For people with food specific allergies, there's another fairly specific way that people are able to eat healthier due to smart phones. It's actually quite life changing. Last year through blood tests and biopsy I was diagnosed with Celiac Disease. That basically means my immune system attacks my intestines if I eat anything with gluten in it. Even a microscopic amount of gluten is too much, so kitchen contamination is a big problem and if people don't understand it, I will probably get contaminated food.
There are 2 iPhone apps that I don't know how I could live without:
1. "Find Me Gluten Free" - Shows me restaurants that are gluten aware. This allows me to eat out without the fear of hidden gluten in my food. I'm sure there are similar apps for every common allergy, such as peanuts.
2. "Gluten Free Ingredients" - Has a catalog of ingredients and lists if they can contain gluten or not. When someone hands me a packaged food that I'm unfamiliar with, I can quickly verify that there is no gluten in the product.
For people like me, I just can't imagine living without my iPhone. If it were 10 years ago I would mostly be relegated to eating at home or bringing my own food with me when I went out. Now I can even travel without concern.
I think if someone can distill that formula, it could be a life changer - esp. if you can appeal to kids now in their formative years.
In the same vein, here is an iPhone app that extrapolates on the concept (ie: making nutrition fun):
*full disclosure: I know the developer but it's an amazing product nevertheless