It’s not always easy to eat the right things. So when you fill your plate with wholesome foods, it pays to make sure you’re choosing the most nutritious ones. Romaine lettuce is good for you, for example, but swapping it for one of the even more nutritious dark, leafy greens, like spinach or kale, is even better. Some foods, after all, are true nutritional powerhouses, with more vitamins, minerals and disease-fighting antioxidants than others.But a “superfood” doesn’t deserve that status if it’s too expensive or difficult to find, says Wendy Bazilian, RD, co-author of Superfoods Rx Diet: Lose Weight with the Power of Supernutrients (Rodale Books).