https://www.chameleonforums.com/care/food/
"Best - These gutloading ingredients are best because they are highest in calcium, low in phosphorus, oxalates and goitrogens. They should be the primary components of your gutload: mustard greens, turnip greens, dandelion leaves, collard greens, escarole lettuce, papaya, watercress and alfalfa.
Good - These gutloading ingredients are good because they are moderately high in calcium and other vitamins/minerals. They should be used in addition to those from the previous category: sweet potato, carrots, oranges, mango, butternut squash, kale, apples, beet greens, blackberries, bok choy and green beans."