It would be the iris and the lens
Zinc - whole grains, ...
Protein - analogues, ...
vitamin D - sunlight
B12 - fortified soy milk, yeast, ...
Omega 3 - enriched eggs, ...
Calcium - greens, ...
Iron - dark leafy greens, ...
This is true. Severe allergic reaction can result in anaphalactic shock and death.
I think it would be kidneys because of the way the question is worded, kidneys are the only things you have 2 of that also is involved in the digestion of foods.