Research Roundup: Gluten and Schizophrenia, College and Special Diets, and More!
City Kids Have Food Allergies
Researchers from Northwestern University Feinberg School of Medicine and Children’s Memorial Hospital in Chicago recently surveyed the parents of more than 38,000 U.S. children about the presence of food allergy, mapping the data by geographic location. They found kids living in urban areas have a much higher prevalence of food allergies compared to children in rural areas (9.8 versus 6.2 percent, respectively). In particular, kids in big cities had twice the odds of having peanut and shellfish allergy compared to their rural counterparts. Of note, severity of food allergy didn’t follow the same trend; reports of life-threatening reactions to food were similar across geographic locations.
The research suggests that environment has an impact on developing food allergies. In a press statement, lead author Ruchi Gupta, MD, said “a better understanding of environmental factors will help us with prevention efforts.” The study was published in July in Clinical Pediatrics.
At diagnosis, celiacs have a lower body mass index (BMI) than the general population but BMI increases on the gluten-free diet, particularly in those who closely adhere to the diet, say researchers from Beth Israel Deaconess Medical Center in Boston. The team looked back at data on weight and dietary compliance collected from a large group of celiac patients over the course of several years.
On the gluten-free diet, especially among those compliant with it, average BMI of the group rose from 24 to 24.6. (Normal BMI ranges from 18.5 to 24.9; 25 and up is considered overweight.) Although BMI changes are often expected after diagnosis—the result of a new diet and better absorption of calories—BMI increases in the study were directly correlated with the duration of follow-up, suggesting ongoing weight gain. Researchers say maintenance of a healthy weight should be an integral part of nutritional counseling for patients with celiac disease.
The study was published in March in Alimentary Pharmacology and Therapeutics.
Gluten and Schizophrenia
Evidence that gluten may play a role in some cases of schizophrenia is mounting. Last year, researchers published data showing persons with schizophrenia had higher than expected levels of antibodies related to celiac disease and gluten sensitivity. Now a study published in April in Schizophrenia Bulletin has found a higher rate of antibodies to tissue transglutaminase 6 (tTG6) in patients with schizophrenia compared to control subjects. Tissue transglutaminase 6 antibodies are primarily expressed in the brain and have been linked with gluten ataxia, an autoimmune condition that causes problems with balance and coordination.
Much more work is needed but researchers say tTG6 antibodies may help identify schizophrenic patients who could potentially benefit from the gluten-free diet. A team from Johns Hopkins University School of Medicine, the Maryland Psychiatric Research Center and the University of Maryland Center for Celiac Research collaborated on the study.
In related research from the Karolinska Institute in Sweden and Johns Hopkins University School of Medicine, investigators found babies born to mothers with high levels of anti-gliadin antibodies had nearly twice the risk for developing schizophrenia and other psychiatric disorders later in life. The researchers used stored neonatal blood samples from Swedes born between 1975 and 1985 to measure levels of both anti-gliadin and anti-casein antibodies. (A higher rate of schizophrenia was not linked to casein, a milk protein.)
Because a mother’s antibodies transfer to the fetus during pregnancy, high levels in the newborn point to high levels in the mom. Anti-gliadin antibodies indicate an immune response to gliadin (a component of gluten) and are positive in many patients with celiac disease and up to 50 percent of those with gluten sensitivity.
Lead author Hakan Karlsson, PhD, said in a press release, “…factors during the pregnancy and immediately after birth can be involved in the pre-programming of our adult health. However, this does not mean that sensitivity to certain foods invariably will cause schizophrenia….”
According to the National Institute on Mental Health, experts think schizophrenia is caused by many factors, including genetics. Karlsson says his team is planning follow-up studies “to clarify how gluten or sensitivity to it increases schizophrenia risk and whether it does so only in those genetically predisposed.”
The study was published in June in the American Journal of Psychiatry.
College and Special Diets
An online survey of 395 food-allergic students from Iowa State University and the University of Northern Iowa reveals that students don’t feel their food allergies are particularly well accommodated. Participants reported allergies to milk, peanuts, tree nuts or other foods. Almost half said they’d experienced an allergic reaction while enrolled in school. (Just over half also admitted to occasionally eating foods they’re allergic to; such risk-taking behavior has been previously described in college students.) The students asked for more allergy-friendly options and better food labeling on campus. They also recommended that more information be given about food allergy accommodations during orientation. Led by Iowa State University (ISU) assistant professor Lakshman Rajagopal, PhD, results were presented in July at the annual meeting of the International Association for Food Protection (IAFP) in Providence, Rhode Island.
In a separate study published in the Journal of Pediatric Gastroenterology and Nutrition, celiac students from six U.S. colleges reported that navigating the gluten-free diet was difficult at school, rating cross contamination as one of the biggest challenges. All students said that dining services claimed to accommodate the gluten-free diet, yet 60 percent said they were ill on a weekly basis due to dining hall cross contamination. Some 30 percent said symptoms interfered with class attendance.
Accidental Exposure Is Common
Preschool-aged children allergic to milk and eggs frequently experience allergic reactions due to accidental exposure, and severe reactions are seldom treated with epinephrine, according to a new study in Pediatrics.
Researchers tracked a group of 500 tots with milk and egg allergy in five U.S. cities over an average of three years. During that time, 72 percent experienced at least one allergic reaction, most often caused by a lapse in vigilance (i.e., an unsupervised child ate the food or the caregiver failed to check ingredients). Misreading a label and cross-contamination were less common reasons for accidental exposure.
Of those reactions that were severe, just 30 percent were treated with epinephrine, often because the severity of the reaction wasn’t recognized. In addition to stressing vigilance with food-allergic tots, researchers emphasize the need for education about the symptoms that warrant epinephrine treatment. These can include difficulty breathing, dizziness or loss of consciousness.
Researchers from National Jewish Health in Denver, University of Arkansas, Johns Hopkins School of Medicine, Duke University Medial Center and Mount Sinai School of Medicine participated in the study.
EmA Predicts Celiac
Researchers from Tampere University Hospital in Finland recently looked at the association between endomysial antibody (EmA) levels and a subsequent diagnosis of celiac disease in 405 children and adults. All of the participants were EmA positive, having been tested because of a family history of celiac disease or gastrointestinal symptoms. A subset of participants had non-intestinal (atypical) celiac symptoms.
In total, 79 percent of participants with low EmA levels and 94 percent with high levels were found by biopsy to have small-bowel villous atrophy and were diagnosed with celiac disease. Interestingly, almost all of those EmA-positive patients who initially had normal villi either went on to develop villous atrophy (while on a gluten-containing diet) or responded positively to the gluten-free diet.
Regardless of initial levels or symptoms, a positive EmA result is a very strong predictor of a subsequent celiac diagnosis, the researchers write. The study was published in May in World Journal of Gastroenterology.
Shorter Gluten Challenge
A gluten challenge is needed to test for celiac disease when a patient is already on the gluten-free diet. That’s because blood and biopsy testing isn’t accurate unless a person has been eating gluten. However, a new study has found the traditional 8-week gluten challenge is longer than necessary in many cases.
Researchers from the Celiac Center at Beth Israel Deaconess Medical Center in Boston randomly assigned 20 adults with biopsy-proven celiac disease to a 14-day challenge with 3 or 7.5 grams of gluten per day. After two weeks—and with just 3 grams of gluten per day (equivalent to 1½ slices of wheat bread)—over 75 percent of adults met the criteria for celiac disease.
A lengthy gluten challenge is often very difficult for patients. The new finding may make the challenge more tolerable, say researchers. Additionally, investigational drugs for celiac disease may be able to be tested in shorter, two-week trials.