How much does canning reduce nutritive value?

[Guest guest]

How much does canning lower a food's nutritive value? Traditional methods of

preserving foods such as cold storage, lactic fermentation, storing in vinegar,

oil, sugar and alcohol are superior food preserving methods according to many

because they not only maintain nutritive value better than freezing or canning

but some of these traditional methods supposedly also enhance nutritive value.

How much better are traditional food preserving methods than freezing and

canning, and does canning reduce nutritive value significantly for food that are

going to be cooked anyway?