By Dr. Mercola
• Supports normal cell function and division and acts as an immune stimulant1
• Causes apoptosis (programmed cell death) in colon,2 prostate,3 breast4 and tobacco-induced lung cancer5 cells; three servings of broccoli per week may reduce your risk of prostate cancer by more than 60 percent6
• Activates nuclear factor-like 2 (Nrf2), a transcription factor that regulates cellular oxidation and reduction and aids in detoxification,7 as well as other phase 2 detoxification enzymes.
Broccoli sprouts, in particular, have been shown to help detox environmental pollutants such as benzene.8,9,10 In another study, sulforaphane was found to increase excretion of airborne pollutants by 61 percent.11 The phytonutrients glucoraphanin, gluconasturtiin and glucobrassicin also aid detoxification12
• Reduces damaging reactive oxygen species (ROS) by as much as 73 percent, thereby lowering your risk of inflammation,13 which is a hallmark of cancer. It also lowers C-reactive protein, a marker of inflammation14
• Reduces the expression of long noncoding RNA in prostate cancer cells, thereby influencing the micro RNA and reducing the cancer cells’ ability to form colonies by as much as 400 percent15,16,17,18,19
However, the health benefits of this cruciferous veggie do not end there. Research shows it may reduce your risk for a number of common diseases, including but not limited to arthritis, heart disease and kidney disease. Most recently, its beneficial effects on obesity and type 2 diabetes have been highlighted.
Sulforaphane Helps Slash Obesity Risk
Animal research20,21,22,23 suggests sulforaphane may be used as a weight management aid. Mice fed a high-fat diet with sulforaphane gained weight at a rate that was 15 percent slower than those receiving the same diet without sulforaphane supplementation. They also gained 20 percent less visceral fat, the fat that collects around your internal organs, which is particularly hazardous to health. Two different mechanisms behind these effects were discovered
- First, sulforaphane was found to speed up tissue browning. Brown fat is a beneficial type of body fat that actually helps you stay slim. It’s a heat-generating type of fat that burns energy rather than storing it
- Sulforaphane also decreased gut bacteria in the Desulfobivrionaceae family. These bacteria are known to produce toxins that contribute to metabolic endotoxemia and obesity
Broccoli in the Treatment of Diabetes
Results from a Swedish study24,25 suggest sulforaphane may be helpful in the treatment of diabetes as well, lowering blood glucose levels and improving gene expression in your liver. Medical News Today reports:26
“While there are medications, such as metformin, that can help people with type 2 diabetes to manage their blood glucose levels, [doctoral student Annika] Axelsson and team note that some patients are unable to use them due to their severe side effects, which include kidney damage.
As such, there is a need for safer alternatives. Could sulforaphane meet this need? To answer this question, Axelsson and colleagues created a genetic signature for type 2 diabetes, based on 50 genes associated with the condition. The researchers then applied this signature to public gene expression data.
This allowed them to assess the effects of more than 3,800 compounds on gene expression changes in liver cells that are associated with type 2 diabetes. The team found that sulforaphane — a chemical compound present in cruciferous vegetables including broccoli sprouts, Brussel sprouts, cabbage and watercress — demonstrated the strongest effects.”
Sulforaphane Lowers Glucose Levels in Obese Diabetics With Poor Glucose Control
In tests using cultured liver cells, sulforaphane was shown to reduce glucose production. In diabetic rats, the compound improved gene expression in the liver. Next, they tested a broccoli sprout extract on 97 adults diagnosed with type 2 diabetes. All except three were also taking metformin.
After 12 weeks, patients with dysregulated diabetes who received a daily dose of broccoli sprout extract — containing an amount of sulforaphane equivalent to about 11 pounds (5 kilos) of broccoli — in addition to metformin had 10 percent lower fasting blood glucose levels than the placebo group. This is a significant enough improvement to reduce your risk of health complications, according to the authors, who described sulforaphane’s effects as follows:27
“Sulforaphane suppressed glucose production from hepatic cells by nuclear translocation of [Nrf2] and decreased expression of key enzymes in gluconeogenesis.
Moreover, sulforaphane reversed the disease signature in the livers from diabetic animals and attenuated exaggerated glucose production and glucose intolerance by a magnitude similar to that of metformin. Finally, sulforaphane, provided as a concentrated broccoli sprout extract, reduced fasting blood glucose and glycated hemoglobin (HbA1c) in obese patients with dysregulated type 2 diabetes.”
No effect was seen in patients whose diabetes was already well-regulated. According to the authors, broccoli extract may be a good complement to metformin, as the two compounds reduce blood glucose in very different ways. While metformin sensitizes your cells to insulin, thereby increasing cellular uptake of glucose (which reduces blood levels), sulforaphane acts by suppressing liver enzymes that stimulate glucose production.
For patients who cannot tolerate metformin, the supplement may be “an ideal substitute.”28 In future tests, the researchers will evaluate the effects of sulforaphane on people with prediabetes to see whether it might help prevent type 2 diabetes from developing in the first place.
Sulforaphane Also Combats Fatty Liver
As discussed in a recent Bulletproof blog post, the protein Nrf2 binds to antioxidant response element (ARE), a “master switch” that regulates antioxidant and glutathione production in your body. This helps explain why sulforaphane appears to offer such potent protection against chronic disease, as sulforaphane activates Nrf2.
In addition to combating diabetes and cancer, broccoli may also be an important dietary intervention for nonalcoholic fatty liver disease (NAFLD), which affects up to 25 percent of Americans,29 including children. NAFLD is defined as an excessive accumulation of fats in your liver in the absence of significant alcohol consumption.
The overconsumption of net carbs, especially fructose from processed foods, soda and juices, is strongly associated with NAFLD which, if left untreated, can raise your risk of liver cancer. Research30 suggests the fat-forming and pro-inflammatory effects of fructose may be due to transient ATP (the chemical storage form of energy) depletion.
This in turn leads to uric acid formation, which at excessively high levels acts as a pro-oxidant inside your cells. According to an animal study published in 2016, long-term consumption of broccoli may reduce your chances of developing fatty liver caused by the standard American diet by lowering triglyceride levels in your liver.31,32
Other Health-Promoting Compounds in Broccoli
Aside from sulforaphane, broccoli contains several other health-promoting nutrients and compounds, including:
• Fiber, which helps nourish your gut microbiome to strengthen your immune function and reduce your risk of inflammatory diseases.33 Fiber also activates a gene called T-bet, which is essential for producing immune cells in the lining of your digestive tract.34
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
• Glucoraphanin, a glucosinolate precursor of sulforaphane that influences carcinogenesis and mutagenesis.35,36 Compared to mature broccoli, broccoli sprouts can contain up to 20 times more glucoraphanin
• Phenolic compounds, including flavonoids and phenolic acids, which have a potent ability to eliminate damaging free radicals and quell inflammation,37,38,39 resulting in a lower risk for diseases such as asthma, type 2 diabetes and heart disease.40 One of the ways phenolic compounds slow the encroachment of disease is by defending against infection, most dramatically by zapping ROS linked to atherosclerosis and neurodegenerative diseases such as Parkinson’s and Alzheimer’s
• Diindolylmethane (DIM). Your body produces DIM when it breaks down cruciferous vegetables. Like many other broccoli compounds, DIM has shown multiple potential benefits, including boosting your immune system and helping to prevent or treat cancer41,42
• Nicotinamide mononucleotide (NMN), an enzyme involved in the production of nicotinamide adenine dinucleotide (NAD), a compound involved in mitochondrial health and energy metabolism. NAD may slow age-related decline in health by restoring your metabolism to more youthful levels.43,44,45
Previous research has shown that, with age, your body loses its capacity to create NAD — an effect thought to be related to, or the result of, chronic inflammation. Studies have also shown that taking NAD directly is ineffective. Instead, you’re better off taking its precursor, NMN, found in broccoli, cucumbers, cabbage, avocado and other green vegetables. Once in your system, NMN is quickly converted into NAD
Lightly Steam Your Broccoli to Boost Sulforaphane Content
When you eat raw mature broccoli, you only get about 12 percent of the total sulforaphane content theoretically available based on the parent compound. You can increase this amount and really maximize the cancer-fighting power of broccoli by preparing it properly.
In the video above, Professor Emerita Elizabeth Jeffery, a former researcher in the dietary mechanisms of cancer prevention at the University of Illinois, delves into this,46 which shows that steaming your broccoli for three to four minutes is ideal. Do not go past five minutes.
Steaming your broccoli spears for three to four minutes will optimize the 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. Without it, you cannot get any sulforaphane.
Boiling or microwaving your broccoli past the one-minute mark is NOT recommended, as it will destroy a majority of the myrosinase. If you want to boil your broccoli, blanch it in boiling water for no more than 20 to 30 seconds, then immerse it in cold water to stop the cooking process.
Adding Mustard Seed Can Maximize Sulforaphane Content Even Further
The sulforaphane content can be further optimized by adding a myrosinase-containing food to it.47 Foods containing this important enzyme include:
Adding a myrosinase-rich food is particularly important if you do not steam or flash-blanche raw broccoli. For example, frozen broccoli typically has a reduced amount of myrosinase as it’s already been blanched as part of the processing. Boiling or microwaving it further can easily lead to it being more or less devoid of sulforaphane. So, if you’re using frozen broccoli, be sure to add a food that contains myrosinase (see list above).
If you prefer raw food, you’d be better off eating raw broccoli sprouts instead of mature broccoli, as they’re a far more potent source of sulforaphane. Tests show three-day-old broccoli sprouts consistently contain up to 50 times the amount of anticancer compounds found in mature broccoli, including sulforaphane.49,50,51 This super-charged nutrient density means you can eat far less of them while still maximizing your benefits.