The use of guanidinoacetic acid and/or salts thereof in combination with choline and/or betaine to produce an agent for improving brain function, bone growth and the mineralization of bones, for improving cartilage growth, for alleviating aging processes, for strengthening the immune system, as an antioxidative and neuroprotective agent, for lowering the cholesterol and triglyceride value, for preventing inflammatory processes and for lowering the blood sugar level in humans and vertebrates is described.In this connection it has surprisingly turned out that the new agents have a considerably higher bioavailability and are thus better taken up into the cells than was previously known when using creatine.
