Why is ham better than turkey?

Your question is vague, but I assume you mean "why is turkey healthier than ham."?

Ham is smoked, and smoked foods (bacon, ham, weiners, smoked sausage, etc) all contain nitrites from the smoke. These substances are carcinogenic: in other Words, they can cause cancer when eaten too often because they cause irritation to cells. Liquid smoke and smoke flavour typically include these compounds as well. While there is much debate on how much is too much when it comes to smoked foods, they should be consumed in moderation. Ham is also typically very high in salt and sometimes, in sugar. Turkey is typically served fresh (not smoked or salt cured) so it's a source of meat protien without harmful additives.

That said, turkey bacon and weiners are no more healthy than ones made with pork because they typically have the same nitrites and salt content anyway. They may, however, have less fat. Read the package to be sure. But don't assume that eating processed meats made with beef, chicken, or turkey is any better for you.

In general, most diet experts recommend that you limit the intake of cured, smoked and salted meats (and processed foods in general) and try to eat more fresh and unprocessed foods.