Bacon and Bats: Linked to Disease?
A main theme discussed in Parshas Shemini is what are considered Ma’achalos Asuros (forbidden foods). The Torah forbids these types of foods, and the foods that are permitted must be properly prepared. The Torah uses the language “that you[r soul] will be contaminated through them.” However, not only does it affect one’s soul, but the Ramban brings down medical reasons to avoid consuming Ma’achalos Asuros.
One example the Ramban brings down (11:9) is that it is healthier to eat fish with kosher signs than fish without these signs (fins and scales). The reason is that fish that have fins and scales reside towards the top of the ocean, therefore the warmth and nutrients ward off unhealthy moisture to the consumer. However, fish that live in deeper waters don’t have this advantage, and they have more ‘moisture’ and, therefore, are more unhealthy to consume. The Ramban also mentions that one of the reasons for the simanim of kosher animals (split hooves and chew their cud) is because they are herbivores. The Ramban notes that he saw in records of medical experiments that a child who suckles from a pig will become a leper, which indicates the harmful natural properties of non-Kosher animals.
There are other Rishonim who follow this approach as well. Rashbam quotes a gemara (Shabbos 86b) that those who consume Shekatzim u’Remasim (bugs and vermin) have a higher body heat, which can increase the chance for bodily harm. The Ibn Ezra in Shemos (22:30) states that the reason a treifa (a mortally ill animal that will die within 12 months) is given to a dog is because it is unfit for human consumption because of damaging spiritual and physical properties. (There are many more Rishonim who offer medical reasons for the prohibition of Ma’achalos Asuros. See Rikanti and Seforno Parshas Shmini, and the Sefer haChinuch 154, Rabbenu Bachya in Shemos 23:19).
However, these are not the main reasons behind the prohibition of Ma’achalos Asuros. Even if scientific research confirmed these not to be true, it would not remove the prohibition on consuming these items. Like all commandments in the Torah, a mitzvah contains many mystical and hidden reasons, regardless if one reason or not, has a medical basis not to be true.
Adapted from medicalhalacha.org