On what Muslims may not eat, there are clear instructions:
''He hath only forbidden you dead meat and blood and flesh of swine, and that on which any other name hath been invoked besides that of Allah. But if one is forced by necessity, without wilful disobedience, nor transgressing due limits, then he is guiltless. For Allah is Oft-Forgiving, Most Merciful.'' (2: 173)
Vis-à-vis forbidden dead meat, it is related in Fiqh (Religious Law) anything that dies of itself and is not expressly killed for food with Takbir duly pronounced on it. There are exceptions, e.g., fish and locusts are lawful, though they have not been made halal with Takbir. But even fish or locusts as carrion would be obviously ruled out. Dead meat or blood as an article of food would obviously cause disgust to any refined person, besides it is unhealthy.
What is forbidden has a scientific basis, as substantiated by various studies. That swine is fed on offal is itself a case against consumption of pork, but even it were cleanly fed, scientific evidence against consumption of pork is overwhelming. The meat of swine (pork) has very high fat content, hence has harmful cardiovascular effects. Swine flesh has the highest fat content of all the meat products, used for human consumption. Apart from high fat content, it is more liable to cause disease than other kinds of meat; e.g., trichinosis—characterized by hair like worms in muscular tissues.
Excessive fat content has other health hazards. It leads to excessive consumption of Vitamin E. Vitamin E is quickly consumed in those he eat pork, hence a latent Vitamin E deficiency emerges. Vitamin E influences sexual glands, hence deficiency may affect sexuality. Vitamin E deficiency leads gradually to Vitamin A deficiency, which in turn leads to skin related and eye related illnesses.