As far as concord grapes go, the seeds are in fact edible and actually highly nutritious. These seeds contain antioxidants which are important for your body to have because they help to fight off health problems like heart disease and even cancer. Although these seeds are completely edible and nutritious, they can be hard to chew because of their texture.

It is not recommended that you eat grape seeds on a regular basis because they are hard on the teeth, though it is okay to eat them once in a while, especially because of the antioxidants and other things which they can offer you.