Posted tagged ‘food allergy’

The myth of iodine allergy

September 28, 2015

The Pediatric Insider

© 2013 Roy Benaroch, MD

 

Since every second of my life, and then some, seems preoccupied with the transition to the New and Improved ICD-10 code set — I can’t imagine how I lived so long without being able to code for macaw attacks – I’ve had no time to write anything new. So today you get a refurbished, classic post. And by classic, I mean old. I put a new photo somewhere in the text to freshen it up, so I promise it’s worth a read. Enjoy!

 

One of the goals of this site—along with soliciting donations and letting me write and publish goofy stuff—is to promote good, solid science-based medical information. If you’ve been around, you know I don’t go for made-up-stuff. And I especially don’t like it when it’s other doctors spreading the misinformation.

Have you had a reaction to intravenous contrast dye during a CT scan or other exam? Have you been told you’re allergic to iodine, and that you should avoid seafood?

Wrong wrong wrong. You’re not allergic to iodine. And you can almost certainly have seafood—you’re no more likely than anyone else with any allergy to be allergic to seafood, or salt, or dairy products, or anything else that contains natural or added iodine. The only thing you may need to avoid is that same kind of IV contrast dye in the future—though even then, it can probably be safely used with simple premedication.

Iodine is a natural element. It is essential for life—if you didn’t have any, your thyroid gland couldn’t work, and you’d get sick and die. Iodine is found especially in seafood, but also in some vegetables and dairy products (especially if the cows were grazing on land where the soil was rich in iodine.) In many countries, including the USA, salt is routinely fortified with iodine to prevent thyroid disease.

Allergies are almost always triggered by proteins—big, honking, complex molecules made of chains of amino acids—or other big molecules. Someone who’s had a reaction to IV contrast dye has not reacted to the iodine, but to the other constituents of the dye. People who’ve had these reactions may need to be premedicated or use a different, low-reaction type of dye is used in the future if they need further studies.

These are dangerous macawsIt may be that people who’ve had reactions to IV contrast might also have a food allergy, and that food allergy might even be to seafood. But there is no increased risk of seafood allergy than to allergy to any other foods. You might be allergic to seafood or milk or eggs or peanut or… nothing. But you’re not allergic to iodine.

Refs:

http://www.ncbi.nlm.nih.gov/pubmed/20045605

http://www.ncbi.nlm.nih.gov/pubmed/16541971

Eat peanuts during pregnancy to prevent allergies

April 14, 2014

The Pediatric Insider

© 2014 Roy Benaroch, MD

It wasn’t that long ago that the usual advice to prevent food allergies was to avoid or delay certain foods. Now, the pendulum has fully swung over to the other side. As more and more evidence accumulates, it’s becoming clear that the way to prevent allergy is by exposures, not avoidance. Immune systems need to see allergens early to develop tolerance.

I’ve recently written about studies that show that at least some cases of peanut allergy can be overcome by gradual, graded consumption of peanuts. We also know that some food allergies are less likely to occur if babies eat things like grains and eggs beginning at around four to six months of age (this is likely true for other allergens, like peanut and fish, though the evidence isn’t as strong.) Now a new study shows that exposures from before birth can help a developing baby’s immune system learn to tolerate food proteins.

Researchers in Boston prospectively followed 8200 children, born from 1990 to 1994. Among the group, 140 became allergic to peanut or tree nuts (about 2%, which may strike you as low—but that’s the rate of allergy when strict criteria and independent assessments are used rather than parental reports alone.) They then compared the maternal diets during pregnancy between children who became allergic, versus those that did not. Among moms who themselves were not allergic to peanut, eating more peanuts and tree nuts more frequently during pregnancy was associated with a dramatically decreased risk of later allergy in their offspring. The reduced risk was probably in the range of 25-75%. Not bad for an intervention that’s cheap and safe.

Of course, moms who are themselves peanut allergic should not consume peanuts. In the study, nut-allergic moms who ate nuts were not more or less likely to have nut-allergic children than nut-allergic moms who avoided nuts.

The immune system is complicated, and the development of food and other allergies depends both genetic and environmental factors. But it’s clear that we can’t just run away from foods in the hopes that we won’t become allergic. Moms who are not allergic to food should enjoy a rich, varied diet throughout pregnancy, including peanuts and tree nuts. Nursing moms should eat what they’d like. Starting at four to six months, little babies should start complementary foods, including basically anything they’d like off of their parent’s plate, mushed up and tasty. Want to avoid food allergies? Eat.

What should a seven-month-old baby eat?

March 31, 2014

The Pediatric Insider

© 2014 Roy Benaroch, MD

Naomi wrote, “I’d like to start letting my 7 month old try some of the foods we’re eating during dinner. He always sits at the table with us and seems fascinated by what we’re putting in our mouths. It seems like most baby books say not to give babies anything with added salt, however, and cooking for adults without salt would ruin dinner. My question: if we’re only talking about home made food, is a little salt really so bad for a baby that’s eating solids? And if it is, at what age can he start eating table foods? I get that the salt levels in processed foods might be too high, but I’ve always thought home made food had much less.”

Listen to your baby—he’s fascinated by what you’re eating, and wants to try it. As long as the food isn’t a choking hazard, let him enjoy!

We think of “traditional” baby food as the stuff in boxes and little jars and little plastic tubs. Cereal, pureed veggies, pureed fruits—single-ingredient, bland, with minimal salt and other stuff. Of course, this is hardly “traditional” at all. It’s just what the baby food companies have been selling in the developed world for the last 100 years or so. “Traditionally,” once babies started weaning, they ate whatever everyone else ate.

There are a few different reasons why some have recommended sticking with “baby food” for toddler-aged kids. None of them are really very good reasons—and in fact, moving towards “real food” as soon as practical is better for everyone involved.

Naomi asked specifically about added salt. The thinking goes: many of us consume too much salt, which has been linked to hypertension in some genetically-predisposed individuals. So why get Junior used to the taste of salt too early? Won’t that cause him to crave salt later? But there’s no evidence whatsoever that more or less salt at seven months is going to make any difference. Later on, he’ll get used to the kind of meals eaten by everyone else, salted or low salt. There’s no critical window for deciding how salty someone likes their food.

There are also concerns that the early introduction of a mix of foods to youngish babies might increase their risk of food allergies. The truth is the opposite. There’s no evidence that waiting until later than four to six months of life increases the risk of allergy to any foods—not peanuts, not eggs, not fish. Those and any other foods can safely be introduced starting within the usual four to six month window. In fact, there’s some evidence that this earlier introduction can make food allergies less common.

The only significant health concern I have about early “real food” is whether it could be a choking hazard. Early foods should be a mashed-up or pureed consistency that can easily be eaten without teeth. Once Junior can pick up a morsel with his hands, start with soft little bits (about the size of the last part of his thumb, past the knuckle.) It’s messy, it’s fun, and it’s the best way for Junior to learn about textures and flavors. Eat as a family, and eat the same things. Yum!

Fixing peanut allergy by eating peanuts

February 20, 2014

The Pediatric Insider

© 2014 Roy Benaroch, MD

Peanut allergy can be a big deal. And most children who are allergic to peanuts will not outgrow their allergies. Avoidance has been the main way to treat peanut-allergic people, but that doesn’t always work. Peanuts can sneak into foods, especially with young children who may not be able to monitor their intake closely. What if there were an easy way to “cure” peanut allergy?

Researchers in the UK published a study last week looking at the safety and effectiveness of oral desensitization. They enrolled 99 children from age 7-16, all of whom with documented real peanut allergy by prior oral challenge (ie, they had all had serious, immediate reactions to peanut under controlled conditions in the past.) They were randomized into two groups. The control group was told to continue avoiding peanuts. The kids in the intervention group were given a daily dose of oral peanut flour, starting with a tiny dose of 2 mg, and working up every two weeks to a maximum dose of about 5 peanuts worth of protein.  Of the 49 children randomized into the intervention group, 6 withdrew from the study—four of whom because of reactions to the peanut. One child required one dose of epinephrine during the study because of a serious reaction. After the study period, all of the remaining participants in both groups had a double-blind, placebo controlled peanut ingestion to see if an ordinary dose of about 10 peanuts could be safely tolerated without a reaction.

Of the children in the control group, who had been told to just continue to avoid eating peanuts, none could then tolerate a peanut ingestion (46 of the 46 who were still participating at that time reacted.) In the exposure arm, about 85% of the participants who completed the oral desensitization scheme were able to tolerate eating peanuts. After the study period, most of the children who had been randomized into the control arm were offered oral desensitization, and they ended up doing about as well.

Though oral desensitization worked most of the time, some questions remain. It’s not known how long these children will remain desensitized—they may need to continue oral exposures daily to prevent relapse back into clinical allergy. And about 20% of the original intervention group didn’t complete the study for a variety of reasons, some of whom because they couldn’t tolerate the treatment itself. But for most of the children who could complete the therapy, oral desensitization seems very promising.

It makes sense, too—we know that early oral exposures to foods seems to prevent at least some kinds of allergies, and that policies that encouraged delaying foods (especially past six months of age) probably led to increased allergy.

However: this is still an area of active research. Please do NOT try this on your own. The research groups had specific protocols using purified proteins, and though it’s likely that widespread use of this technique will lead to a simple, home-based regimen, we’re not quite there yet. If your child has peanut allergy and you’re interested in pursuing oral desensitization, speak with a board-certified allergist about enrolling in a trial or learning more about this before you give your child any peanut.

edit 2/21/2014 — fixed broken link to study

Introducing solids to baby: Which ones, and when?

March 18, 2013

The Pediatric Insider

© 2013 Roy Benaroch, MD

Anna posted: “I have a question about starting solids and grains. I am starting my 6 month old on solids. A friend recently told me that babies younger than 1 year cannot digest grains as they don’t have the necessary enzymes. Is there any truth to this? Also, one of the pediatricians in our practice told me we can start eating red meat- isn’t it too early?”

There’s been a big change in the thinking about solids over the last ten years or so. In the past, it had been recommended to delay certain foods—the ones thought to be the most likely allergens—until certain ages. The thinking was that this would somehow prevent allergies. You can still find these elaborate schedules on the internet: avocado at 33 weeks, egg whites at 34 ½ weeks, chopped venison au poivre at 36 weeks, all very specific, and all very strict. It turns out that was all nonsense, too.

A 2008 AAP statement threw all of those recommendations out of the window, pointing out that there was never any evidence that delayed introduction of any foods decreased allergy risk. In fact, evidence was accumulating from here and abroad that foods started earlier were LESS likely to become foods that children would become allergic to. Cultures with earlier consumption of peanut, for instance, had far less peanut allergies than places where peanuts were not part of an infant diet.

Now, the allergists have formally agreed, with their own recommendations from the American Academy of Allergy Asthma and Immunology (the AAAAI—how do they pronounce that?) Start complementary foods, any ones you’d like, at 4-6 months. That could include egg, peanut butter, fish, berries, you name it. There is no reason to delay certain foods—that’s quite unlikely to prevent allergy, and might well make allergy more likely.

Some further evidence-based guidelines about food allergies from the AAP and AAAAI: there is no reason for pregnant women to avoid any foods, unless they themselves are actually allergic. (There are foods to avoid for infection reasons, I’m only talking about allergy issues here). And breastfeeding prevents allergy, too.

Anna, whatever you’ve heard about babies lacking enzymes to digest grains, that’s just weird internet rumor. Babies do fine with ordinary grains like rice, oats, barley, and wheat (though they don’t need anything but breast or formula for the first 4-6 months of life.) And meat is fine to introduce at 4-6 months—in fact, in many countries, meat is a first weaning food, before cereal. It’s easy to digest and a good source of protein and iron.

So: these firm rules about exactly what and when to feed babies can be ignored. You do need to avoid choking hazards (no peanuts, no hot dogs for infants!), and you need to avoid raw unprocessed honey until 12 months to prevent botulism. Other than that, starting at 4-6 months, your baby can taste what you’d like her to taste. Yummy!

Nuts. Allergy!

November 18, 2008

Allison, whose name was ranked #47 among newborn girls in 2007, has a question about nut allergy: “We just (inadvertently) figured out that our 6 year old son is allergic to pecans. His reaction isn’t life threatening — his eyes swell up and get itchy. What should we do (other than obviously teach him to not eat pecans)? Do we need to get him tested officially? Tell the school? Anything else?”

The first step, as you said, is to avoid pecans: teach him not to eat them, and to ask adults about the nut contents of food, and get used to reading labels on things like cookies or brownies. Since he might not be able to tell the difference between a pecan and another nut by just looking, it’s probably best for him to learn not to eat anything that looks like a nut unless it’s OK’ed by you. Definitely, tell the school, tell grandma, and tell any of his friend’s parents before you drop him off for the afternoon.

You should also travel with Benadryl at all times, and keep some in your house. Make sure grandma has some too. Talk with your pediatrician about specific dosing and usage of medications, and whether you ought to carry injectable epinephrine. People at the highest risk for life-threatening nut allergies are those who have had any sort of nut reaction in the past and who have a history of asthma or wheezing.

Allergy testing can be useful to see if he’s also allergic to other tree nuts, or to peanuts (there are often cross-reactions.) If he’s already had peanuts and other kinds of nuts, and never reacted, there is no need for testing. But if you’re not sure if he’s had different kinds of nuts, it’s a good idea to do a “nut panel” to see if he’s likely to be allergic to other nuts.

Visit the Food Allergy & Anaphylaxis Network for more info—it’s an excellent, non-profit web resource with good info on nut and other food allergies.