Infants and children are particularly vulnerable.  Here to help us better understand these allergies and what we could do to control them, are two specialists in the field.  Dr. Morris Nejat is the director of the Division of Pediatric Allergy and Clinical Immunology at Bellevue Hospital Center.  He is also a clinical professor of pediatrics at NYU Medical Center.  Dr. Nejat, thanks for being here.

We also have Dr. Heidi Zafra, who is the head of Pediatric Allergy at St. Christopher's Hospital for Children in Philadelphia.  She is an assistant professor of pediatrics at the MCP Honneman School of Medicine, as well.  Dr. Zafra, let's begin with you.  Children and infants have the highest incidence of food allergies.  What are we talking about?  How many kids, and what percentages?

HEIDI ZAFRA, MD:  About 10-20% of children have food allergies, and often they are during infancy.  Often it starts when you introduce a lot of these foods early on in life.  That's why sometimes it's good to wait until the infant is older before you start introducing different kinds of food.  They may manifest as, just plain and simple rashes or eczema, or even wheezing, vomiting, diarrhea, with children with severe allergies.

PAUL MONIZ:  Do you find that children who are breast-fed fare better than children who receive formula?

HEIDI ZAFRA, MD:  Breast-feeding is really recommended for children, because they receive immunoglobulin from the breast milk.  That is protective, and helps the child.  It prevents a lot of food allergies.

PAUL MONIZ:  So it can be helpful?

HEIDI ZAFRA, MD:  It can be helpful, yes.

PAUL MONIZ:  What can parents do to prevent these allergies?

HEIDI ZAFRA, MD:  Basically, not to introduce different kinds of foods early on in life.  Start, let's say, with bland foods such rice and the cereals, barley.  Wait until they're about a year before you give cow's milk and egg and more exotic food.  Depending on the severity of their symptoms, sometimes children may need to avoid certain foods for six months to a year before you reintroduce the food, if they have severe allergies like lip-swelling, wheezing, generalized rashes or vomiting and diarrhea, just so you prevent a life-threatening situation.

PAUL MONIZ:  Dr. Nejat, let's bring you into this.  Can children outgrow their allergies over time?

MORRIS NEJAT, MD:  Oftentimes children do outgrow food allergies.  Usually if a child has a reaction to a certain food, and after we've documented it with skin testing, to see whether or not they truly are allergic to this food, we have the parent remove it from the child's diet until about two or three years of life.  Then we'll re-skin test them, and then possibly reintroduce the food at that point.

PAUL MONIZ:  You talked about some of the symptoms involving children -- the rashes, the wheezing, the swollen lips.  When adults are allergic to foods, how do they manifest?

MORRIS NEJAT, MD:  Usually with hives.  They could have swollen lips, they can have wheezing, throat can close up.

PAUL MONIZ:  Some of the same symptoms, really.

MORRIS NEJAT, MD:  Sure.  Children tend to have more eczema as a sign of food allergies.

PAUL MONIZ:  What is that?

MORRIS NEJAT, MD:  Eczema is a dry, itchy rash of the skin that can be anywhere, but usually it's in the arms or the legs.  Once you stop the offending food, it tends to go away over the course of a few days.

PAUL MONIZ:  So that's one of the telltale signs.  How much does genetics play a role in people's food allergies?

HEIDI ZAFRA, MD:  Allergic diseases, actually, there is a genetic predisposition.  If you have parents with any form of allergic disease, whether it's hay fever symptoms or asthma or food allergies, your child may have the tendency also to become allergic.  The earliest sign of allergic disease is the eczema, the dry, itchy skin that feels a little bit like sandpaper.

Oftentimes, as the eczema gets better, which it does over years, that's when all the other symptoms start to appear, your hay fever symptoms or your asthma.  But there is a very, very strong genetic predisposition.

PAUL MONIZ:  What are the most common food allergies in the United States, Dr. Nejat?

MORRIS NEJAT, MD:  In the United States, because of our diet, we have different food allergies than, say, Japan does.  The big food allergies here are milk, egg white, soy, peanuts, wheat, fish, and shellfish.  That's a fairly broad category.

HEIDI ZAFRA, MD:  Oftentimes a person's allergic to only one or two of the seven-eight common foods.  A person will only be severely reactive to a few of the foods, not all seven of them.

PAUL MONIZ:  You mentioned Japan.  What are the most common food allergies there?

MORRIS NEJAT, MD:  The Japanese have a diet high in fish and soy, so those are the two most common food allergies there, whereas here, the most common food allergies are peanuts, milk, and soy.

PAUL MONIZ:  It's interesting, though, because people are allergic to the very things that the society that they live in eats a lot of.

MORRIS NEJAT, MD:  Or that they particularly eat.  It's random; it's probability.  It's the same thing with environmental allergies.  If you live in New York, you're more likely to be allergic to dust mites, whereas if you live in New Mexico, which is a very arid environment, with low levels of dust mites, you're more likely to be allergic to the cat.

HEIDI ZAFRA, MD:  Out of all these food allergies, only peanuts and shellfish are not outgrown.  So if you find a child who's allergic to several foods, the milk, the egg, the peanut and the shellfish, you have to tell the mother that, probably, all his life he will have a problem with the peanuts and the shellfish, and he might outgrow all the other foods.

PAUL MONIZ:  Now eating peanuts can be deadly for some people who are highly allergic.  What happens in these patients as they have a severe reaction?

HEIDI ZAFRA, MD:  I oftentimes tell my parents to watch out for anything from the neck up.  The throat closing, a cough that starts up that's very, very tight, lip swelling, and tongue swelling.  These are signs that the airway is involved.  Or if there is wheezing.  If the child has asthma and the child is wheezing, then the parent should have an epi-pen, a pen with adrenalin, and should use the adrenalin and bring the child to the emergency room.

PAUL MONIZ:  Should children of any responsible age carry this epi-pen around with them?   What exactly is it, specifically?

MORRIS NEJAT, MD:  An epi-pen is a pre-filled device, which is a load of one dose of adrenalin or epinephrine.  What a child or anybody would do is, they would take the cap off, stick it against the leg through your clothes, and hold it there for ten seconds, so that the needle will come out, inject the dose.  You hold it there for ten seconds to make sure the whole dose is injected into the body.

It gives the patient about 15 minutes to get to the emergency room.  Using the epi-pen does not mean the allergic reaction is over.  It just buys you some time until you get help.

An older child should definitely carry an epi-pen around and be instructed in how to use it, if they have a history of a severe reaction to food allergy.  All the caretakers of the child should have it, meaning the school, the parent.  One should be kept in the car.  Keep one in the child's bookbag.  I also instruct a lot of patients to carry around a Medic Alert bracelet, which says that "This child is severely allergic to such-and-such."  So that if the child is found unconscious, somebody may realize this may be an allergic reaction to foods.

PAUL MONIZ:  One of the most difficult things that people have to deal with is not knowing exactly what's in their foods, especially when they go out to dinner.  This becomes a major problem with people, with parents who have children, even with adults.  They don't what's in the foods, because they're ground up, and oftentimes the waitstaff doesn't know every ingredient.  How do you safeguard against getting allergic reaction?

HEIDI ZAFRA, MD:  For bought foods, prepackaged foods, it's very, very important for parents and older children to read labels, because, for example, peanuts.  Peanuts are hidden in many foods like Plain M&Ms, cheese crackers, Raisinets.  The peanut serves as a binder to make the chocolate stick together, and it's made in the same factory, the same machinery as the M&Ms Peanut.

For restaurants, you really have to specify with the owner, the manager or your waiter that you are specifically allergic to shellfish.  They must use a fresh grill, fresh oil, and not use the same spatula to spear the different foods, especially in Chinese restaurants, because they are very notorious for putting shrimp in a lot of foods, and peanut sauce.

PAUL MONIZ:  Do you find that fairly common, that even people who can generally control their allergies will have a flare-up as a result of going to a restaurant and eating a mystery food, so to speak?

MORRIS NEJAT, MD:  Sure.  It happens a lot.  I tell patients that are very allergic that they.  I tell a lot of patients: Don't eat in Chinese restaurants, specifically.  Because oftentimes, there's a language barrier, where the waitstaff may not take it seriously.  The foods are all mixed, and they're all made in the same pan.  Even if they don't put shellfish or peanuts in a specific dish, it may have been in a previous dish in high enough concentrations.

There have been reports of patients that have had a systemic severe reaction to peanuts, when the person three rows up from them in a plane has been eating peanuts, and just smelling the fumes.

PAUL MONIZ:  Really?  So they're that sensitive.

MORRIS NEJAT, MD:  They can be that sensitive.

PAUL MONIZ:  What about strange reactions when people eat food?  First off, they feel tingly and hot and cold.  What would that mean?

MORRIS NEJAT, MD:  That could be an allergic reaction. That could just be some foods cause you to have flushing, like MSG, give you headaches.  It may not be a classic food allergy, rather than a food intolerance.

PAUL MONIZ:  What about someone whose nose runs when they eat food?  Be it hot food or just almost any food?  They just have a runny-nose reaction.

MORRIS NEJAT, MD:  That's called vasomotor rhinitis.  That's more of a nervous system response than an allergic response.  That can be controlled with certain nose sprays or by avoiding these foods.

PAUL MONIZ:  What foods can trigger that?

MORRIS NEJAT, MD:  Like you said, hot, spicy foods.

PAUL MONIZ:  Is there any introduction therapy that can help patients with food allergies?  For instance, if they don't want to take shots, let's say.  Does it help to introduce the foods that they might be allergic to in small amounts and then gradually increase?  Can you build up, or no?  If you're allergic, that's it.

MORRIS NEJAT, MD:  Pretty much.  You can't even give shots to it.  There are some trials going on at the major teaching hospitals, where they try to desensitize severely allergic patients to, say, peanuts, which is so prevalent in our society.  They've seen some success, but also they've seen some very severe reactions, so I think it's a long way off from being introduced by the FDA.

The main risk factors for severe reactions to food allergies have been shown to be a previous systemic reaction and/or a history of asthma.  Those are the patients that usually die when they accidentally ingest a substance.  Most patients that die of food allergies know what they're allergic to and are actively trying to avoid it, but they eat it by mistake.

If you're ever eating something, and you're not sure what is in it, and all of a sudden your mouth feels a little bit tingly or unusual or something is going on, spit it out right away, get your epi-pen ready, and rush for help immediately.

PAUL MONIZ:  When you get help, what happens to you at the hospital?  What do they give you?

MORRIS NEJAT, MD:  Usually what they would do is, they would give you one or more doses of adrenalin.  They would give you some sort of antihistamine shot or injection through your vein, and then they would give you oral steroids to decrease the late phase.  And any other sort of measures that you may need, such as intravenous fluids.

PAUL MONIZ:  Left untreated, how will the patient, if the patient were to die, what would happen physically?

MORRIS NEJAT, MD:  Basically they go into anaphylactic shock.  It's similar to a patient that gets stung by a bee, who's allergic to a bee.  You would see them maybe break out in hives, shortness of breath, not able to breathe.  Your blood pressure would drop, you may faint, and then you go into shock, basically.

PAUL MONIZ:  Heidi, let's bring you back into this if we could.  Talking for a moment about children and their parents.  Kids especially want to eat what they want to eat.  They're not always in their parents' presence.  They go to parties, they're with their friends, and they don't always take it so seriously.  What do you instruct parents to do to impress upon their children that they really need to be careful?

HEIDI ZAFRA, MD:  There is an organization called the Food Allergy Network.  The Food Allergy Network gives you material, they have cartoons for the kids.  One particular cartoon which I like is The Elephant Who Could Not Eat Peanuts.  Basically it tries to make a child understand, in simple terms, the dangers of trying to eat the food that they're allergic to.

Really, once a child is six, seven, they're old enough to understand that they can't eat these foods.  The parents really should supervise and try to explain why they shouldn't be accepting M&Ms from a friend in the cafeteria, or trying a peanut butter sandwich.  In fact, I think schools now have stricter regulations, like the peanut allergic kids sit in one table and they're supervised so that they don't accidentally ingest any of these foods.

All the other foods, basically, like the egg or the milk, what happens is, later in life, if they avoid it for a year, they may be able to tolerate it, as what Dr. Nejat said.  So those aren't really the problem.  It's really just the peanuts and the shellfish, where you really have to be very, very careful.  And of course they need their epi-pen with them.

PAUL MONIZ:  Some very good advice.  We appreciate your time.  Dr. Heidi Zafra, thank you for joining us.  And Dr. Morris Nejat, for your time.  Again, as our guests mentioned, the most important thing is to ask questions.  If you don't know what's in the food, ask.  And read labels.