Do gelatin and glycerin come from pork?

Answer 1

Gelatin is an animal product. It is a protein which comes from the bones and skin of the animal; in the case of ungulates such as cattle and sheep, the hooves can also be used to extract gelatin. Gelatin is usually extracted by boiling. Most commercial gelatin in the US is a byproduct of pork processing and does indeed come from pork. Gelatin derived from other animals is available, though not as widely as that from pork. For example, fish gelatin is used by one Kosher candy company to produce marshmallows. (Post hoc 11/30/2010: Since posting this answer, I have discovered that Kosher gelatin derived from beef is available as a consumer ingredient, marketed under the brand name Kolatin, and bought a few packages of the stuff for my own use at home.)

Gelatin has long been regarded as a beneficial nutrient to consume for length and health of nails. However, since the chemical structure of gelatin contains no essential amino acids, its benefit is dubious at best.

As for glycerin, because it is a carbohydrate (in other words, not a protein) it can come from either animal or vegetable sources. Vegetable-derived glycerin should be labeled as such. Without such a label, one cannot assume that the product is vegetable-derived.