When I first encountered kale in real life, it was being munched on raw by a too-thin-to-be-healthy woman as her excuse for lunch. The unmistakable sulfuric air that commonly accompanies such cruciferous veggies soon followed. It’s easy to be a shallow judge and subsequently label kale as socially suicidal food for people who should consider befriending more calories. But here’s why the research says that kale can not only make you a social rockstar, but can insanely enhance your health as well!
6 of many reasons why kale is cool and can make you cool:
- It has potential anti-cancer compounds in it. Kale is stuffed with various antioxidants and most hugely a precursor to sulforaphane (check the references below to read more about this superhero), which may slow or prevent tumor growth and oxidative damage among other healthy actions. Yay!
- Troy Polamalu eats it. Troy is a badass, and is arguably the most energetic and exciting-to-watch defensive player in the NFL today*. If Troy eats it and is awesome, then if you eat it you could become awesome, too. http://lyfekitchen.wordpress.com/2012/08/21/training-tips-from-troy-polamalu/
- It has the potential to lower your cholesterol. Especially when you steam it, there’s these compounds that bind bile acids and take them into the toilet with them. Then, your liver has to make more bile acids to make up for the loss, which can lower your serum cholesterol. Excitement abounds!
- Kale is a test of true friendship. If someone doesn’t want to date you or invite you to movies because of the thank-you gift your gut bacteria give you for feeding them sulforaphane**, then tell them they don’t really care about you. How selfish to not think of you, your health, and the health of your bacteria in your gut which houses 70-80% of your immune system, but instead only care about their own temporary olfactory experience. Loser!
- It has good things for your eyesight, like lutein, and zeaxathin, which are carotenoids (yep, found in carrots, too!). A recent study found a decreased age-related macular degeneration risk with an increase in intakes of these two little oxidant fighters, and there are plenty of epidemiological studies that support the association as well.
- It’s got bunchloads of vitamins and minerals: Manganese (no, I didn’t make that word up!), Magnesium (yes it’s different than Manganese), Vitamin K, Vitamin C, Copper, and more players…We won’t go into why you need all of them in this blog. Some of the nutrients found in kale aren’t highly bioavailable (meaning that even though a lot of it is found in the food, it doesn’t get into our bodies***), but it’s still a nutritional powerhouse at the end of the day. Heating or cooking it in oil may enhance the absorption of some of these nutrients but hinder others (see below for more info), so vary your kale prep strategies.
OK, so, basically I bought it so I can be like Troy. And it looks like someone hacked it off a tree in Jurassic Park. How the heck do you eat this?
Well, it’s a trade off.
Blanching the stuff not only makes it taste less bitter, but it also was shown to improve the bile-acid binding capacity of it compared to either raw or sautéed. And sulforaphane in raw cruciferous veggies may not be as available due to the fact that two key ingredients needed to make it are too bound up. But heat may reduce the antioxidant activity coefficient for kale. (For other vegetables, heating can enhance this.) Just don’t over cook them, and don’t dump out your baby with the bath water, either (so steaming is better than boiling). The best bet is to vary how you eat it, occasionally raw, and occasionally steamed.
Can I win friends with it?
Sure! My guess is that rolling into parties with raw kale leaves would not increase your popularity immediately, though it may add that cute quirk factor you were going for. But here’s a few ways to say “I care” with kale.
Raw kale says “I like you the way you are: tough, crunchy, and without makeup.” Some stores sell baby kale leaves that are much easier to use as salad greens than their adult, more thick and intimidating counterparts. If you’re wary about showing your bitter side too soon, you may want to add something sweet like berries or apples to your salad to balance it out. If you don’t mind cleaning your blender, make this awesomeness mango dressing which goes perfectly with kale: http://www.champagnemango.com/recipe/mango-citrus-vinaigrette
For a warmer friendship-building tact, this is a nom-nom recipe for quinoa with kale and walnuts. It sends a clear message that you care about their heart (by enhancing the bile-acid binding capacity with the quick steam), but also that you want to get to know their whole person, unadulterated (quinoa is a whole grain, after all!).
If you’re a base-jumping risk-taker, show your wild side and use kale and walnuts instead of basil and pine nuts in pesto. People will be impressed with your bold moves. Pair it with a story about that time you smashed a spider with your thumb instead of toilet paper, and your Facebook page will explode with requests.
I’m always on the lookout for a new way to eat this stuff, and could obviously use friends, so if you have anything, share it!
MS, RD, PhD
* Troy is a strong safety stud for the Pittsburg Steelers.
** The sulfur gas response varies with individuals (we all have different ecosystems and activity levels of our bacteria). The fiber in the kale will help speed up some of the hang-time in your colon, so it may have less time to get consumed by your bacteria. Don’t let this deter you from pursuing good health unless you have an enhanced and unbearable response.
*** Bioavailability of nutrients will be a future blog.
Cooked or raw?
A nice study suggesting the different preparation methods of cruciferous veggies and their respective bile-acid binding capacities:
Kahlon, T.S., Milczarek, R.R., Chiu, M.M. (2012). In vitro bile acid binding of mustard greens, kale, broccoli, cabbage, and green bell pepper improves with sautéing compared with raw or other methods of preparation. Food and Nutrition Sciences, 3 (7), 951-958.
More info on cooking methods affecting antioxidant capacities on various veggies. Antioxidant Activity Coefficent can be unchanged, decrease, or increase with cooking. For Peppers, tomatoes, spinach, and onion, it’s increased; for broccoli shallots it’s not affected, but carrots and red cabbage can be reduced.
Sikora, E., Cieslik, E., Filipiak-Florkiewicz, A., & Leszczynska, T. (2012). Effect of hydrothermal processing on phenolic acids and flavonols contents in selected brassica vegetables. ACTA Scientiarum Polonorum Technologia Alimentaria, 11(1), 45-51
Myrosinase can hydrolize the glucoraphanin in cruciferous vegetables to produce sulforaphane, which is the anti-cancer and anti-microbial compound people get most excited about in these veggies. While studies have shown that myrosinase can be deactivated by cooking, it also has been shown to be too bound up with the glucoraphanin in raw broccoli. This study implies that it may still be hydrolyzed by gut bacteria to become sulforaphane, but it has been noted that those with major gastrointestinal conditions may lack the ability to do this effectively.
Lai, R., Miller, M., & Jeffery, E. (2010). Glucoraphanin hydrolysis by microbiota in the rat cecum results in sulforaphane absorption. Food and Function, 1, 161-166.
This study shows that for broccoli fresh may have a higher level of sulforaphane.
Conaway, C.C., Getahun, S.M., Liebes, L.L., Pusateri, D.J., Topham, D.K., Botero-Omary, M., & Chung, F.L. (2000). Disposition of glucosinolates and sulforaphane in humans after ingestion of steamed and fresh broccoli. Nutrition and Cancer, 38(2), 168-78. Erratum in Nutrition and Cancer 2001, 41(1-2): 196.
Scientists still do not have a complete understanding of the effects of the phytochemicals and cancer-protective agents in cruciferous veggies. However, here are some case-control studies that show a positive association:
Bosettie, C., Filomeno, M., Riso, P., Polesel, J., Levi, F., Talamini, R., Montella, M., Negri, E., Franceschi, S., & La Vecchia, C. (2012). Cruciferous vegetables and cancer risk in a network of case-control studies. Annals of Oncology, 23(8), 2198-2203.
And here’s a good study summarizing the in vitro and animal evidence for how compounds in cruciferous vegetables show anti-carcinogenic effects.
Herr, I., & Rausch, V. (2012). Sulforaphane as new therapeutic agent for targeting of cancer stem cells with focus to prostate and pancreatic cancer. Stem Cells and Cancer Stem Cells, 7(1), 27-32.