Paul said, correctly , that all things are lawful, but all things are not expedient.
I don't eat pork. Nor do I eat shellfish. The reasoning has not changed in the thousands of years: hogs and pigs do not have sweat glands, and thus all the toxins build up in their bodies. And, like the shell fish (shrimp, oysters, lobsters etc) they are the garbage cans of the earth...they eat the garbage no other animal will eat. The shell fish eat the left overs of whatever the other fish leave and eliminate. Yuk.
A
lot of false information.
Pigs are omnivorous and their diet consists of mostly of grass, flowers, leaves, roots, and fallen fruits. Farm-raised ones eat very healthy: corn or soy meal enriched with vitamins and minerals. It is the latter kind you find in your local grocery or meat store.
Furthermore, pigs expel waste just like humans, through their excretory system, just like we do. Pig biology includes lungs, kidneys, bladder, and a full digestive tract. The fact that they don't sweat doesn't mean they don't expel toxins. Sweat isn't an excretion but a secretion for temperature control and hormones. That is why pigs roll in mud; because they are unable to use sweat to cool off.
All meat is dangerous is not cooked properly. You can just as easily get a parasitic infection or food poisoning from undercooked beef or poultry as you can from undercooked pork. So long as you prepare pork properly, it is quite nutritious.
Shellfish biology is able to successfully digest and convert whatever they eat into energy for survival. Furthermore, other animals eat them, and they are considered "clean," so truly, it is a Slippery Slope to say the scavengers are unclean but those who don't are not. Furthermore, I might add that fungi is considered kosher, and fungi live off the decaying remains of once-living things.
I quite enjoy a delicious pork chop - I season mine with sea salt, black pepper, garlic salt, basil, marjoram, oregano, thyme, and rosemary. Medium-high heat in a skillet with extra virgin olive oil. I also love an excellent crab and lobster bisque and I absolutely adore calamari. Also, a pizza is never complete without mushrooms!