My iguana wont touch its food

for about 3 or 4 days now my iguana stopped eating from its food bowl its fairly new and i can take it out of its cage and hand feed it collard greens mustard greens and another kind they came mixed together in a bag and he just nibbles on it doesnt realy eat at it just takes the tiniest bits and leaves it alone but the current veges and fruits in his bowl are the greens pea pods green beans gs and bell pepper i bought a book and all of these are reccomended foods so why wont he eat them?