Not always. In some cases, the canning process locks in nutrients and in other cases it can enhance the availability of nutrients.
- Canned blueberries contain more of the powerful antioxidant, anthocyanin, than either fresh or frozen.
- Canned salmon is richer in heart-healthy omega-3 fats and calcium than fresh.
- Canning releases health-promoting antioxidants. One half cup of canned tomatoes contains 11.8 milligrams of lycopene compared to 3.7 milligrams in a medium fresh tomato.
- The heat treatment in canning carrots, spinach and pumpkin enhances the availability of carotene which is converted to vitamin A in the body. One-half cup of canned pumpkin has three times more beta carotene then fresh cooked pumpkin.
- The amount of available lutein in corn, an antioxidant that protects your eyes, is enhanced by the canning process.
- The fiber found in fruits and vegetables is unchanged by the canning process.