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Do not build this. The database is decades of work and it is the entire product.

Micronutrients from laboratory sources, verified rather than crowd-submitted, is the difference between a food tracker that tells you something and one that tells you what a stranger typed. You cannot recreate it, and a tracker built on user submissions will confidently report a vitamin figure that is wrong.

WHAT TO DO INSTEAD
- Keep it if you track micronutrients. That is what it is for and nothing else does it as carefully
- If you only count calories and protein, that is a much smaller problem and the free tiers of several tools cover it

WHAT YOU CAN BUILD, IF YOU WANT THE DATA ON YOUR OWN MACHINE

Use an open food composition database as the source — several national ones are published freely with laboratory-derived values — and build the logging around it:

STACK
- A PWA that works offline, SQLite on device, an optional sync server storing ciphertext

WHAT TO IMPLEMENT
- Import the open database once, with its version recorded, so a figure can always be traced to its source and its edition
- Log a food in three seconds: search, pick a portion, done. If it takes longer it will not happen five times a day
- Recent and frequent foods first, and a saved meal that logs six items at once. That is where the speed comes from
- Recipes: ingredients in, nutrition per serving computed, stored as a food
- Barcode scanning against an open product database, with the honest note that open product data is patchier than a commercial one and a missing barcode means typing it in
- Targets per nutrient with a source cited, and never a number presented as medical advice
- Write to the platform's health store so it appears alongside everything else, and read back what other applications recorded

THE HONEST WARNING
Nutrition figures vary by cultivar, soil, cooking method and brand. Any tracker's numbers are an estimate with a wide margin, and a tool that displays them to two decimal places is lying about its own precision. Show ranges or round generously.

THE ONE-LINE VERSION
The verified database is the product. Build the logging on top of an open one, and be honest about the error bars.