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Research Roundup: April/May 2019

The latest medical news for people with allergies and food sensitivities for April & May 2019

Adults Have Food Allergies

The prevalence of food allergy in the adult population of the United States has been estimated at about 9 percent. Yet the true rate and severity of food allergies among U.S. adults is largely unknown. So a group of researchers, many associated with Northwestern University, decided to look into it.

They conducted a survey study of 40,443 U.S. adults and found that about 10.8 percent of participants had a food allergy at the time of the survey. (An additional 19 percent believed they had a food allergic.) Almost half of the food-allergic adults had at least one adult-onset food allergy and 38 percent reported at least one food allergy-related emergency department visit in their lifetime.

Among the food-allergic adults, 51 percent experienced a severe food allergy reaction, 45 percent were allergic to multiple foods and 48 percent developed food allergies as an adult. The most common allergies were shellfish, milk, peanut, tree nut and fin fish.

The data suggests that at least one in ten U.S. adults has a food allergy.

Food allergies are common and severe among U.S. adults, often starting in adulthood, the researchers said. “Overall, approximately half of all food-allergic adults developed at least one adult-onset allergy, suggesting that adult-onset allergy is common in the United States among adults of all ages, to a wide variety of allergens, and among adults with and without additional childhood-onset allergies.”

The study was published in JAMA Network Open.

Penicillin Allergy Is Often Misdiagnosed

Approximately 10 percent of Americans (about 32 million people) say they’re allergic to penicillin. Yet according to a recent report, most who report having a penicillin allergy aren’t actually allergic to it.

Penicillin is considered one of the safest and most effective family of antibiotics. People who mistakenly tell their doctors they’re allergic to it may be prescribed broad-spectrum antibiotics instead, unnecessarily increasing their risk of side effects, as well as antimicrobial resistance.

Most patients with a documented penicillin allergy were diagnosed as children, the authors reported. They explained that true IgE-mediated penicillin allergy wanes over time, with 80 percent of patients becoming tolerant of the drug after a decade of being told they’re allergic.

The report was published in the Journal of the American Medical Association.

Celiac & Pneumococcal Infection

Many case studies have linked celiac disease with pneumococcal infections but the increased risk for people with celiac disease to contracting pneumococcal infection is not well established. Recently, a team of researchers decided to conduct a systematic investigation into the matter.

Caused by streptococcus pneumoniae bacteria, pneumococcal infection can prompt a slew of different illnesses, from ear infections to meningitis. In 2014, The British Society of Gastroenterology updated its guidelines for celiac management to recommend vaccination against pneumococcal disease. The United States has no similar celiac guideline for this vaccination.

Researchers found that celiac disease is, in fact, associated with an increased risk of pneumococcal infection. Overall, the odds of people with celiac contracting a pneumococcal infection is about double that of those who don’t have the disease. Preventive pneumococcal vaccination should be considered for those with celiac disease, with special attention to those aged 15 to 64 years who have not received the vaccine, researchers said.

The study was published in The American Journal of Medicine.

Anemia & Celiac

Adults and children with classic celiac disease show the signs and symptoms of malabsorption, including iron-deficiency anemia. That’s why current celiac guidelines recommend screening patients with iron-deficiency anemia for celiac disease.

But the prevalence of biopsy-verified celiac disease in patients with iron-deficiency anemia varies. So a team of researchers performed a systematic review to see if they could determine that prevalence. They found that about 1 in 31 patients with iron-deficiency anemia has histologic evidence of celiac disease [as shown in microscopic tissue examination].

“This prevalence justifies the practice of testing patients with iron-deficiency anemia for celiac disease,” the researchers said.

The study was published in Gastroenterology.

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Saudis Are Highly Susceptible to Celiac

A recent screening of almost 8,000 school-age Saudi children revealed that the rate of celiac disease in the pediatric population in that country is about 1.5 percent. (The prevalence of celiac disease in the U.S population is about 1 percent.) Researchers wondered if this high prevalence could be due to an above-average presence of HLA-DQ2 and HLA-DQ8 (celiac-predisposing human leukocyte antigen proteins) in their population. So they conducted a cross-sectional study to find out.

They randomly selected 192 healthy school children whose blood tests showed no evidence of celiac disease (their screening results were all negative for tissue transglutaminase-IgA). In this group of kids, almost 53 percent carried the high-risk celiac-associated HLA-DQ molecules.

Calling the results “one of the highest frequencies of celiac-predisposing genotypes among healthy general populations worldwide,” the researchers stated that the findings could explain, at least partly, the high prevalence of celiac disease in the Saudi community.

The study was published in the Saudi Journal of Gastroenterology.

Low-Gluten Diet Impacts Gut Microbiome

A low-gluten diet is increasingly popular for people who don’t have celiac disease. So how does reducing gluten-rich foods (wheat, barley and rye) impact healthy adults?

Danish researchers recently compared the effects of a low-gluten diet with a high-gluten diet in a study of 60 middle-aged Danish adults with no known medical disorders. Participants on both diets ate foods of similar nutritional quality and dietary fiber. In the high-gluten diet, dietary fibers came mostly from wheat and rye. In the low-gluten diet, dietary fibers came primarily from vegetables, berries, oats and cereals other than wheat or rye. There was high compliance with both diets.

Researchers found that the two diets were associated with changes in 14 bacterial species in the gut. Participants on the low-gluten diet consistently showed decreased abundance of bifidobacteria and various interrelated species. Lower wheat consumption likely caused this reduction, researchers said. Healthy populations living traditional lifestyles have low fecal bifidobacteria compared with people in industrialized countries. The abundance of anti-inflammatory gut bifidobacteria in adults living a Western lifestyle may be a compen-satory mechanism for their high dietary intake of poorly digestible wheat peptides, the authors hypothesized.

While on a low-gluten diet, participants reported less bloating, increased well-being and small weight losses. These benefits may have come from the change in dietary fibers, rather than from the absence of gluten per se, the researchers said. It is important to note that most currently available gluten-free products are low in dietary fibers and other nutrients, which highlights the need for fresh or minimally processed fiber-rich gluten-free foods that are nutritionally dense.

Currently available scientific evidence does not support avoidance of gluten by healthy adults. However, researchers suggested that doctors might consider two months of observation on a low-gluten diet for healthy adults with persistent intestinal complaints after carefully excluding all known gastrointestinal disorders.

The study was published online in Nature Communications.