Decoding Gluten Sensitivity

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“Gluten free” is the new food-fad buzz word with gluten free labels appearing everywhere from salmon to beer.   By some estimates, over a quarter of americans are limiting their intake of gluten.   Entrepreneurial as well as main-line food producers have jumped on the band wagon with both feet, and  have turned “Gluten free” into a $2 billion industry.

And yet, in spite of the explosion in gluten free diets, diet books, and diet products, less than 1% of americans have any real reason to avoid foods containing gluten.  That very real reason is a condition called Celiac disease.  Celiac disease is not a true food allergy but rather a type of  autoimmune disease.   Gluten is a protein found in common grains such as wheat, rhy, and barley.  When this protein in digested in the small intestines, it links up with a chemical in the tissue lining called tissue tranglutaminase.  For unknown reasons the immune system of patients with Celiac disease identifies the linked-up gluten/tissue transglutaminase complex as a threat and produces antibodies to attack it.  This attack of the immune system causes inflammation in the lining of the small intestines resulting in malabsorption as the body’s ability to absorb nutrients, minerals and fat-soluble vitamins is impaired.   If untreated, this can lead to weight loss, diarrhea, and fatigue.  The condition can be reliable diagnosed using a blood test and confirmed by a biopsy of the small intestine.   Treatment is effective but difficult and involves life long, strict avoidance of food containing even trace amounts of gluten. In some patients with Celiac disease, even oats have to be eliminated.

Gluten is not inherently dangerous and is only a problem in those few individuals whose immune system misbehaves by producing anti-gluten antibodies.

A very different condition is wheat allergy.  This is a true food allergy and can result in immediate symptoms after food containing wheat is eaten.   Significant allergy to wheat is also uncommon, affecting less than 1.5% of children, and can be easily diagnosed with an allergy skin test or blood test.

So if celiac disease and wheat allergy are rare conditions, the two conditions combined affecting less than 3% of the population, how did “gluten free” become a $2 billion industry.

Like a lot of diet and health fads that have come and gone, there seems to be a common formula.

  • Start with a kernel of well established truth:

“Gluten causes inflammation” (but only in patients with celiac disease).   “Inflammation is bad and is associated with a number of chronic health conditions that are poorly understood and have no known cure like arthritis, asthma, irritable bowl syndrome, chronic pain, migraine headaches, and fatigue”.

  • Extrapolate from the facts while ignoring a few key points:

“Since gluten can cause inflammation (ignore the fact that this is true in less than 1% of people) and inflammation is the cause of many frustrating medical conditions,  eliminating gluten from your diet may provide relief for those suffering from  headaches, fatigue, chronic pain, irritable bowl syndrome, and headaches by reducing inflammation in your body”.

  • Rely on anecdotal evidence and personal testimonies as confirmation of your hypothesis:

As one web site selling gluten-free products explained:  “You can be sensitive to gluten even though tests for celiac disease and wheat allergy are negative but the only way to know is to go on a strict gluten free diet and see if you feel better”.  However,  following a strict gluten free diet is very hard and many people mess up and so it you don’t feel better, this does not necessarily mean you don’t have a gluten problem, only that you weren’t careful enough”.   In addition, an estimated 40-50% of dietary calories in the american diet comes from carbohydrates, and a large portion of  these carbohydrates come from wheat products.  Because many  junk foods comes from wheat, avoiding wheat can not only result in a significant reduction in daily caloric intake but also in a switch to a healthier, more nutritionally balanced diet with less trans-fat.   And so in the end, patients who report “feeling better” after embarking on a gluten free diet may only be confirming that loosing weight and eating healthier foods can have a positive affect on ones health, and not that they are gluten sensitive.

You may find this recent in Natural Products Marketplace helpful.  http://www.naturalproductsmarketplace.com/articles/2011/01/gluten-free-just-a-fad.aspx

Egg allergy no longer a reason to avoid getting a flu vaccine

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Egg allergy no longer a reason to avoid getting a flu vaccine

From AAAAI:

According to a new paper  published on the American Academy of Allergy, Asthma & Immunology (AAAAI) website, recent studies show that most egg allergic individuals can receive the flu vaccine safely under the care of their allergist/immunologist.

“In the past, persons with egg allergy were told not to get the influenza vaccine because the vaccine contained egg protein and could trigger an allergic reaction. Research in the past year now shows that influenza vaccines contain only tiny amounts of egg protein. Clinical studies proved that the vast majority of persons with egg allergy did not experience a reaction when immunized with the influenza vaccine,” said co-author of the paper James T. Li, MD, PhD, FAAAAI.

Based on the examined research, the authors no longer recommend the practice of skin testing to the seasonal Trivalent Influenza Vaccine (TIV), although it may be useful as an extra level of caution in cases where the patient has a documented history of a past allergic reaction to the vaccine.

Anyone with a history of suspected egg allergy should first be evaluated by an allergist/immunologist for appropriate testing and diagnosis. Patients with a confirmed egg allergy can then receive the vaccine safely using one of two protocols: as a 2-step graded challenge or as a single, age-appropriate dose.

“It is not necessary to withhold influenza vaccination from egg allergic patients. Our recommendations provide two flexible approaches to vaccination. Each approach is backed with recent evidence that it is safe,” according to co-author Matthew J. Greenhawt, MD, MBA. “Most allergists should be able to identify with one of our recommended approaches, and as such should be able to vaccinate their egg allergic patients with confidence.”

The authors do note that the safety of these vaccines in individuals with severe egg allergy needs to be studied further.

Food-allergy fears drive overly restrictive diets

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This is a recent article from National Jewish Hospital in Denver:

Many children, especially those with eczema, are unnecessarily avoiding foods based on incomplete information about potential food-allergies, according to researchers at National Jewish Health. The food avoidance poses a nutritional risk for these children, and is often based primarily on data from blood tests known as serum immunoassays.

Many factors, including patient and family history, physical examination, and blood and skin tests, should be used when evaluating potential food allergies. The oral food challenge, in which patients consume the suspected allergenic food, is the gold standard test.

The researchers conducted a retrospective chart review of 125 children evaluated at National Jewish Health for suspected food allergies. Depending on the reason for food avoidance, 84 percent to 93 percent of foods being avoided were restored to their diets after an oral food challenge. The researchers published their study online in The Journal of Pediatrics on Oct. 29. It will appear in a later print version of the journal. “People with known food allergies, especially those with a history of anaphylactic reactions, should by all means avoid those foods,” said David Fleischer, MD, lead author of the study and Assistant Professor of Pediatrics at National Jewish Health. “However, a growing number of patients referred to our practice are being placed on strict, unproven food-elimination diets that have led to poor weight gain and malnutrition. These overly restrictive diets have been chosen for a variety of reasons, but overreliance on immunoassay tests appears to be the most common cause.”

Immunoassays detect antibodies in the blood to specific foods, which can potentially cause allergic reactions. Interpretation of the results, however, can be tricky. The tests’ ability to predict true food allergy has been validated for only five foods – cow’s milk, hen egg, fish, peanut and tree nuts.

For all other foods, the numbers derived from lab testing are suggestive but not definitive. Low test values suggest that a child’s immune system is sensitized to the food, but not necessarily to the extent that it will cause an allergic reaction. Higher values suggest an increasingly likelihood of true food allergy. None of the tests are 100 percent accurate, however, in predicting clinical food allergy on their own.

National Jewish Health physicians use blood tests as one piece of evidence in their comprehensive evaluation of food allergy. They also carefully evaluate a patient’s history, including any previous reactions to food, the type of reaction, the patient’s age, and the result of skin testing for food allergy. They generally perform an oral food challenge when the evidence is mixed and they want a definitive answer to the food allergy question.

Children in the study were avoiding 177 different foods based primarily on previous blood test results. In many cases, especially those with high test results for egg, milk, shellfish, peanut and tree nut, National Jewish Health elected not to perform oral food challenges. They did perform oral food challenges for 71 foods or about 40 percent of the cases where the clinical allergy was equivocal and it was important to determine whether or not the patient had food allergy. In 86 percent of those cases, the child passed the food challenge and the food was restored to the child’s diet. Overall, 66 of the 177 foods avoided because of blood tests were restored to children’s diets. For the entire study, 325 foods were restored to the diets of 125 children.

“When you are able to restore foods such as dairy products, egg, peanut, wheat, and vegetables to a child’s diet, it improves their nutrition, reduces the need for expensive substitute foods and makes meal time easier for families,” said Donald Leung, MD, PhD, senior author and Edelstein Chair of Pediatric Allergy and Clinical Immunology at National Jewish Health.

The problem can be especially acute among patients with eczema, also known as atopic dermatitis. Research suggests that specific foods can cause flare-ups in about one third of eczema patients. They commonly have high immunoassay tests to a variety of foods, many of which are not truly allergenic. As a result, many mistakenly avoid foods they believe are causing flare-ups, but neglect basic skin care that is vital to improving the eczema. One hundred and twenty of the 125 children in the study had eczema.

Early Introduction to Egg is Best

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Parents worried about childhood food allergies, and who delay the introduction of troublesome foods, could be unwittingly raising their child’s risk.

A Melbourne-based study has found infants who were not introduced to eggs until after their first birthday were up to five times more likely to go on to develop an egg allergy.

This was compared to those who ate their first eggs from age four to six months and, University of Melbourne PhD scholar Jennifer Koplin said, it added more weight to the recent shift in official advice.

“Until recently, Australian and international guidelines recommended that infants with a family history of allergy delay introducing allergenic foods such as egg, peanut and nuts until up to two to three years of age,” Ms Koplin said on Monday.

“Our study suggests that babies who ingest these foods at an earlier age may be less likely to develop food allergies as they grow older.

“It seems that early introduction of egg may protect against egg allergy, while delaying its introduction may put the child at increased risk of developing an allergy.”

The study, published on Monday by the Journal of Allergy and Clinical Immunology, took in 2,500 infants and the timing of their introduction to eggs was checked against those who later developed the allergy.

An early introduction to cooked egg – boiled or scrambled eggs for example – was found to confer more of a protective effect than first consuming eggs in baked form – in cakes or biscuits.

Of babies aged four to six months who were introduced to cooked egg, just 5.6 per cent developed an egg allergy compared with 27.6 per cent of those introduced to cooked egg after 12 months.

A family history of egg allergy did not appear be a factor in those children who went on to develop it, while duration of breastfeeding and introduction to first solids were also ruled out.

Associate Professor Katie Allen, from the Murdoch Childrens Research Institute, said more work was needed to check whether the same was true for other common allergenic foods such as nuts.

“Confirmation that early introduction is protective for other allergenic foods may help better inform parents in the future, and could have the potential to reverse the epidemic of childhood food allergy,” Dr Allen said.

The research forms part of a wider study led by Professor Allen at the Murdoch Childrens Research Institute to track food allergy prevalence and causes among Victorian infants.


Danny Rose, Medical Writer

October 4, 2010

AAP

Will peanut allergy soon be treatable?

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Two studies presented at the 2010 Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI) examine the use of oral immunotherapy in peanut allergic children and continue to add hope that a treatment may be on the horizon.

Both were completed by researchers at Duke University and the University of Arkansas for Medical Sciences. In one, peanut allergic children were randomized to receive either the peanut oral immunotherapy or a placebo. The subjects went through initial escalation, build-up and maintenance dosing. This was then followed by an oral food challenge.

Twenty-three children reached the oral food challenge, 15 had received the oral immunotherapy and eight had received the placebo. During the oral food challenge, the median cumulative dose of peanut tolerated was only 315 mg for the placebo group compared to 5,000 mg (~15 peanuts) for the oral immunotherapy group. In addition, the oral immunotherapy group saw median titrated skin tests decrease from baseline to the oral food challenge.

Median peanut IgE and IgG4 levels were also measured. IgE levels did not change from baseline to the oral food challenge in either group, while IgG4 levels increased from baseline to the oral food challenge in the treatment group.

“We are encouraged by the results of this first blinded, placebo controlled study for oral peanut immunotherapy. The differences in the treatment and placebo group are significant and help guide us to the next studies,” said A. Wesley Burks, MD, FAAAAI, one of the study authors.

In the other study, the researchers looked to identify whether subjects who received the oral immunotherapy could safely ingest peanut after stopping the treatment.

Twelve peanut allergic children who completed all phases of oral immunotherapy, along with meeting certain clinical and laboratory criteria, participated in a final oral food challenge 4 weeks after they stopped receiving the oral immunotherapy. The amount of time the children received the oral immunotherapy ranged between 32 and 61 months.

Nine of the 12 subjects passed this final oral food challenge and now have peanut in their diets.

“We are now trying to identify characteristics in those subjects who were able to stop the therapy to better understand who might be a good candidate for this treatment,” commented Burks.

Over the course of the treatment, peanut IgE levels decreased from the baseline with IgG4 levels increasing. Titrated skin prick tests also decreased from the baseline. These immunologic changes support the development of tolerance.

These studies were presented during the 2010 Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI) on February 26-March 2 in New Orleans. This is reprint from an article located at AAAAI.org.