Food has basically five nutrititional properties:
Protein
Carbohydrates
Fat
Vitamins
Minerals
Proteins would help people grow stronger and heal physical wounds faster.
Carbohydrates would let them recover from tiredness faster.
Fat would protect them from hunger and bad weather.
Vitamins would protect them from illness.
Minerals let them move faster and protect them from hot weather.
In RL people would die from lack of one of those (besides fat, maybe), but in Cantr it shouldn't be so extreme. Yet it would be a good idea to carry fresh fruit and vegetables for long travels across the sea, and to trade food with other locations. This would replace the healing food for just "good kinds of food you should eat when you are ill/wounded".
There could be still instant healing herbs and medicines.
