Kosher foods have been enjoyed by Jewish people for a long, long time. They are becoming increasingly more popular with non-Jewish people as well.
Kosher foods are regarded in many circles as being healthier than non-kosher foods. Some people believe that the standards for food preparation and food safety are higher and followed more scrupulously than elsewhere.
Some Muslims and Seventh Day Adventists, for instance, are more inclined to buy kosher foods with the knowledge that there is no chance that the kosher foods they buy will contain any traces of the foods from which they abstain.
"In general, kosher food has to be carefully watched throughout its processing and preparation. Grains, packaged vegetables, fruits and similar products are thoroughly inspected for any trace of non-kosher substances like insects. Because kosher laws prohibit the mixing of meat and dairy, all kosher dairy products are processed separately from any meat product. No shellfish is allowed, and all fish, like anything that is kosher, must be processed with utensils that have not been in contact with anything non-kosher."
http://well.blogs.nytimes.com