Describe the process of hydrogenation. why is this a concern in regard to nutrition?

To hydrogenate something is simply to add hydrogen to it. To start the process, you need something that has places where hydrogen can stick. Adding hydrogen involves ripping one of those bonds apart, so instead of one carbon atom being double bonded to the next carbon atom, the carbon atom has a single bond with the next carbon atom, and a single bond with a hydrogen atom. The bad side is it produces the "bad fats" like trans fat.