Doctor's Best D-Ribose is a unique 5-carbon carbohydrate that is a fundamental building block of ATP (adenosine triphosphate), the source for all cellular energy. Ribose is the starting point and rate limiting compound in the synthesis of these fundamental cellular compounds and the availability of ribose determines the rate at which they can be made by our cells and tissues. Studies have shown that ribose supplementation can enhance cardiac energy levels and support cardiovascular metabolism. Further studies suggest that ribose plays a role in supporting muscle energy recovery after exercise. Exercise increases free radical production in muscle tissue. Ribose may strengthen and support the body’s crucial antioxidant defenses.