I've been thinking about the need for such a database as well and it's great to see such a project launching in Switzerland. What I would find particularly useful (and existing databases like migipedia.ch unsurprisingly don't offer) is the tracking of any changes in the recipes of the products. I believe it's a well known secret that lots of retailers keep adjusting the recipes - usually for cost saving purposes.
I was telling my wife last night about the Migros (a swiss retailer) smartphone application that I've started using recently (allows you to access list of new products, special prices, reduction code, list of recent purchase etc). Crawling the application I found it gave me a list of the most frequently purchased items per category (dairy product, vegetables, fruits, pastry, etc.). I told her how interesting it would be if I could just, from this list, select what I eat and when and I would get a nutrition report out of it.
The application already has nutrition data and list of ingredients for most item so it's hopefully not far from happening ! Problem is I probably won't be given access to it...
Years ago I applied for API access with the intent of making an app for diet tracking, but was denied. (And from what I've heard, queries would have been prohibitively expensive.)
The calorie/nutrition application I use is able to do this, CRON-O-METER. It has many existing food products, and even allows you to add your own recipes or custom foods and generates a nutrition label for them. It also generates many aggregate trackers. I use it to keep track of my food and exercise, which works well for me as I follow a diet of--each whatever I want as long as it fits in my calories and hits my nutrient quotas, which means I no longer feel bad if I want some junk food as long as it's those bounds. The only disadvantage is you can't view historical aggregated data, only "raw" data without paying for a subscription, but I've gotten by without a subscription for a good while.
You're talking about manually entering what food you eat (I believe).
GP is talking about the fact that the supermarket already knows every item you buy and keeps it in their big database. This could easily be used to track nutrition with little to no user input.
