Archive for the 'Food Allergy' Category

Peanut Tainted Cumin

February 26, 2015

The FDA has warned that peanut allergen has been detected in several cumin-containing products.  Individuals allergic to peanut should avoid products containing cumin.  Many have been recalled, including spice mixes and marinades.  Whole Foods has recalled more than 100 products and Goya has recalled some brands of black bean soup.  Individuals with severe peanut allergy need to be particularly careful when eating in restaurants that use cumin as an ingredients including Indian and Mexican restaurants.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person. If you have a medical problem, please contact your doctor.

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Do Not Delay: More Evidence Against Delaying The Introduction Of Foods In Infants

April 23, 2011

There is increasing evidence that delaying the introduction of foods in infants contributes to an increased risk of developing food allergy.  A recent study of 2,589 infants showed that delaying the introduction of egg into the diet of infants results in an increased risk of egg allergy.  The odds ratio of developing egg allergy was 3.4 in the group that had egg introduced into the diet at greater than 12 months of age compared to those with egg introduced at 4-6 months of age.  An odds ratio greater than 1 means that the outcome is more common in that group.  See related  blog entries from 12/15/10 and 4/18/10.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.

Guidelines for the Diagnosis and Management of Food Allergy in the United States: A Summary of the New NIAID-Sponsored Expert Panel Report

December 15, 2010

The new NIAID-sponsored Guidelines for the Diagnosis and Management of Food Allergy in the United States were released on December 6, 2010.  I thought it might be helpful if I provided a summary of the highlights of the report.  The full guidelines can be downloaded on the NIAID website at http://www.niaid.nih.gov/topics/foodallergy/clinical. 

The release of these guidelines has received significant media attention, although there is really very little, if any, new information included in them.  Much of the most recent information in the literature regarding such issues as component testing, extensively heated egg and extensively heated cow’s milk as well as decision trees based on IgE Immunocap blood testing or skin testing for performance of oral challenges in food-allergic children is only alluded to and unfortunately not really addressed in the guidelines. 

The following is a list of what I consider the most pertinent and clinically relevant statements and recommendations in the guidelines.  There is much more information in the full report.  I have included in parentheses additional information not included in the guidelines but that I think may be of interest.  This list is in no particular order of importance.

1. Atopic Dermatitis/Eczema:  Up to 37% of children under 5 years of age with moderate to severe atopic dermatitis have IgE mediated food allergy.  Food allergy testing should be considered in this group of children.  Infants who develop atopic dermatitis within the first 3 months of life are most often allergic to cow’s milk, egg and peanut.  Mutations of the skin barrier protein filaggrin, seen in a subset of patients with atopic dermatitis, may increase the risk for transcutaneous food allergen sensitization when infants come in contact with food allergens.  (There are reports in the literature that suggest this is especially true if the food is introduced to the immune system through the skin prior to exposure through the GI tract.  Initial GI tract exposure is more likely to induce tolerance.)

2. Severity of an Allergic Reaction: The severity of a future reaction to a food allergen cannot be accurately predicted by the severity of a past reaction, or by the level of specific IgE or the size of a skin prick test wheal.  One study showed that 44% of patients with documented peanut allergy who did not have an initial reaction that was life threatening, had subsequent reactions that were potentially life threatening.  (The higher the level of specific IgE and the larger the skin prick test wheal, the more likely it is that a patient will have clinical food allergy.  However, the severity of the allergic reaction associated with that allergy can not be predicted based on these test results.) 

3. Diagnosis of Food Allergy: The gold standard for the diagnosis of food allergy is a double blind placebo controlled food challenge, but single blind or open challenges may be considered.  (From a practical perspective, blinded placebo controlled food challenges are really only done in a research setting.  I perform open challenges in the office.)

4. Diagnosis of Food Allergy: Skin prick test results or food-specific IgE alone cannot be used to make a diagnosis of clinical food allergy.  They only indicate sensitization.  The test results must be considered within the context of a comprehensive history.  To diagnose a clinical food allergy, or rule it out, in a situation where there is a positive test result and no history of reaction to the food, an oral challenge must be performed.  (The problem of what to do with a positive result in a child who has never consumed the food allergen tested is a difficult one and underscores the need to do history-guided testing and to be cautious when ordering IgE Immunocap tests.  Unnecessary avoidance of foods to which a child is sensitized, but not clinically allergic, can lead to nutritional problems.)  

5. Gastrointestinal Issues Related to Food Allergy: Food allergy should be considered in infants and young children with eosinophilic esophagitis, enterocolitis, enteropathy and allergic proctocolitis.

6. Natural History of Food Allergy: The guidelines provide information on the natural history of food allergy in infants and children and at what age infants and children might outgrow a clinical allergy to foods such as cow’s milk, egg and soy.  The guidelines provide very little specific information on when to consider an oral food challenge in a child with a documented allergy to these foods.  (There is information in the literature referencing food-specific IgE levels and skin prick wheal sizes that address this.  My approach is to evaluate this information in conjunction with a comprehensive history and make a risk-benefit assessment on whether and when to do an oral challenge under supervision in my office, on a case by case basis.)

7. Cross Reactivity of Foods: The guidelines provide statistics on allergic cross reactivity of various foods such as the fact that at least 12% of individuals with tree nut allergy are clinically allergic to more than one tree nut.  It also states that 35% of infants with one food allergy develop an allergy to another food.  However, little specific guidance is given as to whether or not to do additional food allergy testing in infants and children with a documented allergy to a specific food.  (I approach this on a case by case basis and generally do some additional testing in children with a documented allergy to a specific food.  I generally confine additional testing to cow’s milk, soy, egg, wheat and peanuts as well as the foods that significantly cross react with the food to which the child is documented to be allergic.)

8. Breat Feeding: The guidelines recommend exclusive breast feeding for all infants for the first 4-6 months of life.  For infants at risk of developing food allergy (first degree relative with history of atopy including allergic rhinitis, asthma, atopic dermatitis or food allergy), the guidelines recommend hydrolyzed formula for the first 4-6 months if breast feeding is not possible.  Soy formula as an alternative is specifically not recommended.  (This is consistent with the American Academy of Pediatrics recommendations published in Pediatrics in January 2008: Pediatrics 2008;121;183-191)

9. Prevention: There is no evidence to recommend delaying introduction of any specific solid food, including those considered highly allergenic such as eggs, fish or peanut, beyond 4-6 months of age.  This applies to infants and children in general as well as infants at risk for food allergy.  There are no specific recommendations given for how to proceed in a child who already has one documented food allergy.  (This too is consistent with the American Academy of Pediatrics [AAP] recommendations published in Pediatrics in January 2008.   These recommendations are different from the AAP recommendations published in 2000 where a schedule of delayed introduction of foods was recommended.  The change in this recommendation is based on epidemiologic data indicating that there is no benefit in delaying the introduction of developmentally appropriate foods and even some data pointing toward an increased incidence of allergy when the introduction of food is delayed [see January 12, 2010 post on this blog as well as other food allergy posts on this blog]. )

10. MMR Vaccine: The MMR (measles, mumps and rubells) vaccine is safe for children with egg allergy, even for those with severe reactions.  (This is consistent with the most recent AAP recommendations.)

11. Influenza Vaccine: The guidelines state that there is insufficient evidence to recommend administering influenza vaccine routinely in patients with a history of hives, angioedema, allergic asthma or systemic anaphylaxis resulting from allergy to eggs.  The guidelines highlight that in one recent study 5% of patients with egg allergy and negative skin prick test results to influenza vaccine had systemic reactions to vaccination.  The guidelines discuss various approaches to giving influenza vaccine to children with egg allergy.  (I address this in my practice on a case by case basis doing a risk benefit analysis based upon the specific history and the results of IgE Immunocap and skin prick test results and an extensive discussion with the parents.  I have almost never had a patient who I have chosen to vaccinate after this type of comprehensive evaluation develop a systemic reaction to the influenza vaccine.)

12. Education: The guidelines state that people with food allergy and parents of children with food allergies need to be educated on how to properly read and evaluate a nutritional label.  The guidelines specifically recommend that people avoid foods with precautionary labeling such as “this product may contain trace amounts of allergen”. 

13. Treatment:  Epinephrine is the drug of choice for anaphylaxis and should be administered as first line therapy.  Fatalities from anaphylaxis are associated with delayed administration or improper use of epinephrine.  The use of antihistamines is the most common reason reported for not using epinephrine.  The highest risk groups for food allergy related anaphylaxis are adolescents and young adults, people with a prior history of anaphylaxis and patients with asthma.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.

Extensively Heat Egg and Egg Allergy

October 25, 2010

Egg allergy is one of the more common food allergies in children under the age of 3 and is especially common in children with atopic dermatitis.  Most children will outgrow egg allergy, but  it is often difficult to determine exactly when that is going to happen.  Although it is relatively easy to avoid whole eggs in the form of scrambled eggs, omelettes, souffles and quiche, it is more difficult to avoid eggs that are present in baked goods such as cookies and cakes.   

Many children with egg allergy can tolerate extensively heated eggs in oven baked goods, even though they react to cooked or partially cooked eggs in other forms.   Recent research has shed some light on how doctors can differentiate those who are able to tolerate egg in baked goods and those who can’t.  There are over 20 different glycoproteins that make up the allergenic component of egg white.  Ovomucoid is the glycoprotein associated most closely with reactions to extensively heated egg as it is highly stable in heat.  

There is a blood test available that can measure IgE (allergen antibody) against ovomucoid as well as other egg white glycoproteins.  The level of IgE can help your doctor determine if it is reasonable to do an open challenge with extensively heated egg.  The higher the level of IgE against ovomucoid, the less likely someone is to tolerate egg in baked goods.   Some “cut off values” for challenges have been established based on research looking at IgE levels in children with egg allergy.  IgE values can also be used to determine if it is appropriate to do an open challenge with whole egg as well.

Please note that challenges should always be done in a doctor’s office and never at home.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.

Peanut Allergy: Testing Update

June 29, 2010

Peanut allergy is generally confirmed through allergy skin testing and/or blood testing looking for peanut specific IgE.  Usually someone suspects that they or their child is allergic to peanuts because of specific symptoms that have occurred with exposure, and testing is done to confirm the diagnosis.  

There are situations however, where a child is tested for peanut allergy with either a skin test or a blood test because they have other food allergies and the parent is concerned about the possibility of also having peanut allergy.  Often this occurs before the child has ever eaten peanuts.  If this kind of testing comes back positive, it means that the child is making allergen antibody (IgE) against peanut, but it does not necessarily mean that the child will have clinical symptoms upon exposure.  

A recent study has provided some insight into what percentage of children with positive testing and no history of an allergic reaction to peanuts, actually have clinical allergy to peanuts.  The study did allergy testing in a cohort of children followed from birth.  The study found that 11.8% of children in the cohort had positive testing for peanut allergy.  An extensive analysis of the children with positive testing, including further testing and oral challenges, revealed that 22.4% of those with positive testing and no history of  having a reaction to peanuts, actually had clinical peanut allergy.  So, from this study, we can expect that about 1/4 of children who test positive to peanuts before ever consuming peanuts, will have true clinical peanut allergy.    A supervised challenge in a doctor’s office would need to be done in order to determine if a child is really clinically allergic.  Not all children are candidates for a challenge however.  This would be determined by the allergist based upon an evaluation of the skin or blood test results.  Depending on the level of positivity of the results, some children would not be considered for a challenge.

Peanuts consist of several different allergens.  The testing that is usually done commercially looks at peanut specific IgE, but does not test for each specific peanut allergen.  The study mentioned above looked at each separate peanut allergen and tried to correlate specific peanut allergens with clinical peanut allergy.  The study found that those children with positive testing to the peanut allergen called Ara h 2 were most likely to have clinical allergy.  Less than 10% of children with positive peanut specific IgE on general blood testing who could consume peanuts without having a reaction, had positive antibody testing to Ara h 2.  These results do need to be confirmed, but they are extremely interesting in that they point toward more specific testing for allergens yielding more specific answers with regard to the clinical relevance of a positive test.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.

Food Allergy And Skin

May 3, 2010

There are many in the medical profession who do not think food allergy is a major cause of eczema/atopic dermatitis.  That might be true for adults, but about 37% of children with eczema have at least one food allergy.  If you look at the statistics in reverse, you find that about 90% of children with food allergy have eczema.   In general, it is worthwhile to do food allergy testing on an infant or young child with severe eczema.  If a particular food is identified,  a trial elimination diet should be pursued to determine the impact of the elimination on the condition of the skin.

Another skin condition associated with food allergy is hives.  Hives can occur suddenly in an otherwise well person.  This form of hives is called acute hives.  If hives last more than 6 weeks they are called chronic hives.

A food can be identified as the cause in about 20% of cases of acute hives.  In this setting, if food is responsible, it generally occurs within minutes to 1-2 hours consumption of the food.  A detailed history will often reveal one or more suspect foods and allergy testing should be done to verify whether or not a person is allergic to any of those foods.

When a person has chronic hives lasting more than 6 weeks, a much smaller percentage have an associated food allergy.  Only about 4% of children with chronic hives have a food allergy and about 1.4% of adults with chronic hives have a food allergy.  Whether or not it is necessary to do food allergy testing in the setting of chronic hives depends on the patient’s history.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.

Can Food Allergy Be Prevented In Infants?

April 18, 2010

The development of a food allergy in an infant is often a traumatic event for a parent.  It conjures up all sorts of emotions surrounding the fear of life threatening reactions.  It is disturbing as it means their infant will need to avoid certain foods.  But also, it brings up potential feelings of guilt that somehow the parent, often the mother, did something or did not do something that could have prevented the problem.

The reality is there is little that can be done to prevent a specific food allergy in an infant.  In the 1990’s it was felt that avoidance of certain foods during pregnancy, or the delay of introduction of certain foods in infancy, could potentially reduce food allergy in infants.  However, ongoing research does not support this and, in fact, it is possible that delaying the introduction of foods may increase the incidence of food allergy and not decrease it (see related entry from January 12, 2010).

Here is the bottom line on this subject at the present time:

1. There is no good evidence that maternal dietary restrictions during pregnancy is effective in preventing allergy in infants.   We need more data to be able to know whether dietary restriction during breast-feeding has any impact on the development of a food allergy.  It is important to note, that once an allergy is diagnosed in an infant, there very well might be a need for the mother to avoid certain foods, but that is after the fact, not to prevent the allergy to begin with.

2. For infants with one first degree relative (parent or sibling) with allergic disease, there is evidence that exclusive breast-feeding for at least 4 months decreases the incidence of eczema and cow’s milk allergy in the infant in the first two years of life.

3. For infants with one first degree relative with allergies, exclusive breast-feeding for at least 3 months is associated with a lower incidence of wheezing in infants.  This protection does not extend to a lower incidence of asthma at 6 years of age.

4. For infants with one first degree relative with allergies who are not exclusively breast-fed, the use of extensively hydrolyzed formula may have a temporary protective effect on the development of eczema in early childhood.

5. There is no evidence that delaying the introduction of solid food beyond 4-6 months of age has any significant impact on the development of allergic disease.  This extends to delaying the introduction of foods like fish, eggs and those containing peanuts.

6. Infants whose skin is  exposed to foods either through direct skin contact with foods in the home or through contact with moisturizers or skin products that contains various foods, prior to exposure of that food through actual feeding through the gastrointestinal tract, might have an increased risk of developing an allergy to those foods.  This impact might be higher in infants with eczema.

Please remember that the information in this entry pertains to infants without a specific allergy.  Once an infant has a specific food allergy, avoidance and other measures must be taken in order to avoid potentially severe allergic reactions.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.

Soy Allergy: Will My Child Outgrow It?

April 10, 2010

About 0.4% of children are allergic to soy, making it a common food allergen, but less common than allergy to peanut, cow’s milk or egg.  Since soy is included in many prepared and processed foods, it is a relatively difficult allergen to avoid.

A very common question from parents is whether their child will outgrow a particular food allergy and if so when.  A recent study has shown that although most children outgrow soy allergy at some point, they don’t outgrow it as quickly as previously thought.  The study included 183 children.  Here are the numbers: 25% outgrew the soy allergy by 4 years of age, 45% by 6 years of age and 69% by 10 years of age.

The most common symptoms seen with soy allergy in this study were those relating to the skin such as eczema or hives, and those  related to the gastrointestinal tract such as vomiting, diarrhea, abdominal pain and bloody stools.  Only 5% of children with soy allergy in this study presented with lower respiratory tract symptoms such as wheezing or difficulty breathing.

Children with very high levels of soy allergy as determined by soy allergy specific IgE blood testing, tended to grow out of their allergy more slowly.   It might be helpful for your allergist to follow levels over time to help predict when your child might outgrow the allergy.

It is important to point out that although most people with soy allergy develop the allergy as a young child, adults can definitely develop soy allergy at any age.  In my experience soy allergy in adults is sometimes dose dependent with symptoms only occurring upon consumption of large amount of soy.

Tree Pollen Allergy And Foods: The Oral Allergy Syndrome

April 9, 2010

Certain fruits, vegetables and nuts contain allergens that cross react with tree pollen, specifically the pollen of birch and alder.  These foods include the following:

Nuts: Almond, Hazelnut

Fruit: Apple, Apricot, Cherry, Kiwi, Nectarine, Peach, Pear, Persimmon, Plum, Orange

Vegetables: Carrot, Celery, Fennel, Potato

Although most people with tree pollen allergy can eat these foods without any problem, up to 1/3 of people who are allergic to tree pollen will develop symptoms of what is called the Oral Allergy Syndrome.  The most common of these symptoms is itchiness of the mouth and throat.  A small minority of people who have symptoms of the Oral Allergy Syndrome will have more widespread symptoms seen in other forms of food allergy and it is sometimes difficult to differentiate those who will have just the oral and perioral symptoms from those who have more general allergy symptoms.   Most people with the Oral Allergy Syndrome are only allergic to a few of the foods listed above and not all of them.  In my experience the most common foods to cause symptoms are apples, carrots, cherries and peaches.   Having said that, I do have patients who react to all of the foods.

It is very important to point out that the tree pollen cross reacting allergens in these fruits and vegetables are generally not the major allergens of the foods, but are minor allergens that tend to be heat labile.  That means that these minor allergens lose their effect as allergens with exposure to heat and usually people with this form of food allergy can eat the food in a cooked form without any problem.  So raw apples are a problem, but apple pie, apple sauce and apple juice are usually OK.  It is not unusual for me to see a patient in my office who thinks they are allergic to the skin of the apple or to a pesticide sprayed on the apple because they know they are fine with cooked apple.   Invariably these are people with tree pollen allergy and they are experiencing the Oral Allergy Syndrome.  Also, these allergens tend to be acid labile which means that they lose their effect as allergens when they are exposed to stomach acid.  That is one reason why the symptoms are usually confined to the mouth.

There is some evidence that the common nasal and eye allergy symptoms that people with tree pollen allergy have, may get worse with exposure to these foods in people with the Oral Allergy Syndrome.  I usually recommend that people who have oral itchiness with exposure to one or more of these foods avoid those foods completely in the raw form, especially during the pollen season as it can make their other pollen allergy symptoms worse.

It is important to speak to your allergist about this form of food allergy in order to determine if you need to avoid the foods completely or only in the raw form.  Remember a small percentage of people with this form of food allergy can have more widespread symptoms of an allergic reaction or anaphylaxis with exposure.

Cow’s Milk Protein Allergy: New Approach

April 5, 2010

There is relatively new information on children with cow’s milk protein allergy that is worth mentioning.  Up to 80% of infants and young children with documented allergy to cow’s milk protein can tolerate cow’s milk when it is fully cooked in baked goods.  It is important to note that those who can not  tolerate cow’s milk in a fully cooked form, can have very severe allergic reactions when consuming baked foods that contain cow’s milk.   Parents of a child with cow’s milk protein allergy can consult their allergist to see if a supervised challenge of a baked good containing cow’s milk protein, such as a muffin or cake, is appropriate for their child.  This is NOT something any parent should try on their own outside of the doctor’s office and even a supervised challenge in the doctor’s office is not appropriate for all children with cow’s milk protein allergy.   Again, DO NOT TRY THIS AT HOME!