The faq states that "nutrition unrelated to exercise, such as food safety, nutritional needs for children, etc." is off-topic. If you do write your question about nutrition such that it is related to exercise, then it would be on-topic.
At the current moment, there isn't any place where you can ask general nutrition questions. Historically, the site was getting questions that fell more along the lines of "general health and wellness" without necessarily relating to (physical) fitness. The problem with those questions was that people were, in a way, asking for validation of their choices. We also have the problem of not having a good base (if any) of nutrition experts who could answer those questions.
The discussion of the site's scope has come up numerous times in the past. As a result, the consensus was to focus the site on physical fitness and have nutrition be a secondary component of that.