Dietary supplement
According to US & Canadian Dietary Reference Intake guidelines, the protein Recommended Dietary Allowance (RDA) for adults is based on 0.8 grams protein per kilogram body weight. The recommendation is for sedentary and lightly active people. Scientific reviews can conclude that a high protein diet, when combined with exercise, will increase muscle mass and strength, or conclude the opposite. The International Olympic Committee recommends protein intake targets for both strength and endurance athletes at about 1.2-1.8 g/kg body mass per day. One review proposed a maximum daily protein intake of approximately 25% of energy requirements, i.e., approximately 2.0 to 2.5 g/kg.
Beef
Beef is a source of complete protein and it is a rich source (20% or more of the Daily Value, DV) of Niacin, Vitamin B12, iron and zinc. Red meat is the most significant dietary source of carnitine and, like any other meat (pork, fish, veal, lamb etc.), is a source of creatine. Creatine is converted to creatinine during cooking.Excessive consumption of red processed meat is known to increase the risk of bowel cancer and some other cancers.The Harvard School of Public Health recommends consumers eat red meat sparingly as it has high levels of undesirable saturated fat. This recommendation is not without controversy, though. Another study from The Harvard School of Public Health appearing in Circulation (journal) found "Consumption of processed meats, but not red meats, is associated with higher incidence of coronary heart disease and diabetes mellitus."