What are some health benefits for a kosher diet? The Rambam and ibn Ezra said that all the mitzvahs has to have a rational explanation for them. Ibn Ezra said that if a single commandment went against reason (intelligence) then we should not observe it. That is to say, that he found a real reason for each and every command. A kosher diet should have health benefits like a bris. What does our sages’ have to say regarding this.
Rambam does indeed explain the health benefits of the various kosher laws in Guide for the Perplexed 3:48:
I maintain that the food which is forbidden by the Law is unwholesome. There is nothing among the forbidden kinds of food whose injurious character is doubted, except pork (Lev. xi. 7), and fat (ibid. vii. 23). But also in these cases the doubt is not justified. For pork contains more moisture than necessary [for human food], and too much of superfluous matter. The principal reason why the Law forbids swine's flesh is to be found in the circumstance that its habits and its food are very dirty and loathsome. It has already been pointed out how emphatically the Law enjoins the removal of the sight of loathsome objects, even in the field and in the camp; how much more objectionable is such a sight in towns. But if it were allowed to eat swine's flesh, the streets and houses would be more dirty than any cesspool, as may be seen at present in the country of the Franks. A saying of our Sages declares: "The mouth of a swine is as dirty as dung itself" (B. T. Ber. 25a).
The fat of the intestines makes us full, interrupts our digestion, and produces cold and thick blood; it is more fit for fuel [than for human food].
Blood (Lev. xvii. 12), and nebelah, i.e., the flesh of an animal that died of itself (Deut. xiv. 21), are indigestible, and injurious as food; Trefah, an animal in a diseased state (Exod. xxii. 30), is on the way of becoming a nebelah.
The characteristics given in the Law (Lev. xi., and Deut. xiv.) of the permitted animals, viz., chewing the cud and divided hoofs for cattle, and fins and scales for fish, are in themselves neither the cause of the permission when they are present, nor of the prohibition when they are absent; but merely signs by which the recommended species of animals can be discerned from those that are forbidden.
The reason why the sinew that shrank is prohibited is stated in the Law (Gen. xxxii. 33).
It is prohibited to cut off a limb of a living animal and eat it, because such act would produce cruelty, and develop it: besides, the heathen kings used to do it: it was also a kind of idolatrous worship to cut off a certain limb of a living animal and to eat it.
Meat boiled in milk is undoubtedly gross food, and makes overfull; but I think that most probably it is also prohibited because it is somehow connected with idolatry, forming perhaps part of the service, or being used on some festival of the heathen. I find a support for this view in the circumstance that the Law mentions the prohibition twice after the commandment given concerning the festivals "Three times in the year all thy males shall appear before the Lord God" (Exod. xxiii. 17, and xxxiv. 73), as if to say, "When you come before me on your festivals, do not seethe your food in the manner as the heathen used to do." This I consider as the best reason for the prohibition: but as far as I have seen the books on Sabean rites, nothing is mentioned of this custom.
The commandment concerning the killing of animals is necessary, because the natural food of man consists of vegetables and of the flesh of animals: the best meat is that of animals permitted to be used as food. No doctor has any doubts about this. Since, therefore, the desire of procuring good food necessitates the slaying of animals, the Law enjoins that the death of the animal should be the easiest. It is not allowed to torment the animal by cutting the throat in a clumsy manner, by poleaxing, or by cutting off a limb whilst the animal is alive.