| occurring hormone | 1.45 | Androstenedione supplements are made of a naturally occurring steroid hormone. | ||
| occurring substance | 1.25 | Creatine is a naturally occurring substance in food. | ||
| occurring bacterium | 0.79 | Naturally occurring bacteria essentially eat the trash. | ||
| occurring protein | 0.53 | TPA is a naturally occurring protein that dissolves clots. | ||
| occurring chemical | 0.33 | These changes are caused by fluctuating levels of serotonin, a naturally occurring chemical in the body. | ||
| occurring gas | 0.33 | Radon is a naturally occurring radioactive gas that escapes from underground rocks and soils. | ||
| occurring compound | 0.26 | OH is a naturally occurring compound that helps clean many pollutants in the lower atmosphere. | ||
| occurring metal | 0.26 | Mercury, a naturally occurring metal, is also released by burning trash or coal. |