“I am the Lord who has brought you up from the land of Egypt to be your God. So you shall be holy, because I am holy” Leviticus 11:45
Dayan Isidor Grunfeld, in his book Dietary Laws, explained that the three strongest natural instincts in man are the impulses for food, sex and the pursuit of material wealth. The strongest of these three impulses is food; it is no coincidence that the first prohibition given to Adam and Eve was not to eat from the Tree of Knowledge.
I have often heard people come up with the most unlikely of reasons for kashrut; the most absurd being that “there were no fridges in the wilderness, therefore the people had to salt the meat”. There is no indication whatsoever as to this being the reason; moreover, it does not address the whole gamut of kashrut, such as shechitah, the ban on eating bugs and eating only kosher fish.
Kashrut remains, like most of the Torah, a statute – a mitzvah for which the true reason eludes us. Nevertheless, there are some hints as to its purpose. At the end of the passage on kashrut we are taught that “I am the Lord, your God who brought you up from Egypt.” Rashi, quoting the Talmud, explains that the phrase “brought you up” implies that we are elevated through kashrut. We also learn from it restraint and compassion.
The impact of non-kosher food on the soul is a bit like the impact of cholesterol on the heart. Rambam stated that a Jew who eats treif will find that his cognitive ability to reason properly will be damaged. Kosher food plays a fundamental part in the physiological and spiritual make-up of a Jew.
When times are economically tough, there is greater temptation to discard kashrut in view of cheaper food elsewhere. Just as tzedakah must be maintained during economic hardship, so too must kashrut. As Ben Hei Hei said in Ethics of the Fathers (5.27), “According to the difficulty in a mitzvah, so the reward is commensurate.”