Oil pulling is a… Tradition in ayurvedic medicine involving swishing sesame or sunflower oil (also coconut oil more recently) in the mouth for 15-20 minutes, then spitting it out. There are no scientific studies to support or deny claims for improving diabetes or asthma but some studies find benefits for oral health.
Gimmick. Not good.
Holistic? Some swear by it. However, there is no scientific basis for it, so i, for one cannot recommend it.