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House CallAug/Sep 2013 Issue

Research Roundup: Vitamin D, Food Allergy, Celiac Rash in Kids, and More!

Vitamin D and Food Allergy

Adequate levels of vitamin D may protect against food allergy, at least in the first year of life, according to new research from Murdoch Children’s Research Institute in Australia. Infants in the study with low levels of vitamin D (less than 50 nmol/L) were three times more likely to have egg allergy and 11 times more likely to have peanut allergy than those with adequate levels (greater than 50 nmol/L). They were also ten times more likely to have multiple rather than a single food allergy.

The vitamin D status of mothers (before and during their pregnancies) was beyond the scope of the study. However, researchers didn’t detect a difference in food allergy cases between infants whose mothers reported taking vitamin D supplements during pregnancy and those who did not.

In this study, all 344 children with food allergy had their allergies confirmed by gold standard oral food challenge. Over 150 children without food allergy were studied for comparison.

Additional research is needed to determine if correcting too-low levels of vitamin D can help prevent food allergy or promote food tolerance. Currently, the American Academy of Pediatrics recommends a daily intake of vitamin D of 400 IU/day for all infants and children beginning in the first few days of life.

Results were published in April in the Journal of Allergy and Clinical Immunology.

Celiac Rash in Kids

Dermatitis herpetiformis (DH) is a chronic, intensely itchy and blistering skin manifestation of celiac disease. For some, DH may be the only sign of celiac disease. DH was once thought to mainly affect adults but a new study suggests it’s common in children, as well. Researchers from the University of Florence in Italy looked back at all 159 patients diagnosed with DH at their clinic between 1995 and 2012. To their surprise, a third were under the age of 20.

The team’s other findings were consistent with what’s known about DH—it affects more men than women and there’s intestinal as well as skin involvement. Among the 159 patients in the study, there was a preponderance of males and all of those who underwent intestinal biopsy had changes in the gut consistent with biopsy-proven celiac disease.

Findings were published in April in the Italian journal, Giornale Italiano di Dermatologia e Venereologia.

Rotavirus and Celiac Disease

Repeated infections with rotavirus, a nasty stomach bug, have been linked to a higher risk of developing celiac disease in genetically predisposed people. Now a study led by researchers from the University of Verona in Italy supports this finding. They discovered anti-rotavirus antibodies were present in 81 percent of children with celiac disease and type-1 diabetes compared to just 27 percent of children with type-1 diabetes alone. Further, the anti-rotavirus antibodies were present before the development of celiac-specific antibodies in most cases. Anti-rotavirus antibodies can modulate genes involved in inflammation and alteration of the intestinal barrier, researchers explain. They demonstrated this capability as part of their investigation.

Rotavirus is a very common contagious infection in infants and young children, causing severe diarrhea and vomiting. Since 2006, an oral vaccination has been available in the United States. Although the new research didn’t address whether vaccination could potentially offer protection from celiac disease, studies have shown that vaccination is up to 95 percent effective at preventing severe rotavirus disease.

The work was published in April in Immunological Research.

Celiac, Food Allergies Rising

The incidence of celiac disease in the United States has increased over the past decade, according to Mayo Clinic researchers. When they tracked all new celiac diagnoses in Olmsted County, Minnesota, they found the incidence rose from 11.1 cases per 100,000 person-years in 2000 to 17.3 per 100,000 person-years in 2010. There was a peak in diagnoses in 2004 (about 20 cases per 100,000 person-years) followed by a plateauing trend. (Person-years is a way of reporting incidence.)

Rates were highest among women and older adults—the incidence of celiac increased 6.5 percent with each decade of life. Although heightened awareness and better detection may account for some of the rise, researchers say it probably doesn’t explain all of the new cases. Something in the environment may be the blame, they say, although researchers didn’t speculate what that might be.

The study was published in March in the American Journal of Gastroenterology.

In separate research, a new Centers for Disease Control and Prevention survey has confirmed that the rate of food and skin allergies among children under 18 increased over the last decade, too. The overall rate of food allergies went up from 3.4 percent in 1997 to 5.1 percent in 2011. Skin allergies (such as eczema) increased from 7.4 percent to 12.5 percent in the same time period. Possible explanations for the uptick were not explored in the new report, which can be accessed at cdc.gov.

Know Your Gluten

At the medical meeting known as Digestive Diseases Week held in May, data from dozens of studies on celiac disease and gluten sensitivity were presented. One, led by a Canadian team at the University of Manitoba, looked at gluten-free food knowledge among those with celiac disease and/or dermatitis herpetiformis (DH).

Researchers developed a short survey where respondents categorized 16 foods as “allowed,” “foods to question,” and foods “not allowed.” Amazingly, none of the 179 respondents—most of whom reported strict dietary adherence—was able to correctly identify the gluten-free status of all 16 foods. On average, they restricted one or two of the six “allowed” foods (i.e., modified corn starch and glutinous rice) and three of the eight “foods to question.” Spelt, a wheat product, was recognized as a gluten-containing grain by just 77 percent of respondents.

Researchers concluded that ongoing gluten consumption may be common, even among people who believe they’re doing a good job adhering to a gluten-free diet.

Test for Gluten Sensitivity?

In another study presented at Digestive Diseases Week, researchers from the University of Rome described work they’ve done toward developing a novel test for non-celiac gluten sensitivity: the oral gluten patch test. At present, there’s not a test for non-celiac gluten sensitivity; diagnosis is made after excluding other possibilities like celiac disease and wheat allergy.

The new oral gluten patch test is based on the theory that the mouth, specifically the oral mucosa, is a possible site where adverse food effects can be seen. Previous research has shown that signs of immune activity can be found in the oral mucosa of celiac patients.

To test this in gluten sensitivity, researchers applied the gluten patch (a paper disk containing 1.2 milligrams of gluten) inside the upper lips of 20 gluten-sensitive individuals. (All participants tested negative for both celiac disease and food allergy.) Two hours later, the patch was removed and 16 of 20 participants—80 percent—experienced swelling, wheals and/or blistering at the application site. Half of the subjects also experienced bloating and 11 percent experienced diarrhea within 24 hours after taking the test.

Researchers say their study “documents the presence of local inflammatory lesions triggered by gluten in gluten-sensitive patients.” The same gluten-related inflammation seen in the oral mucosa could also be occurring in the intestinal mucosa, causing gastrointestinal complaints such as bloating and diarrhea, they add.

More research is needed to determine if the patch is a reliable way to test for non-celiac gluten sensitivity.

Self-Treating with the Gluten-Free Diet

More and more these days, people without a diagnosis of celiac disease are adopting the gluten-free diet to treat health complaints that range from gastrointestinal issues to headaches. According to a new study from the Mayo Clinic, celiac disease is relatively rare among these individuals. Just 2 percent of the so-called “self-treaters” whom the researchers studied actually had intestinal biopsy results consistent with celiac disease. (Only those participants still eating gluten at the time of their biopsies were included in this part of the analysis, meaning any celiac-related damage would likely be apparent, if present.) Additionally, a sizeable number (41 percent) lacked the genes associated with celiac disease, DQ2 and DQ8.

When researchers compared the symptoms of all 139 self-treaters to 443 biopsy-confirmed celiacs, diarrhea, bloating, cramping, itchy skin and headache were more frequent in the self-treating group. Anemia and malaise (generally feeling unwell) were reported more often in those with celiac disease. However, in both groups over 90 percent reported a benefit from the gluten-free diet. Altogether, the data supports the existence of non-celiac gluten sensitivity and the fact that this condition may play a role in those self-treating with the gluten-free diet, say researchers.

The study was published ahead-of-print in April in the Journal of Clinical Gastroenterology.

Note: Experts strongly recommend that people be screened for celiac disease before starting a gluten-free diet.

Antacids and Food Allergy

Researchers from Emory University School of Medicine in Atlanta have found a link between antacid use and food allergy. In their study, children who had taken antacid medications had nearly double the rate of food allergy compared to those who had never taken the medication (57 percent versus 32 percent, respectively). Antibodies to peanut (IgE) were also significantly higher in those who had taken the acid neutralizing medications. This isn’t the first study to call attention to a potential increased risk of food allergy with antacid use. Antacids may hinder the breakdown of food proteins, leaving behind food proteins that are too large and capable of inducing an immune response. Importantly, the study wasn’t designed to show antacids cause food allergy, only that there’s an association. The parents of some 104 children with atopic disorders (such as eczema, asthma, hay fever and food allergy) provided data on antacid use and food allergy for this research.

The study was published in the May/June issue of Allergy and Asthma Proceedings.

Senior medical correspondent Christine Boyd lives in Baltimore.

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