I read some where online that blueberries can be used to enhance black hair.  How am I supposed to use them?  How many?  For how long?  I couldn't find this information but I could just have poor searching skills.  My google shows Danish results first before anything else so it could just be many pages away.

What else can one find in the kitchen to temporarily enhance black hair?  I consider my hair soft black, off black+darkest brown and I'd prefer an overall natural off-black look rather than an actual blue-black look because that can make my complexion appear jaundiced.  It's the realization of that effect that made me stop going to the hairdresser for my annual blue-black overall dye three years ago.