The Dark Side of Kale: What You Need to Know Before Going Crazy on Kale

Mechele R. Dillard's picture

Kale is undoubtedly healthy for many of us, but there are some negatives associated with this superfood, and you should be aware of those before making kale a mainstay of your daily diet.

Kale is the current “superfood” at the top of everyone’s must-eat list. It is being thrown into salads, used in recipes instead of spinach and collards, and even baked into chips. But, as good as kale is for you, there are also health considerations one must be aware of before going crazy on kale.

Web M.D. indicates that kale is bursting with nutrition, and is possibly a positive force in cancer protection and lowering cholesterol. Kale is a cruciferous veggie, similar to cabbage, broccoli, collard greens or Brussels sprouts—not all known as well-loved veggies, but healthy nevertheless. Still, when it comes to health benefits, kale is thought of by many to be a healthy veggie among healthy veggies. According to Web M.D., the health benefits are enormous:

One cup of kale contains 36 calories, 5 grams of fiber, and 15% of the daily requirement of calcium and vitamin B6 (pyridoxine), 40% of magnesium, 180% of vitamin A, 200% of vitamin C, and 1,020% of vitamin K. It is also a good source of minerals copper, potassium, iron, manganese, and phosphorus.

Wow! Additionally, kale is also an excellent source of antioxidants, including the already-mentioned vitamins A, C, and K. And, Web M.D. points out, kale is rich in the carotenoids and flavonoids that have been associated with anti-cancer health benefits.

What Could Be Wrong with Kale?

Vitamin K is a particularly important vitamin found in kale. Web M.D. points out that a study in the American Journal of Clinical Nutrition indicated that vitamin K reduces the overall risk of developing or dying from cancer. It is necessary for blood clotting and bone health, as well. However, Web M.D. also points out that those taking anticoagulants such as warfarin could find that the high level of vitamin K could interfere with their medication and, therefore, should consult with their personal physicians before adding kale to their diets.

Another potential problem with eating large amounts of kale, Web M.D. indicates, is the oxalates found in the veggie. These naturally occurring oxalates can interfere with the absorption of calcium. Therefore, Web M.D. advises, calcium-rich foods should not be eaten at the same time as kale.

Overall, kale does appear to deserve its status as “superfood.” And, whether you like it raw, lightly steamed, or cooked into chips, most people can likely add it to their diets safely. However, like any health craze, it is important to be aware of the potential negatives and consult your doctor before going kale-crazy, particularly if you take an anticoagulant or if you have calcium-absorption issues.

For more information about kale, visit Web M.D.

Image: Wikimedia Commons


Submitted by Barbara Murphey... (not verified) on
after you read this story you are left with what is this woman trying to say because the only "dark side" of this expose on kale is that it may interfer with some med users or that it may not be good to eat it with other calicum foods so what? it say nothing other than to create a dark side claim when there's no dark side issues offered a waste of time for people who enjoy kale, I think

I disagree. The negatives of kale are rarely discussed by those who push this so-called "superfood," and they are, in my opinion, a darkside to the leafy green. "So what?" is fine if you have none of these issues, but if you do and are subsequently affected by a problem that could have been avoided had you known that it existed, you might not be so eager to call the obvious darkside a "waste of time." Thank you, however, for your comment.

Submitted by Drew Ramsey MD (not verified) on
Kale is very low in oxalates and really only a problem for patients taking Coumadin. Please fact check before you spread misinformation of this great superfood Drew Ramsey, MD co-author 50 Shades of Kale

You are correct, Dr. Ramsey, in that the article should have stated, as did Web M.D., that kale <em>contains</em> oxalates, not that it is <em>high</em> in oxalates. However, as oxalates do have the potential to interfere with the absorption of calcium, it still is a concern that may be taken into consideration by those having an issue with calcium absorption. And, those with the health concerns mentioned should still see their doctor before adding kale to their diets.

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