House CallDec/Jan 2011 Issue

Research Roundup: Peanut Allergy, Food Dye, Celiac and Autism

The latest medical news for people with allergies and food sensitivities

Young boy getting his teeth examined.

©iStockphoto/Thinkstock 2010

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Celiac disease is highly associated with dental enamel defects in childhood, according to an article in the Journal of Clinical Gastroenterology.

Two independent dentists examined the teeth of 136 patients (67 with biopsy-proven celiac disease and 69 non-celiacs) and found that those with celiac disease had significantly more enamel defects. However, the findings were confined to children in the study. Eighty-seven percent of children with celiac disease had enamel defects compared with 33 percent of the control group.

Researchers attribute the enamel defects to the onset of celiac disease during enamel formation, which begins before birth and continues into early childhood. A link between canker sores in the mouth and celiac disease was also noted.

Given the strong association in this study and similar ones previously observed in European populations, the researchers recommend all physicians assess the mouth, including the teeth, during patient exams. Enamel defects, which typically can include tooth discoloration (white, yellow or brown spots) or pitting, may provide impetus for pursuing diagnostic testing.

Allergies Skyrocket

Rates of peanut and tree nut allergies among children have more than tripled in just over ten years, report researchers from the Jaffe Food Allergy Institute at Mount Sinai School of Medicine in New York. The team surveyed more than 5,000 U.S. households by telephone in 2008 and compared results to a similar 1997 survey. They found peanut allergy increased from 0.4 percent in 1997 to 1.4 percent in 2008, while tree nut allergy rose from 0.2 percent to 1.1 percent. Researchers aren’t sure why the alarming increase but say “clean living,” reducing exposure to infections and thereby freeing up the immune system to attack harmless proteins in food, pollens and animal dander, could be to blame. Allergy increases were not found in adults.

Researchers also evaluated the prevalence of sesame allergy for the first time in this survey. Just 0.1 percent of adults and children reported sesame allergy. However, the researchers state that this allergy’s severity and its frequent occurrence with peanut or tree nut allergy should be noted.

Peanut and tree nut allergies represent a significant health burden, the researchers conclude, adding that better strategies for prevention and treatment are urgently needed, particularly if prevalence continues to increase over time.

In related research, the first nationwide study to determine the prevalence of severe food allergies in Canada was recently completed. Using a similar telephone survey, researchers asked participants about peanut, tree nut, fish, shellfish and sesame allergies. They classified the allergies as perceived (based on self-report), probable (based on convincing history or self-report of physician diagnosis) or confirmed (based on history and evidence of confirmatory tests).

The prevalence of perceived peanut allergy was 1.0 percent; tree nut, 1.22; fish, 0.51; shellfish, 1.60; and sesame, 0.10. The prevalence of probable allergies was slightly lower in each category. Estimates of confirmed allergies were even lower, across all allergens, due to the infrequency of confirmatory tests and difficulty obtaining results when performed. Disparities between perceived and confirmed allergies may help explain variable prevalence estimates reported in the literature, as well as point to a need for increased use of confirmatory allergy testing, say the researchers.

Both studies were published in the Journal of Allergy and Clinical Immunology.

Help for Peanut Allergy

Preliminary work with oral immunotherapy suggests it may be a safe and effective way to protect some peanut allergic children from accidental peanut exposure. Oral immunotherapy involves giving food-allergic patients escalating amounts of powdered food proteins to increase their tolerance. In the study, an international research team from the United States and Germany gave 23 peanut-allergic children small doses of crushed peanut, increasing the dose every 2 to 4 weeks. They found that using a long-term buildup (approximately seven months), 61 percent of children reached the target dose of at least 500 mg of peanut, enough to provide significant protection against accidental ingestion, say researchers.

However, adverse allergic reactions were relatively common during the treatment, causing several children to drop out of the study. Significant work is needed before oral immunotherapy is ready for clinical use.

The study appeared in the Journal of Allergy and Clinical Immunology.

Good-Bye to Dye?

Several of the most widely used food dyes, including Red 40, Yellow 6 and Yellow 5, may pose health concerns and should be banned, says the Center for Science in the Public Interest (CSPI) in a report published in June 2010. According to the report, hypersensitivity reactions, allergies and behavioral problems in children may be linked with certain food dyes. Such effects led the European Union to recently require a warning label on most dye-containing foods: "May have an adverse effect on activity and attention in children.”

The dyes may also be carcinogenic, says CSPI, pointing to animal studies that suggest the dyes—and other chemicals bound to them—can cause cancer. The group adds that most of the studies have been limited to individual dyes, which may not paint a full picture of the risks. Most foods and diets actually contain mixtures of dyes (and other ingredients) that might lead to synergistic adverse effects.

Although not all experts support CSPI’s stance on a ban, natural dyes are gaining ground. Annatto, caramel, blueberry juice concentrate, carrot juice, beta carotene, paprika, turmeric, grape skin extract, beet juice, purple sweet potato, corn and red cabbage are some alternative dyes to look for on ingredient labels.

Celiac and Autism

It’s unclear if there’s a relationship between celiac disease and autism, particularly in children with both autism and gastrointestinal disease. To investigate a potential link, researchers at the Pfeiffer Treatment Center in Warrenville, Indiana, tested the blood of 55 autistic children who have a chronic digestive disease for tissue transglutaminase IgA and IgG, a common celiac disease screening test used as a marker for celiac disease in the study (the test alone doesn’t diagnose celiac disease). Sixty-seven children served as a comparison (control) group.

Researchers found no significant difference in the levels of the celiac markers between children with and without autism, suggesting there is no link between celiac disease and autism, even among those with autism and gastrointestinal disease. However, the work is preliminary, researchers say.

In a subset of participants, the team examined whether the presence of the same celiac markers correlate with low levels of Alpha-1 Antitrypsin (AAT) or anti neutrophil cytoplasmic antibodies (ANCA), factors in the blood that may be relevant to celiac disease and autism. A significant relationship between ANCA and IgG—both autoantibodies—was observed among the autistic children. The preliminary finding supports the hypothesis that there is a generalized autoimmune dysfunction in autistic children with gastrointestinal disease. This may help explain why general immune suppressing therapies, such as steroids and anti-inflammatory drugs, can successfully treat some autistic children with gastrointestinal-related illness, say the researchers. Additional study is needed.

The work appeared in Immunology and Immunogenetics Insights.

Medical writer Christine Boyd lives in Baltimore.

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