Is kale really a superfood? Its antioxidant is over 3x higher than iceberg lettuce, but the truth is that this gcruciferous leaf is mediocre, or at least comparable, when compared to other common salad greans like butterhead and red leaf lettuce (the latter of which has actually 30% higher antioxidant content than kale).
Is kale a lettuce or cabbage? It's actually a cabbage, which is a cruciferous vegetable (the same family as brocooli and cauliflower). Cruciferous contain unique phytonutrients which are not found in any other plants, so that means you shouldn't substitute kale entirely with lettuce. Ideally, have some of each in your food to get the best health benefits and antioxidant activity.
Verdict? Yes, kale is still considered a superfood. Even though its ORAC is average for a leafy green, it is jam packed with nutrients and vitamins. Just 1 cup (130 grams) of cooked kale provides you with 1,180% of your DRI of vitamin K, an important nutrient for bone health.
Research Support, Non-U.S. Gov't: Food Safety and Nutrition, Clemson University Literature (PDF) Revised Feb 2008