Proteins are essential for life; every cell in your body contains some protein. Even bodily fluids -- except urine and bile -- have protein. You need to eat protein so your body can repair itself and maintain healthy cells in your skin, muscle and organs. Both mushrooms and meat products contain protein, though the amounts and structure are different.
Mushrooms contain small amounts of protein, much less than meat. A half-cup of raw mushrooms has around 1 gram of protein. The amount of protein in meat varies by type. Lean meats have the most protein for the smallest number of calories. A serving of lean meat contains around 7 grams of protein and 45 calories. For example, 1 ounce of select or choice beef trimmed of fat and 1 ounce of fresh or frozen fish equals one serving. Three grams of luncheon meat and 1/2 ounce of beef jerky is also one serving.
Dietary protein is not one substance, but actually a combination of amino acid molecules. The term "complete protein" refers to a food that has all of the essential amino acids your body cannot make by itself. However, these foods do not have entire protein molecules, just the amino acids. Meats are always complete proteins. Mushrooms can still form a complete protein when combined with foods that make up the missing amino acids. For example, mix mushrooms with broccoli and corn to make a complete protein.
Knowing the content of protein is only useful if you know how much protein you need. According to the Physicians Committee for Responsible Medicine, the average person in the United States eats about twice the amount of protein he needs. The Recommended Dietary Allowance, or RDA, for most sedentary adults is 0.8 grams of protein per kilogram of weight. Multiply your weight in pounds by 0.36 to determine an estimate of your daily recommended protein intake. The PCRM states that this estimate is higher than most people need, but some people -- such as highly active people or women who are pregnant or breastfeeding -- may need more. Ask your doctor for an exact recommendation.
Meat's higher protein content often comes with more calories per serving. Around 3.5 cups of mushrooms has 7 grams of protein with only 56 calories. Medium-fat and high-fat meats have significantly more calories. A 1-ounce serving of medium-fat meat has 4 to 7 grams of protein and 75 calories. A 7-gram serving of high-fat protein has 100 calories. Most poultry is a medium-fat source; this includes fried chicken and ground turkey. Meatloaf and ground beef are also medium-fat foods. Two slices of pork bacon, three slices of turkey bacon and hot dogs are examples of high-fat foods.