Kale Vs. Spinach -- The Great Debate

kale, spinach, vitamins, minerals, leafy greens, cruciferous vegetables, weight loss, inflammation, thyroid, goitrogen, gas, bloating, histamine, oxalic acid, detoxification

Dark, leafy greens are the epitome of "superfoods." They are rich in phytonutrients, antioxidants, vitamins, and fiber.  Dr. Mark Hyman, author of Food: What the Heck Should I Eat goes so far as to say that, "You should aim to eat them at every meal. Non-starchy vegetables like spinach, asparagus, broccoli, and kale should make up 50-75 percent of your plate."

We know that kale and spinach are nutritious, so what's the controversy? Well, for most of us, there is none. Eat more of them, be healthier. Plain and simple. But for some sensitive people or those with certain medical conditions, one may be preferential to the other.




Kale is a cruciferous vegetable and a member of the Brassica family. Other veggies in this family include broccoli, cauliflower, cabbage, bok choy, arugula, Brussels sprouts, and radishes to name a few.

Kale is rich in antioxidants and vitamins K, A, and C. Its caroteniods and flavonids are useful in protecting the body from oxidative stress and health problems like cataracts, atherosclerosis, and chronic obstructive pulmonary disease. Kale also contains compounds like glucosinolates and indole-3-carbinol, which have been shown to ward off cancer.

Other interesting tidbits ... kale can help to balance out estrogen levels, decrease blood sugars, reduce inflammation, and assist with weight loss. 

Possible Concerns

Those with thyroid disease are often told to avoid cruciferous vegetables. When eaten raw, these vegetables can release goitrogens, which may increase the need for iodine and can cause damage to the thyroid gland. There is some controversy over this, namely because it would require eating a lot of these types of vegetables to really have harmful goitrogenic effects. Cooking cruciferous vegetables reduces the amount of goitrogens. So, having a daily serving of cooked cruciferous veggies should not be an issue.

Another concern is the issue of gas and bloating after consuming kale and other similar vegetables. They contain raffinose — a sugar that remains undigested until bacteria in the gut ferment it, which produces gas and, in turn, causes bloating. A way around this is to, again, cook cruciferous vegetables. Limiting the serving size and frequency consumed may also be helpful.




Spinach belongs to the Amaranthaceae family, known sometimes as the Goosefoot family. Chard, beetroots, and quinoa are also in this family.

Spinach is extremely rich in vitamins A, K, and folate and in manganese. It has many anti-cancer carotenoids that have been found to provide significant protection against the occurrence of aggressive prostate cancer.  Studies have also shown that excessive inflammation decreases thanks to the these carotenoids. 

Other benefits of eating spinach include detoxification, regulation of blood sugar, vision maintenance, and preserved brain and heart health.

Possible Concerns

One downside of spinach is that it contains oxalic acid which, in some people, can bind with calcium potentially causing kidney stones. Excess oxalic acid is also responsible for gout, grittiness in the teeth, and sometimes anemia and poor mineral absorption. So, if you're prone to these issues, it may be best to avoid eating spinach.

Another issue is that spinach is high on the list of histamine-causing foods. When we think of histamines, we often think of allergies and allergic-type reactions like hives, runny nose, swelling in the throat, and itching. However, histamine reactions can be quite different for many people. On a personal note, when I eat spinach and other high histamine foods (like chocolate, avocado, and nuts), the rosacea on my face worsens. A histamine reaction can also trigger migraines, indigestion, nausea, and even low blood pressure. 

Final Thoughts

For the vast majority of people, upping your intake of kale and spinach is a great idea. The benefits of these leafy greens are too great to number. However, if you suffer from any of the above conditions, limiting the amount of these vegetables or choosing one over the other may be a good idea.


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