If you have food allergies, you may not want to call attention to yourself by mentioning them at work. Although allergy awareness and precautions are spreading in the school systems, you don't want to stick out like a sore thumb or be considered "weak" at work and might want to keep your own "private" issues under wraps. But hiding your food allergies from your colleagues can turn out to be very dangerous, even if you think you have your allergies under control.
People who don't have experience with food allergies may think they just cause sneezing or a runny nose. You'll have to tell them, in a nonconfrontational way, exactly what your allergy entails. Your boss and colleagues need to know about your allergies so they won't inadvertently expose you to an allergen, and in case you should have a reaction and need their assistance. Even if you haven't had any serious allergy symptoms in the past, it is always possible for your allergies to get worse over time. If you have difficulty breathing or go into anaphylactic shock, which is life-threatening, they'll need to know why this is happening and what you're allergic to so they can tell the paramedics if the need arises. If you have an epinephrine auto-injector to combat severe reactions, at least one person in your office should know where you keep it and how to use it.
The ADA (the Americans with Disabilities Act) gives employees with disabilities, which include allergies, the right to a safe and healthy work environment and bars employers, employees and businesses from discriminating against you based on your physical needs. If you are treated unfairly at work because of your allergies and your company refuses to make the changes necessary for you to work safely, you can file a complaint with the United States Attorney General or file a private lawsuit for a court to require your company to make the necessary changes and pay your legal fees.