We established a zinc-app based on a biochemical validated questionnaire, to estimate the zinc intake of persons. In fact the app gave better results than serum zinc measurements. Our geriatric department already uses the app as clinical routine. The respective publications are mentioned in the app. The app is now online www.zink-app.de and can be used free of charge. Please find the QR code attached. The app is available in German and English (just click on the flag).
I hope this tool will be helpful for your research.
There are still some problems with uploading the Android version of the app for smartphones, that you will be independent of internet access, but you will receive the information as soon as possible.