In plants it’s the same, and plant species are grouped into ever larger groupings. The genus Moringa is the only genus in the family Moringaceae (this is unusual- most families have multiple genera), and Moringaceae is in turn grouped into a large group called the Order Brassicales. The family that Moringaceae is most closely related to is Caricaceae, the papaya family. Caricaceae+Moringaceae is then only distantly related to the other families in the Order, which include Brassicaceae, the Mustard Family, Capparaceae, the Caper Family, Tropaeolaceae, the Nasturtium Family, and a bunch of other odd and interesting families scattered around the world.
What almost all of these families have in common is that they produce mustard oils, or glucosinolates. They seem to be defense compounds that help protect plants from insects and other animals that would want to eat them, protection via what has been nicknamed “the mustard oil bomb.” The mustard oil bomb works as follows. Brassicalean plants sequester glucosinolates in some cells, and an enzyme (enzymes are busy proteins that perform tasks) called myrosinase in other cells. When an insect or other herbivore (you, for example), bites into the plant, the enzyme is mixed with the glucosinolates. The enzyme cleaves the glucosinolate molecules and liberates a spicy tasting compound known as an isothiocyanate.
Studying these molecules is delicate work because they are very fragile and it’s easy to destroy them while handling and in the scientific instruments used to detect them. My friend and admired colleague Jed Fahey, of the Cullman Chemoprotection Center of Johns Hopkins University School of Medicine, is an expert on these compounds and has developed careful techniques to extract them and study them. More on his work in a moment. For now, I wanted to show you a figure modified from our paper Olson and Fahey (2011) with some of the main glucosinolates and isothiocyanates in Moringa. Notice that no matter how complex, you can always find the N=C=S groups.
Jed has been studying the role of isothiocyanates in dealing with cancer for over 20 years. Using a standardized method based on cultured mouse liver cells, he has assayed the ability of a large number of plants to boost the body’s early tumor detection and deactivation system. The body has a vast battery of metabolic tricks for dealing with challenges from the environment. Many of these challenges involve damaging molecules entering the body in food, air, or water. Many of these find their way to the liver, where they are converted into other molecules for disposal. There are several steps in the processing of a toxin. Often the first step, which helps to latch on to a toxin molecule and make it more easy to process, as via solubility adjustment, actually makes the molecule more rather than less toxic. This is where what are known as Phase 2 detoxification enzymes come in. Enzymes are proteins that catalyze reactions. Phase 2 enzymes further process the molecules, reducing their toxicity and also making them easier to excrete. High levels of Phase 2 enzymes mean that molecules that would otherwise cause mutations or encourage runaway cell proliferation (tumors) are disactivated and excreted.
Thanks to Jed and his colleagues, the isothiocyanate called sulforaphane is the most potent inducer documented to date of Phase 2 enzymes. Sulforaphane does not cure cancer, but is has been proven to help prevent cancer (see for example Talalay et al. 1995, Fahey and Talalay 1999, Shapiro et al. 1998, Fahey et al. 2002, Cornblatt et al. 2007, among others). Cancer is hard to treat, because the cancer stem cells that give rise to new tumors are very resilient, like all stem cells, and the survival of just a few of cancer stem cells is enough for a cancer to persist in the body. As a result, attention is being drawn to preventing cancer just as much as it is to treatment of cancer. A central tool in cancer prevention is the ingestion of substances in the diet that help to prevent cancer. Because it involves chemicals that help prevent cancer, this dietary protection is known as cancer chemoprevention. Happily, it’s easy to get sulforaphane in your diet: 3 day-old broccoli sprouts of certain broccoli varieties seem to have the highest concenctrations of sulforaphane anywhere in nature. There are even brands of broccoli sprouts you can buy with guaranteed levels of sulforaphane in them. What sets sulforaphane apart from moringa is that it has been subject to various clinical trials, that is, detailed studies in human subjects. So when you see information that a given amount of sulforaphane produces a given effect in humans, this is based on very solid data.
There have been no clinical trials on cancer and moringa. However, broccoli sprouts and sulforaphane are hard to get in most of the tropics, so there is considerable interest in moringa around the world. In what follows, I will give you an idea of what is known about moringa and cancer and what it means for how you should consume moringa.
Moringa has been reportedly used for treating tumors in traditional Indian medicine for thousands of years (Hartwell 1967-1971). This use prompted Jed and his lab to study the possible cancer chemoprotective activity of compounds in Moringa. In studies in cultured mouse liver cells, they found that 4-(4'-O-acetyl-α-L-rhamnopyranosyloxy)benzyl isothiocyanate and the related compound niazimicin strongly inhibited antigens related to certain cancer types (Fahey et al. 2004, Guevara et al. 1999, Murakami et al. 1998). These studies were conducted in cells cultured in Petri dishes, but what about in live animals? These studies also seem to show potent anti-cancer activity. In one study, Murakami et al. (1998) fed a potent carcinogen to two groups of mice. One group received moringa leaf plus the carcinogens whereas the control group received only carcinogens. The control group was plagued with tumors whereas the one that received moringa showed a drastically lower tumor rate. Similarly, in a study that included a more complex series of controls, Bharali et al. (2003) found that moringa consumption helped lower skin cancer rates. Studies to date thus strongly suggest that moringa, specifically Moringa oleifera, offers a very useful tool in cancer chemoprevention in the tropics. Because the active compounds in both moringa and broccoli sprouts are isothiocyanates, it is reasonable to think that some compound in moringa should act in a way analogous to sulforaphane. It is even possible that a compound in some Moringa species will be found to be a comparable or even more potent cancer chemopreventive agent than sulforaphane, offering low-cost cancer chemoprevention for people, even poor ones, in the tropics worldwide.
Given that laboratory studies and tradition show moringa to be useful in cancer prevention, but that there are as yet no clinical trials that tell us how much to ingest, what should you and your family do? The answer with moringa is always the same: eat it as a nutritious vegetable in your daily diet. This is because the minimum dose for chemoprevention is not known. So, to hedge your bets, eat moringa in nutritionally relevant quantities. This will almost certainly meet or exceed the minimum dose needed for chemoprevention. It might be that a moringa capsule a day is enough for receiving chemoprotective benefits, but there is at this point no way of knowing this. What we do know with certainty is that a generous helping of lightly cooked moringa leaves a day is a yummy and nutritious addition to your diet. If you live in a dry tropical community, then it is also a very inexpensive one. Remember, when you think about how you should be eating moringa, you should think about spinach, chard, kale, and other leafy vegetables, NOT taking moringa in pills or other medicine-like forms. Moringa is a food, not a medicine. People have been eating moringa as a vegetable in just this way for thousands of years and we know that it provides protein and vitamins with virtually no “side effects” (see my post on moringa side effects). The leaves, and possibly the young fruits, seem to contain the compounds of interest, not the seeds. Eating moringa leaves as a vegetable is nutritious and safe, and seems likely to meet or exceed the dose needed for also enjoying the cancer chemoptrotective effects of the plant. This is what seems likely given what is now known about the plant, and this is what we do at my house. We eat moringa as a vegetable daily if we can.
Does moringa help treat and not just help prevent cancer? Because Phase 2 enzymes act by deactivating carcinogens, consumption of moringa in a case of cancer could help to avoid further independent tumors, and eating a nutritious vegetable is always helpful. However, it remains to be seen whether there is any reason to think that any compound in moringa could have an effect on existing tumors.
The International Moringa Germplasm Collection is designed to facilitate studies on the applied properties of Moringa. We are hoping to secure funding for the expensive studies necessary to assay the entire diversity of cancer chemoprotective activity across the genus. If we can find a compound equal or even more potent than sulforaphane, then moringa might become the broccoli sprouts of the tropics, offering low-cost cancer chemoprevention to the poor to whom such compounds have been largely inaccessible.
Fahey, J. W., & Talalay, P. (1999). Antioxidant functions of sulforaphane: a potent inducer of Phase II detoxication enzymes. Food and Chemical Toxicology, 37(9), 973-979.
Fahey, J. W., Haristoy, X., Dolan, P. M., Kensler, T. W., Scholtus, I., Stephenson, K. K., ... & Lozniewski, A. (2002). Sulforaphane inhibits extracellular, intracellular, and antibiotic-resistant strains of Helicobacter pylori and prevents benzo [a] pyrene-induced stomach tumors. Proceedings of the National Academy of Sciences, 99(11), 7610-7615.
Fahey, J.W., A.T. Dinkova-Kostova, K.K. Stephenson, and P. Talalay. 2004. The ‘‘Prochaska’’ Microtiter Plate Bioassay for Inducers of NQO1. Methods in Enzymology 382: 243-258.
Guevara, A. P., C. Vargas, H. Sakurai, Y. Fujiwara, K. Hashimoto, T. Maoka, M. Kozuka, Y. Ito, H. Tokuda y H. Nishino. 1999. An antitumor promoter from Moringa oleifera Lam. Mutation Research 440: 181-188.
Murakami, A., Y. Kitazono, S. Jiwajinda, K. Koshimizu y H. Ohigashi. 1998. Niaziminin, a thiocarbamate from the leaves of Moringa oleifera, holds a strict structural requirement for inhibition of tumor-promoter- induced Epstein-Barr virus activation. Planta Medica 64: 319-323.
Shapiro, T. A., Fahey, J. W., Wade, K. L., Stephenson, K. K., & Talalay, P. (1998). Human metabolism and excretion of cancer chemoprotective glucosinolates and isothiocyanates of cruciferous vegetables. Cancer Epidemiology Biomarkers & Prevention, 7(12), 1091-1100.
Talalay, P., Fahey, J. W., Holtzclaw, W. D., Prestera, T., & Zhang, Y. (1995). Chemoprotection against cancer by phase 2 enzyme induction. Toxicology letters, 82, 173-179.