and reducing the number of cancerous liver tumors in mice.5 Three servings of broccoli per week may reduce your risk of prostate cancer by more than 60 percent.6
Its beneficial effects on obesity, Type 2 diabetes and nonalcoholic fatty liver disease (NAFLD) have also been highlighted in a number of studies. Researchers have now identified yet another major health benefit of this cruciferous vegetable: a healthy gut. In fact, researchers suggest broccoli can be very helpful in the treatment of colitis and leaky gut.7,8,9,10 As reported by CBS:11
"The Penn State study was carried out with mice, who were found to be much more capable of tolerating digestive issues than those who weren't put on a broccoli diet. The scientists added that the results could be a breakthrough for humans, as digestive problems can reportedly lead to other severe issues."
Broccoli Helps Heal a Leaky Gut
What they discovered is that when you eat broccoli, a compound called indolocarbazole (ICZ) is produced, which catalyzes a healthy balance not only in your gut but also in your immune system, as the two are intricately connected. In this study, 15 percent of the animals' diet was swapped out for raw broccoli, equating to a human eating 3.5 cups of broccoli per day.
Admittedly, that's quite a bit of broccoli, but the researchers note you can obtain an equivalent amount of ICZ from a single cup of Brussels sprouts, as they contain three times the ICZ of broccoli. Earlier studies had confirmed that one of the health benefits of broccoli is its ability to quench inflammation, so it makes sense it would be helpful for gastrointestinal (GI) inflammation as well.
Leaky gut is a condition that occurs due to the development of gaps between the cells (enterocytes) that make up the membrane lining your intestinal wall. These tiny gaps allow substances such as undigested food, bacteria and metabolic wastes that should be confined to your digestive tract to escape into your bloodstream.
Once the integrity of your intestinal lining is compromised, allowing toxic substances to enter your bloodstream, your body experiences a significant increase in inflammation. Your immune system may also become confused and begin to attack your own body as if it were an enemy — a hallmark of autoimmunity disorders.
Chronic inflammation in your body can also contribute and/or lead to other health conditions such as arthritis and heart disease. While leaky gut syndrome is primarily associated with inflammatory bowel diseases like Crohn's and ulcerative colitis and celiac disease, even healthy people can have varying degrees of intestinal permeability leading to a wide variety of health symptoms, and this can be significantly influenced by your diet.
Removing lectins from your diet will also go a long way to healing a leaky gut. You can learn more about the details of this in the previous interview I did with Dr. Steven Gundry, who wrote the book "The Plant Paradox."
How Broccoli Improves Gut Function
A key component of a healthy gut is having good barrier function to prevent particles from escaping from your intestinal tract into your bloodstream. Receptors located on the lining of your gut wall called aryl hydrocarbon receptors (AHRs) play a vital role in maintaining a well-functioning barrier. One of their primary jobs is to trigger a reaction when toxins are detected.
As mentioned, broccoli and other cruciferous vegetables contain glucosinolate compounds, which are broken down into ICZ and other byproducts during digestion in your stomach. By binding to and activating AHR, ICZ helps boost your immune function and improve the balance of the microbiome in your gut.
The compound sulforaphane also inhibits inflammation by reducing damaging reactive oxygen species (ROS) by as much as 73 percent.12 Sulforaphane is also an immune stimulant,13 so broccoli beneficially influences your immune function in more ways than one.
Interestingly, excessive activation of AHR will have an opposite, detrimental effect. According to the researchers in the featured study, dioxin activates this receptor, but in this case the resulting hyperactivation triggers toxicity. Lead author Gary Perdew, professor of agricultural sciences, said,14 "What we were interested in is: Could you locally activate the receptor naturally at a level that would cause only modest AHR activation in the gut, but not cause systemic activation, which could possibly lead to negative effects?"
The answer, as you may have guessed, is yes, you can — with cruciferous vegetables. Importantly, broccoli and other sulfur-rich cruciferous vegetables also improve detoxification, which is another important factor that influences your health, including your gut health. Broccoli sprouts, in particular, have been shown to help detox environmental pollutants such as benzene.15,16,17 As noted by The World's Healthiest Foods:18
"… [S]ulforaphane increases the activity of the liver's phase 2 detoxification enzymes. These enzymes … are well-known for their ability to clear a wide variety of toxic compounds from the body including not only many carcinogens, but also many reactive oxygen species, a particularly nasty type of free radical.
By jump-starting these important detoxification enzymes, compounds in crucifers provide protection against cell mutations … and numerous other harmful effects that would otherwise be caused by these toxins."
The Importance of Fiber for Healthy Gut Function
Broccoli and other members of this family are also good sources of fiber — another important ingredient for good gut health. Fiber helps nourish your gut microbiome to strengthen your immune function and reduce your risk of inflammatory diseases.19 Fiber also activates a gene called T-bet, which is essential for producing immune cells in the lining of your digestive tract.20
These immune cells, called innate lymphoid cells (ILCs), help maintain balance between immunity and inflammation in your body and produce interleukin-22, a hormone that helps protect your body from pathogenic bacteria. ILCs even help resolve cancerous lesions and prevent the development of bowel cancers and other inflammatory diseases.
Broccoli Has Many Valuable Health Benefits
As you can see, the benefits of broccoli are significant, making it well worth adding a few spears and/or broccoli sprouts to your meals on a regular basis. Doing so has been shown to:21
Boost mitochondrial health and energy metabolism via nicotinamide mononucleotide (NMN), an enzyme in broccoli that your body needs to produce nicotinamide adenine dinucleotide (NAD).
NAD may slow age-related decline in health by restoring your metabolism to more youthful levels22,23,24 Once in your system, NMN is quickly converted into NAD
Aid with weight loss. Sulforaphane has been shown to slow weight gain, especially the accumulation of dangerous visceral fat, by speeding up tissue browning, a heat-generating type of fat that burns energy rather than storing it, and decreasing gut bacteria associated with obesity25,26,27
Boost overall immune function, thanks to compounds such as diindolylmethane (DIM). DIM has also been shown to be a valuable player in the prevention and treatment of cancer28,29
Lower your risk for atherosclerosis and neurodegenerative diseases such as Parkinson's and Alzheimer's, thanks to phenolic compounds that reduce free radicals
Improve digestion and gut health, courtesy of significant amounts of fiber and AHR-activating ICZ
Support eye health, thanks to high levels of the carotenoids lutein and zeaxanthin
Benefit your skin, as sulforaphane helps repair skin damage
Fight allergies, thanks to the flavonoid kaempferol
Provide important vitamins and minerals, including magnesium, potassium, calcium, protein and vitamin C
Help reduce blood sugar levels, as it contains both soluble fiber and chromium
Support heart health and help prevent thickening of your arteries
Reduce your risk of developing NAFLD by lowering triglyceride levels in your liver30,31
Reduce inflammation, which is at the root of many chronic diseases, including asthma, Type 2 diabetes and heart disease32,33,34
Improve Type 2 diabetes by lowering blood glucose levels and improving gene expression in your liver35,36
How to Get the Most Out of Your Broccoli
Contrary to what you might think, the medicinal qualities of mature broccoli are actually optimized through cooking. Precision is key, however, as there's a fine line between optimizing its nutrient content and destroying it through overcooking. Here are some tips and guidelines to help you get the most out of your broccoli:
• Adhere to ideal cooking times: Research37 shows steaming mature broccoli spears for three to four minutes will increase the available sulforaphane content by eliminating epithiospecifier protein — a heat-sensitive sulfur-grabbing protein that inactivates sulforaphane — while still retaining the enzyme myrosinase, which converts glucoraphanin to sulforaphane. The latter is important, because without myrosinase, you cannot get absorb the sulforaphane.
Make sure you do not exceed the five-minute mark, as you start losing valuable compounds beyond that point. If you opt for boiling, blanch it in boiling water for no more than 20 to 30 seconds, then immerse it in cold water to stop the cooking process.
• Eat cruciferous veggies with mustard seed powder or other myrosinase-rich food: Eating your cruciferous veggies with a myrosinase-containing food38 such as mustard seed powder, which contains a particularly resilient form of myrosinase,39 will further maximize sulforaphane content. Aside from mustard seed, other alternatives include daikon radishes, wasabi, arugula or coleslaw. Adding a myrosinase-rich food is particularly important if you eat the broccoli raw, or use frozen broccoli.
• Opt for fresh: Ideally, use raw, freshly harvested broccoli whenever possible as frozen broccoli has diminished ability to produce sulforaphane. This is because myrosinase40 is quickly destroyed during the blanching process.41 Broccoli can also lose 80 percent of its glucoraphanin — the precursor of sulforaphane — in the first 10 days after harvest.
• For recipes calling for longer cooking times, chop and wait before cooking: When a cruciferous vegetable is chopped, myrosinase is activated. So, by chopping the food and waiting about 40 minutes, the sulforaphane will have formed, allowing you to cook the food in excess of the recommended three to four minutes of steaming, or 30-second blanching, without risking sulforaphane loss.42
The reason for this is because both the precursor to sulforaphane and the sulforaphane itself are largely resistant to heat. It's the myrosinase that gets destroyed during cooking, which then prevents the formation of sulforaphane. By allowing the sulforaphane to form before you cook it, you circumvent this chain of events. As an example, if making broccoli soup, blend the raw broccoli first; wait 40 minutes for the sulforaphane to form, then boil it.