Read Lev 11 at Bible Gateway.
In Torah, God forbids His people from eating certain classes of animals as food, calling them unclean. Some of the health benefits that accompany eating the foods which God has declared clean in Lev 11, while avoiding the foods which God has declared unclean in Lev 11, are:
Animals that divide the hoof and chew the cud. These are primarily grass- eating livestock, such as cattle, deer, antelope, elk, sheep, goats. It has been found that the meat of this class of livestock which has been grass fed (not grain fed) is high in essential fatty acids, a class of fatty acid which is essential for the physical health and function of the human body, but which the body cannot make itself and must be supplied through diet. Disease conditions associated with an essential fatty acid deficiency are numerous. All manner of emotional and mental disorders, such as depression, bipolar, addictions, even schizophrenia have been shown to either present or worsen with an EFA deficiency (new research shows that EFAs might also affect Alzheimer’s.) Pregnancy, birth, and lactation complications increase with an EFA deficiency. Obesity, diabetes, cancer, and heart disease increase with an EFA deficiency. Intestinal imbalances resulting in food allergies or IBS or other intestinal complications present or worsen with an EFA deficiency. Hormonal imbalance conditions present or worsen with an EFA deficiency. Skin and hair conditions such as excema present or worsen with an EFA deficiency. Research is ongoing on EFAs and the human body, but the list of systems a deficiency impacts is enormous and growing.
Pig is unclean. This animal, at least, is not a grass eater but an omnivore, a trash eater. It does not contain sweat glands in the skin that the livestock mentioned above do, and as a result it retains a much higher percentage of toxins in its body and internal tissue. It is also prone to many different types of parasites, some of which survive in the meat at very high temperatures. Its habits, moreover, are dirty. (Eating Pork can be Hazardous to your Health.)
Fish without fins and scales are unclean. The catfish is an example. The catfish also happens to thrive in dirty, sluggish water where it scavenges the bottom for food. Sharks do not have scales. Shark will eat a man if available. Shellfish do not have fins or scales. They are the garbage scows of the ocean. Are we beginning to see a pattern, LOL. Shellfish moreover are covered with a strain of cholera bacteria which helps break down the hard substance of the shell. Cholera can be a deadly disease for humans.
The unclean birds are all carrion eaters or birds of prey, the clean birds are vegetation or seed eaters. And on and on.
The purpose of Torah obedience is NOT and never has been salvation, or life for the spiritual man. Moses specifically taught in Torah that its purpose is not righteousness unto salvation. Its purpose has always been, to bless us with happiness, health, wealth, and any other thing which is needful for life for the physical man. God was looking to promote our health in making the division of clean and unclean food, and I trust that as Creator of all, He is smarter than I am! He knows what He is talking about and what is good for me.