Here is an basic but informative article mentioning many of the health benefits of olive leaf as a health supplement.

https://www.mindbodygreen.com/articles/olive-leaf-extract-benefits-and-side-effects
By Stephanie Eckelkamp

Excerpt: "The good news: Supplement manufacturers are able to produce something called olive leaf extract, which contains a stable, standardized form of oleuropein so you can reap the benefits (in concentrated form) without having to consume huge quantities of olive oil." ...(more)