Canning is one of the safest ways to preserve foods. The vitamin levels in canned food remain stable during the shelf life. Nutrients are retained in canned foods because the can is completely air-tight and vacuum-sealed.
Canned poultry and fish, both high-protein foods, are comparable to their fresh- cooked counterparts in nutritional value. Protein is not lost during canning and some varieties of canned fish tend to have higher calcium levels.
Many canned fruits and vegetables are high in Vitamin A and also have comparable levels of vitamins to their fresh or frozen counterparts.
Most Vitamin C is retained after being canned and remains stable during the shelf life of the product. Canned asparagus, grapefruits and pineapple are good sources of Vitamin C.