Adenosine triphosphate (ATP) is the main energy molecule inside cells. Oral ATP supplements, however, break down quickly in the digestive tract and reach the bloodstream in very small amounts. Because absorption is poor, there is little clinical evidence that these pills improve energy or athletic performance.
Some people take ATP hoping to support energy metabolism, but any effect likely comes from breakdown products like adenine nucleotides, and even that remains unproven. A few early studies hinted at minor effects on blood vessel function, but medical groups such as the NIH do not back this supplement for any use. Pregnant or breastfeeding individuals should avoid it, since safety data are lacking.