YAY!!! Something I *think* I can sorta answer here!
Funny you should ask this because I just asked this very same question the other day on facebook. I did not really get the answer I was looking for, so I did a bit of my own research and came to my own conclusions on this question. 6 months ago when we started this board I knew nothing about any of this, but when dog food questions started popping up I started to find out we were not doing what was best for our dogs. In fact, you could probably find a thread here on this board, where we recommended Iams!
So the answer to your question is yes and no. Bulldogs are prone to allergies simply because they do not all have strong immune systems. So many bullies are the results of bad breedings/breeders, and new owners not being educated on what steps they can do to build a nice strong immune system.
Now lets look at the answer to this question: What causes allergies?
Allergies are particularly bad during spring and fall, when pollens and molds are high. But allergies aren't just about a runny nose and scratchy throat. In fact, allergies are caused by a REACTION IN YOUR IMMUNE SYSTEM.
This is why we always say "try changing the food". Making sure your bully is eating a good diet is the start to building a strong immune system. Grains and corn are not easily digested, so this is why a grain and corn free diet is better for bullies.
Salmon oil will help with a nice shiny coat and prevent flare ups with itching and hot spots, when once triggered can lower the immune system as well.
Supplements add additional vitamins and minerals that cannot be found in any dog food. We use NuVet (you can find NuVet on our sponsors page, please!) for a supplement but there are other good ones out there, this is just the one we choose to use.
Probiotics/digestive supplements- we give our bullies a scoop of plain yogurt or canned (real) pumpkin a few times a week.
Healthy snacks & treats- grain free snacks and fruits and veggies only
Now, I am not basing any of this on fact however. I am basing this upon experience.
Mandy has shown no signs of being allergic to anything. She can eat anything, and wants to eat everything!!!
Molly had never even itched herself in 2.5 years. She was so healthy, and yes- she was being fed Iams.
When Molly's puppies (Yuna & Tidus) were about 5-6 weeks old, we brought Mandy home. Well, Molly was not too keen on this idea. So she started itching. Then since we did not know why she was itching, so we would not let her near the pups. Within 3 days of Mandy's arrival Molly was red and itchy all over her whole entire body and her hair started to fall out!!! I freaked out and could not understand why she was having an allergy- and tried to pin point what it coudl have been- this is when the vet said, "Well, she just had puppies, her immune system is low". So we treated her with antibiotics, because she had already gotten a skin infection. In just 3 days! We also had to give her allergy medications and medicated baths every two days. I felt so guilty- because she looked so terrible, skinny, and much of her fur had fallen out in places. This combined with the spring pollens, Mandy's arrival- the puppies being taken from her- just caused her to FLARE UP.
After 3 weeks of meds, she did look better. But I was beginning to wonder, was she going to be another Sara? (Sara was my full blown allergy bullie) Well, on this board, we began talking about dog foods. So we started doing the dog food ratings. I decided since Molly was almost out of Iams

that it was time for us to switch her food. So without a list we went to Petsmart and bought a bag of Avoderm. Our vet also suggested we get Salmon Oil. Within 24 hours she stopped itching- and she was still in the transfer mode! Within 3 days her hair began to fill in. Within just a couple of weeks she gained back her weight and you would have never known she was so sick! Her coat and skin looked amazing. I did not realize that she was not supposed to shed like crazy, have yucky looking wrinkles, smell stinky, ect. I just thought these were a "bulldog" thing. Although she never showed signs of allergies before, she definately does not look like the healthy bulldog I have now! I wish I would have known this so long ago!
So can you prevent allergies? You can do what you can. Just like humans, bullies can be allergic to anything- so always be ready to do an allergy work up if it is necessary, and then maybe do the shots if the allergies are not anything within your control.
Our Sarah was allergic to every protien except for fish and rabbit. She did not show any signs of allergies until she was around a year, when I changed her puppy food to adult food. She was allergic to every grain- her list was 20 different foods. Then she was also allergic to tons of outdoor and indoor allergens as well. She was miserable. We got her the allergy work up and even went so far as to have her facial wrinkle rope removed. I cannot even explain how badly she smelled. We did the allergy shots, but we were traveling the USA, and in places that the allergy work up (which was for Arizona) did not even have listed. She became miserable again- and even worse than before. It was a challenge and I sure wish I would have had this forum back then!!!! We were feeding her Science Diet Rabbit

and were clueless. Luckily I had a great friend in Lindathedogsmaid who we sent her to, and I still to this day feel guilty for never figuring it out back then!!!! That kind of guilt never escapes me. Linda had always told me about dog foods and such, but I thought Iams was a good dog food. Boy was I ever wrong!
Okay, I also want to point out that this is the 2nd time I typed this. My internet went out the first time and I did not realize it until I hit the post reply button!!! (copy now just in case!!)