To be honest, the reason why Jews and Muslims don't eat pork is because God forbids Muslims and Jews from eating pork!
The Quran doesn't give a reason, other than a reference to pigs being dirty (contrast that with alcohol where God says there is some good in it, but the bad outweighs the good).
Therefore the justifications on health grounds given by some are just people trying to understand the reasons why pork may be forbidden.
From what I've read (and from memory):
1. Pork has high fat content
2. Pork is more prone to parasites/bacteria - that is why steak tartare (raw beef or lamb) is ok, but pork has to be thoroughly cooked (even today where the argument is that pigs are more hygenically raised than in the past)
3. It is a white meat and similar to human flesh (cannibals in the pacific refer to human meat as 'long pig', people say that burnt humans - at fires, explosions etc - smell like bacon/pork (sorry, I know it's gross).
4. Pigs are anatomically similar to humans - and one of the issues of xenotransplants is that the porcine retro-viruses etc may easily mutate and cause harm in humans. Pigs are used to produce hormones that can be used by humans (insulin, for example IIRC).
3 and 4 are my personal observations - and I use as additional reasons why it may not be advisable to eat pork on health grounds (I mean if the concerns about pig viruses are an issue in transplants, then shouldn't you treat pig flesh the same way you'd treat the bodily fluids of a suspected aids victim?)
Just my 2 cents - but there's quite a lot of material out there on the subject. (However, I'm not sure that's a reason why doctors/dieticians would say pork is bad for your immune system.)
Good luck with the diet!
Edit: Did a quick Google - found this article:
http://knol.google.com/k/human-pathogen ... s-of-pork#Cheers,
Shafique