Kale is one of those previously overlooked foods that’s presently enjoying its time in the spotlight. In fact, the attention paid to kale in recent years has arguably approached the level of dietary fad—or national obsession. So why did kale emerge from the health food bargain bin to become the go-to ingredient that trendy foodies, chefs, home cooks, and food magazine publishers can’t seem to get enough of?
Natural Cancer-Fighting Compounds Abound
For starters, kale probably deserves at least some of the attention it’s received. As a member of the cole family of vegetables, which also includes well known healthy superfoods, such as broccoli and cauliflower, kale was due for a makeover, if not a reintroduction. That’s because, like the other cole crops (also called cruciferous vegetables), kale is a humble leafy green that is a potent source of unique chemical compounds that may confer outsized health benefits.
Among many other potential benefits under ongoing investigation, kale contains compounds, called glucosinolates, and sulforaphane, which have demonstrated potent anti-cancer activity in laboratory studies. As of 2013, scientists had identified more than 130 different glucosinolate compounds in this family of superfoods. In addition to these biologically active compounds, kale contains significant amounts of vitamin C, soluble fiber, and the anti-cancer trace element, selenium.
Kale and other cabbage-family vegetables (also known as Brassica vegetables) also contain compounds such as indole-3-carbinol, which has been shown to boost cellular DNA repair, at least under laboratory conditions, and to inhibit the growth of cancer cells. Once in the body, gut bacteria convert this beneficial compound into yet another compound, called 3,3′-Diindolylmethane (DIM), which appears to exert its own anti-cancer effects in the body.
Among other possible mechanisms of action to explain these highly beneficial effects, recent research showed that DIM selectively inhibits cancer stem cells. That means it leaves healthy cells alone, and only targets progenitor cells that go on to become cancer cells. Furthermore, DIM rendered growing, mature cancer cells far more susceptible to the effects of common chemotherapy drugs, even after the tumor-producing cells had developed resistance to the potent drugs.
In fact, this remarkable activity by I3C and DIM has prompted some scientists to suggest that these Brassica compounds should be considered for inclusion in chemotherapy regimens that until now have relied solely upon pharmaceuticals approved for combatting cancer. As noted in the medical journal, Cancers, in an article published in 2011, “…an equally intriguing property of these compounds is their ability to sensitize cancer cells to standard chemotherapeutic agents. Such chemosensitizing effects of indole compounds can potentially have major clinical implications because these non-toxic compounds can reduce the toxicity and drug-resistance associated with available chemotherapies.”
Kale is just the latest Brassica family vegetable to enjoy its moment in the nutritional spotlight. And just like its Brassica cousins, kale deserves the attention. Research shows that diets rich in Brassica vegetables may be linked to reduced risks of various serious illnesses, including some of the most common forms of cancer. So, while the kale craze may have taken things a bit too far with items such as kale ice cream, there’s no good reason to avoid this trendy vegetable. It’s excellent sautéed, baked, or eaten raw in salads.