Lycopene is the fat-soluble pigment that gives tomatoes, watermelon, pink grapefruit, and other foods their red color. Bioavailability of lycopene is enhanced in the presence of lipids and thermal processing. Lycopene accounts for about 50% of the carotenoids found in human serum and is among the major carotenoids present in human milk. The antioxidant activity of lycopene and its use in cancer prevention and cardiovascular disease have been widely documented. The scientific literature documents some adverse reactions, such as diarrhea, dyspepsia, gas, nausea, and vomiting. One trial documented a cancer-related hemorrhage in a patient taking lycopene, although causality is unclear. Lycopene interacts with some cancer chemotherapy agents, as well as with ciprofloxacin and olestra.