Kashruth, similar to observance of all other mitzvot, affects ones character. Mitzvot are an effort on the part of G-d to make each Jew a better person. One who lives by Torah/Jewish law is learning to overcome his desires in favor of G-ds desires. Not, What do I want?, but What does G-d want?
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Some think that kosher food is more healthy, and that hygiene underlies all the kosher laws. While kashruth may result in food that is cleaner and healthier, we do not serve G-d because of the benefits we may derive from it. (While G-d does not make demands of us that are harmful to us, the reason we perform mitzvot is because this is a means of coming close to G-d and expressing our allegiance and subservience to Him. G-d makes no promises that kosher food makes us healthier, or more handsome, or prevents wrinkles, or keeps our teeth white, or restores our hair. The delight in serving G-d, regardless of whether or not it is convenient or comfortable, is the ideal service of G-d.