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PHYTOCHEMISTRY

& HEALTHSPAN

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Frequently asked questions

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You and others frequently call sulforaphane an indirect antioxidant.  What does that mean?


Oxidative stress is thought to be at the root of many diseases and pathologies OR to be a consequence of those conditions OR both. Many classic antioxidants (e.g. vitamin C, tocopherols or vitamin E, and beta carotene) act directly by terminating chain reactions initiated by free radicals or by directly quenching oxidants or reactive oxygen species. These are direct antioxidants – they directly, and sacrificially prevent oxidation. In contrast, sulforaphane induces or up-regulates a very wide range of protective enzymes in the body. Many of these are directly involved in countering oxidative stress. These include the enzymes controlling production of the body’s most ubiquitous and concentrated antioxidant, glutathione (or GSH). Sulforaphane does not directly quench or inhibit oxidation since it does not have what chemists call “redox activity”. Rather, it enhances and increases many [direct] antioxidants that in turn protect cells from oxidative stress. Thus, we call sulforaphane an indirect antioxidant. The immediate and direct antioxidant power of one serving of broccoli sprouts is similar to one serving of orange juice, green tea, or blueberries (0 days; left panel). One day later, sulforaphane-rich broccoli sprouts are very powerful indirect antioxidants (8 million units per serving; right panel). In contrast, the other foods retain only very weak indirect antioxidant activity (thousands of units per serving). Notably, broccoli sprouts still retain one half of their high indirect antioxidant potency, even 96 hours later.




You say that sulforaphane bioavailability can be estimated by measuring the sulforaphane and its metabolites (DTCs) excreted in the urine collected over 24 hours from people. What DTC urinary excretion have you historically seen in the following scenarios: giving sulforaphane (SF) alone, giving glucoraphanin (GR) alone, and giving GR with an active myrosinase enzyme source? Is there great person-to-person variability in those numbers?


70% (SF), 10% (GR), 35% (GR + active myrosinase) And, Yes. It has to do both with our innate metabolism (as a result of our genetics) and the metabolism of our unique gut microbiome (the bacteria that colonize our gastrointestinal tract).




Are there good sulforaphane supplements and bad ones?


Absolutely! However, we have only tested a small fraction of the hundreds of supplements that represent themselves as containing meaningful amounts of sulforaphane or sulforaphane-producing compounds — SF, GR, GR + myrosinase, broccoli, broccoli sprouts, or broccoli seeds. Remember that GR (glucoraphanin) plus active myrosinase (an enzyme) produces SF (sulforaphane).




I am fighting bladder cancer, and I am interested in exploring ways to prevent or delay a recurrence. I viewed your presentation, “Development of Sulforaphane as a Nutritional Supplement,” and I see promise in a dietary approach to prevention. Can you comment?


Mustardseed powder has been used in traditional Chinese medicine, Ayurvedic medicine, and other traditional and folk medicines for millennia. Mustard is a cruciferous plant, and its seeds are among the richest known sources of allyl isothiocyanate. Work in our lab has demonstrated that pure allyl isothiocyanate selectively targets human bladder cancer cells via the urine, spares normal human bladder epithelial cells, and inhibits bladder cancer development and muscle invasion in a rat bladder cancer model. In light of human bladder tissue’s unique exposure environment, bladder cancer occurs in what may be one of the best candidate tissues for a therapeutic and perhaps a preventive approach that employs dietary isothiocyanates. Shortly after their consumption, isothiocyanate compounds and their conjugates build to very high concentrations exclusively in the urinary bladder and, therefore, are able to exert their selective activity against tumor cells in the bladder epithelium. A study we published in Carcinogenesis in 2010 showed that in a rat bladder cancer model, not only was bladder cancer growth markedly inhibited, but all muscle invasion was blocked, and key proteins involved in cell growth, division, and death were significantly modulated by dietary mustard seed powder – possibly the perfect storm against bladder cancer. Although the study was conducted using the predominant isothiocyanate found in mustardseed, we believe that the conclusions may apply equally to sulforaphane from broccoli sprouts and to moringin from Moringa oleifera. Sources:
Bhattacharya A, Y Li, KL Wade, JD Paonessa, JW Fahey , Y Zhang. (2010) Allyl isothiocyanate-rich mustard seed powder inhibits bladder cancer growth and muscle invasion. Carcinogenesis 31(12): 2105-2110. Fahey JW . (2010) Beyond the Abstract – Allyl isothiocyanate-rich mustard seed powder inhibits bladder cancer growth and muscle invasion. UroToday . November 5, 2010. (www.urotoday.com).




You and others frequently call sulforaphane an indirect antioxidant.  What does that mean?


Oxidative stress is thought to be at the root of many diseases and pathologies OR to be a consequence of those conditions OR both. Many classic antioxidants (e.g. vitamin C, tocopherols or vitamin E, and beta carotene) act directly by terminating chain reactions initiated by free radicals or by directly quenching oxidants or reactive oxygen species. These are direct antioxidants – they directly, and sacrificially prevent oxidation. In contrast, sulforaphane induces or up-regulates a very wide range of protective enzymes in the body. Many of these are directly involved in countering oxidative stress. These include the enzymes controlling production of the body’s most ubiquitous and concentrated antioxidant, glutathione (or GSH). Sulforaphane does not directly quench or inhibit oxidation since it does not have what chemists call “redox activity”. Rather, it enhances and increases many [direct] antioxidants that in turn protect cells from oxidative stress. Thus, we call sulforaphane an indirect antioxidant. The immediate and direct antioxidant power of one serving of broccoli sprouts is similar to one serving of orange juice, green tea, or blueberries (0 days; left panel). One day later, sulforaphane-rich broccoli sprouts are very powerful indirect antioxidants (8 million units per serving; right panel). In contrast, the other foods retain only very weak indirect antioxidant activity (thousands of units per serving). Notably, broccoli sprouts still retain one half of their high indirect antioxidant potency, even 96 hours later.