Casein is a type of protein found in milk and milk products. In people with milk allergies, casein may be the culprit. The protein sometimes shows up in unsuspected products, so awareness is essential if your doctor has advised you to avoid it. If you can tolerate casein, it's an effective protein for building muscle, and those desiring an edge in their training seek out food products with a heavy dose of it.
Casein and whey are the two primary protein types in milk. All cow's milk contains casein. Cream, half and half, yogurt and sour cream are other obvious sources of the protein. Ice cream, butter, cheese and pudding also contain it. Foods made with these products -- such as cream-based soups, sherbet, pudding and custard -- are also casein-rich. Dairy milk alternatives -- such as coconut, almond and soy milks -- do not contain casein.
Less Obvious Sources
Margarine, tuna, dairy-free cheese, non-dairy coffee creamer, semisweet chocolate, cereal bars, cheese-flavored chips and snack crackers, processed meats and ghee may have traces of casein. Baked goods are another food of which to be wary because many contain milk or buttermilk. These foods are of concern for those allergic to casein. If you want to use casein as a supplement to encourage muscle growth after workouts, these types of products that contain small amounts of casein should not be your focus.
Reading food labels helps you identify the presence of casein. The ingredients "lactic acid" and "artificial flavorings" mean a food could have casein in it. Avoid these products, or call the manufacturer to make sure they're safe if you have an allergy. Foods that list "caseinate" on the label definitely contain casein. Beware that dairy-free doesn't mean casein-free.
Protein Powders and Bars
The International Society of Sports Nutrition recommends that athletes who consume protein supplements opt for a combination of whey and casein proteins around the time of a workout because they are highly digestible, contain a complete array of amino acids and likely assist in muscle growth. Casein is a popular addition to protein powders and bars and is usually highlighted on the label. Whole food sources good for muscle growth supplementation of casein include cottage cheese and a glass of milk.