We all know that eating our broccoli is good for us, and many population studies have confirmed that people who eat more vegetables, and in particular broccoli and members of its extended family (the Brassicae), have better health and lower incidence of diseases such as cancer. The reasons for this have been under investigation for the past few decades, and it turns out that these homely veggies are marvels of the plant kingdom, conferring protection against many cancers and common degenerative processes through a variety of sophisticated biochemical mechanisms. The Brassica family includes not only broccoli, but also Brussels sprouts, cabbage, kale, cauliflower, bokchoy, arugula, radish, watercress and other vegetables. For those who have an interest in nutrition, you may know of the unique health benefits of the Brassica phytochemical indole-3-carbinol (I3C) which is metabolized in the body into the active compounddiindole-methane (DIM). I3C and DIM act as antioxidants, assist in detoxification of hormones and potentially cancer-causing substances, and are linked in research with health benefits for hormonal health problems, and prevention of certain cancers, such as lung, colorectal, breast and prostate cancer. Supplements which provide I3C and DIM have been available for years, and have been incorporated into the standard natural therapeutic approach for such health issues.
Super Sprouts
Now a “new” phytonutrient from the broccoli family is available in supplement form. In recent years, much scientific attention has been focused on Sulforaphane glucosinolate (abbreviated as SGS), a substance found in high concentration in broccoli seeds and sprouts (the sprouts contain 30 to 50 times the amount of SGS as mature broccoli). While SGS is found in other brassica vegetables such as cauliflower, kale, and cabbage, the greatest amounts by far come from broccoli. SGS was identified twenty years ago by researchers at The Johns Hopkins University School of Medicine as the most potent of the isothiocyanates, a class of beneficial compounds derived from certain Brassica vegetables. SGS was found to provide protection from chemical carcinogens by increasing levels of the Phase II liver detoxification enzyme squinone reductase and glutathione transferase, and powerful antioxidants such as glutathione and superoxide dismutase. What’s more, the antioxidant effects are extraordinarily long-lasting – as long as days after sulforaphane is in the picture, cells continue to have increased protection.
Subsequent and ongoing studies have found that sulforaphane, the active form of SGS, has multiple modes of action in the body, holds promise for cancer prevention and treatment, and has benefit for arthritis, cardiovascular protection, immune support, skin health, retinal health, and brain cell health. Without doubt, the list will continue to grow.
Sulforaphane and Cancer
In addition to preventing cancer by blocking the effects of carcinogenic compounds, sulforaphane is being studied for its benefit in treating several types of cancer. A recently published study performed at the University of Michigan on mice and on cultures of human breast cancer cells found that sulforaphane targeted and killed breast cancer stem cells, a small number of cells within tumors which drive the growth and spread of the cancer. Because tumor stem cells permit cancers to recur after treatment and metastasize, and because they are so small in number (approximately one cell in a million is a stem cell), the effectiveness of sulforaphane in finding them, reducing their number and their ability to create new tumors – without significantly affecting healthy cells – is a truly groundbreaking finding.
In other areas of cancer research, studies have found that sulforaphane reduces stomach levels of the bacterium H. pylori, an infectious organism which causes chronic stomach inflammation, increases incidence of gastric and duodenal ulcers, and risk for stomach cancer. It has been shown in multiple studies to cause death of prostate cancer cells and, in an animal study, to reduce incidence of bladder cancer by more than half. In combination with resveratrol, (the antioxidant found in grapes, berries, and red wine), it has been found to inhibit the cell replication and survival of glioma, the most aggressive form of brain cancer. Studies on colon, lung, pancreatic and leukemia cell lines have shown inhibition of important steps in the replication processes of cancer cells.
Anti-Inflammatory Action
The same mechanism (the Nrf2 protein signaling pathway) by which sulforaphane increases the activity of liver detoxification enzymes also has powerful anti-inflammatory effects, and in addition to reducing generalized body inflammation, research is suggesting a role for sulforaphane in treating rheumatoid arthritis, through reduction in the level of rheumatoid T cells; osteoarthritis, by interfering with enzymes that destroy joint cartilage; and asthma, chronic obstructive pulmonary disease, allergic rhinitis, and other inflammatory respiratory conditions, by means of its antioxidant effects.
Nrf2, Your Arteries, and Your Brain
This same protein, Nrf2, whose activity is increased by sulforaphane, has been shown to protect blood vessels from atherosclerotic plaque buildup in areas where they are most vulnerable to it. Other studies find that this sulforaphane/ Nrf2 pathway protects brain cells from free radical damage and inflammation, with possible benefits for neurologic diseases such as Parkinson’s and Alzheimer’s disease.
Sunscreen from Broccoli?
While it’s true that ultraviolet radiation (UVR) is considered to be the primary cause of skin cancer, the most common cancer in the U.S., the question of what the health-conscious person can do to protect themselves and their children against UVR has become a knotty one. To quote the Environmental Working Group’s Sunscreen Guide, “The best sunscreen is a hat and a shirt.” This is because of the array of toxic and carcinogenic chemicals (many of which are associated with increased risk of skin cancer!) that are present in just about all commercially available sunscreens (the exceptions use zinc or titanium as UV blockers). To complicate matters, Vitamin D formation in the skin is blocked by sunscreen, and this nutrient is just about impossible to obtain in optimal doses otherwise, except through supplementation.
So the research discovery that sulforaphane in a topically applied broccoli sprout extract both protects skin cells (for days after exposure) from the damaging effects of UVR and reduces the inflammation that can cause precancerous skin cells to become cancerous is important and exciting. Even better, it does this without interfering with Vitamin D production in the skin. While it may be awhile before “sulforaphane sunscreen” is commercially available, it makes sense that keeping sulforaphane levels high within the body should create healthier skin – and given the recognized association between UVR damage and aging effects on skin, increasing intake of sulforaphane could be part of an anti-aging strategy as well.
How Much Broccoli?
By now you must be saying, “Show me the broccoli!” But how much broccoli do you have to eat to get a decent amount of sulforaphane? Between one and two pounds a day of raw broccoli will provide you with the recommended 50-100 mg daily dose of SGS, which should then convert into 2000-4000 mcg of active sulforaphane in the body. The broccoli must be raw, because sulforaphane is largely inactivated by cooking; it should be noted also that the SGS content of broccoli varies widely. There is a product coming into stores called “Brocco Sprouts” (www.broccosprouts.com), which are packaged broccoli sprouts. About 1 ounce (½ cup) is considered a serving, and one to two servings a day would approximate the SGS levels noted above. (By the way, I have no affiliation with the company.)
SGS supplements have been available for a few years. High quality products are standardized to provide about 50 mg of SGS per capsule from 500 mg of broccoli sprouts and/or seed, one or two capsules per day (divide the dose if taking two) is a typical recommendation.
A few additional considerations: 1) because SGS and Sulforaphane improve Phase II detoxification, there could be an increase in metabolism of some pharmaceutical medications. However, there have not been noted drug interactions or toxic effects in safety studies; 2) SGS is metabolized into its bioactive form, sulforaphane, by the act of chewing, and to some extent by probiotic microorganisms (bacteria) in the digestive tract; 3) there may be a synergistic effect between sulforaphane and the trace mineral selenium. So it could be a good idea to take a high-quality probiotic, and evaluate your diet and supplements for selenium sufficiency, to get the most benefit from sulforaphane.
Debra Gibson, N.D. practices naturopathic family medicine in her Ridgefield, CT office. She can be reached at 203-431-4443 or at [email protected].