best protein powder for building muscle casein slow digesting Optimum Nutrition
[{'entity': 'CORE_PRODUCT_TYPE', 'value': 'protein powder', 'span': [5, 19]}, {'entity': 'OCCASION', 'value': 'for building muscle', 'span': [20, 39]}, {'entity': 'MATERIAL', 'value': 'casein', 'span': [40, 46]}, {'entity': 'ATTRIBUTE', 'value': 'slow digesting', 'span': [47, 61]}, {'entity': 'BRAND', 'value': 'Optimum Nutrition', 'span': [62, 79]}]
best protein powder for building muscle casein slow digesting Optimum Nutrition