Metaphasic radiation
Metaphasic radiation is a technobabble fountain of youth in Star Trek: Insurrection. It has allowed the Ba'ku to live to be hundreds of years old and apparently has completely eliminated disease. The Federation wants to harvest it to assist its general population and give themselves an advantage in their various wars and conflicts. They expect human lifespan will double with the harvested radiation. We are told the Son'a want this resource to save their dying race but it is more for the sake of revenge. Members of the Enterprise crew exposed to it began noticing the effects within days. Their appearance and behavior started reverting to more youthful stages. The most noticeable changes were Geordi Laforge growing new eyes and one of the crewmembers losing a baby as she reverted to a prior state of pregnancy.