“Any vegetable that has a very deep color the way kale does, that means there is a high concentration of nutrients, and that translates into a range of antioxidant and anti-inflammatory effects in the body,” says Deirdre Orceyre, a naturopathic physician at the Center for Integrative Medicine at the George Washington University Medical Center.
This wide array of vitamins, nutrients and minerals results in several documented, distinct health advantages.
“Brassica vegetables are known to help with general health as well as heart disease and cancer, but even among this group kale stands out” because it has the broadest range of antioxidants and also the highest levels of several specific ones, along with Vitamin K and a type of Vitamin E that seems to be heart-healthy, Harris says. It has been shown to lower cholesterol and may reduce the risk of certain types of cancer, although there is evidence that a person’s specific genetic makeup also comes into play. A new laboratory study also found that kale extract inhibits the production of existing colon cancer cells.
Orceyre highlights the fact that the green contains indole-3- carbinol, a nutrient that seems to play a role in how estrogen is metabolized in the body and may play a protective role against breast cancer. “We sometimes use it as a supplement in patients with breast cancer, anyone who has a reason to be concerned about developing breast cancer and for those with estrogen-dominant illnesses like fibroids, fibrocystic breast disease or endometriosis, to try to help modulate negative estrogenic effects in the body,” she says. “Eating kale is a natural way to do that.”
Meanwhile, the fiber in kale can aid digestion in general, says Baltimore dietitian Angela Ginn, a spokeswoman for the Academy of Nutrition and Dietetics. Eating kale, she says, “revs up your body’s natural detoxification ability.”
Still, it’s probably best not to go overboard with kale and to simply integrate it into an overall healthful diet full of other fruits and vegetables.
“There are a couple of controversial things about kale that are worth mentioning,” says Orceyre, who explains that its large concentration of Vitamin K can be a problem for people taking blood thinners and other medications because it promotes clotting; the green also contains oxalates, which in lab tests have been associated with kidney stones and some gallstones.