I agree with that - when anxiety has a nutritional basis, it makes sense to target therapies to nutrition.
If we just use our thoughts to calm a nutritionally based anxiety, we might feel hopeless as it keeps coming back... and that would ADD to anxiety.
I certainly know about anxiety that comes on without any emotional trigger, nothing going on that I should or would be anxious about, it is "just there". I can't seem to get a handle on it when it comes on like that - I think the glucose idea fits really well with what I know about myself and my anxiety attacks.