Kale has been imbued with a health halo. It’s often termed a super food because it contains a cornucopia of nutrients. But for same, kale also has its downsides.
The Good News About Kale
While eating kale won’t counteract a steady diet of burgers and fries, there are a lot of compelling reasons to add the rich leafy green to your diet.
One cup of kale contains only 36 calories, while supplying 7.2 grams of filling fiber. Research shows that eating this cruciferous vegetable may also help control diabetes, protect against age-related eye disease, keep inflammation at bay and strengthen your bones.
Kale chips, in particular, are packed with dietary fiber, vitamin K and omega-3 fatty acids (an essential fatty acids that the body requires but can’t produce itself) that aid in controlling blood sugar levels. They’re also low in calories and carbohydrates.
But Too Much Kale Can Be Harmful
Don’t assume that because kale is loaded with vitamins and minerals that more is necessarily better. Too much of a single food can get you in as much trouble as too little, which is why I preach moderation. Here are the downsides to eating too much kale:
1. Gastrointestinal problems, such as bloating and gas.
For some of us, kale’s high levels of insoluble fiber result in an overburdened digestive system, which causes bloating, gas and flatulence.
One cup contains a whopping 5.1 grams of insoluble fiber, the type that doesn’t dissolve in water, and passes directly through the digestive system intact. While insoluble fiber is good, too much is not so good. And, if you suffer from irritable bowel syndrome (IBS), you’re probably better off avoiding kale altogether.
A recent study of Meals on Wheels patrons highlighted the digestive problems many older bodies have breaking down this chewy vegetable: “The Brassica genus of vegetables (which includes kale, as well as Brussels sprouts, cauliflower, broccoli and cabbage) was not perceived to be well tolerated. Severe gastrointestinal symptoms of intolerance, such as diarrhea and nausea/vomiting, were infrequently experienced.”
2. Drug interaction with Warfarin (Coumadin).
Many older adults take Warfarin or Coumadin to reduce the risk of stroke, heart attack or deep vein thrombosis. The purpose of this blood thinner is to reduce the risk of developing blood clots. Vitamin K is a nutrient that promotes blood clotting, and kale contains a mega dose (along with spinach, broccoli and brussel sprouts). If you’re taking medication to prevent blood clots, be wary of neutralizing it by eating too much kale.
The American Heart Association cautions that eating foods high in vitamin K can make the drug less effective, leading to an increased risk of a blood clots. And one food-drug interaction study warned that eating large amounts of vegetables rich in vitamin K could also interfere with the effectiveness and safety of Warfarin therapy.
3. Potential hypothyroidism.
According to the American Thyroid Association, over 12% of the US population will develop a thyroid condition during their lifetime. Women, especially those over 60, are the most likely to develop hypothyroidism, a condition in which your thyroid gland doesn’t produce enough of certain important hormones. This causes your basal metabolic rate to slow down, which frequently results in weight gain.
Whether eating kale might cause or exacerbate hypothyroidism has drawn much debate, and there is some reliable evidence to support this conclusion. Angela M. Leung, MD, an endocrinologist and clinical assistant professor of medicine at UCLA David Geffen School of Medicine and chair of the Public Health Committee at the American Thyroid Association, has studied this issue. She explains that the thyroid gland needs iodine to produce its hormones and that kale contains “thiocyanate, which in very high concentrations, can interfere with adequate iodine nutrition,” and potentially cause hypothyroidism.
However, this effect can be minimized by cooking the kale. And, as Dr. Leung believes, as long as you don’t make kale a prominent daily staple, the risk is fairly minimal.
