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Jun/Jul 2011 Issue
Research Roundup: Celiac, Heart Health, Asthma & Diet Therapy And More!
The latest medical news for people with allergies and food sensitivities
Celiac and Heart Health
Many people with celiac disease have been exposed to long-term inflammation in the gut. Chronic inflammation is a major risk factor for ischemic heart disease (IHD), the leading cause of death in the United States, and may help explain why researchers from the Karolinska Institute and Orebro University Hospital in Sweden recently found a 19 percent increased risk of IHD in individuals with biopsy-proven celiac disease. The highest risk of IHD was observed in the first year after diagnosis, which researchers think may be due to the presence of intense inflammation (and accompanying gastrointestinal symptoms) that prompted the patient to get tested for celiac disease.
Data on celiac diagnoses, going back to 1969, and the incidence of IHD was obtained through Swedish medical registers. The study included more than 40,000 patients with celiac disease, of which approximately 16,000 didn’t fit the traditional diagnostic criteria—positive blood tests and biopsy abnormalities, such as inflammation and villous atrophy. Having “latent” celiac disease, characterized by positive blood tests but normal biopsy findings, wasn’t associated with IHD; however, intestinal inflammation alone resulted in a 28 percent increased risk.
“The findings underscore the importance of using a biopsy to diagnose celiac disease,” says lead investigator Jonas Ludvigsson, MD, PhD. Biopsy-proven celiacs may need to pay more attention to well-established IHD risk factors, such as high blood pressure, cholesterol and BMI.
The study also provides further rationale for compliance with the gluten-free diet. Poor dietary adherence is associated with persistent inflammation, which may account for much of the increased risk of IHD in those with celiac disease, says Ludvigsson. The work was published in Circulation.
Celiac and Asthma Linked
In separate research out of the Karolinska Institute and Orebro University Hospital in Sweden, researchers found those with celiac disease were 60 percent more likely to develop asthma, with an increased risk remaining five years after diagnosis. Researchers compared rates of asthma diagnoses in nearly 30,000 biopsy-proven celiacs and 140,000 people without celiac disease. The study was the first large-scale investigation into the two conditions.
The link between celiac disease and asthma may be related to malnutrition, specifically vitamin D deficiency, say researchers. It’s estimated 60 to 70 percent of celiacs have low levels of vitamin D, often remaining low several years after starting the gluten-free diet, which may help explain the risk post-diagnosis.
Vitamin D has recently been the subject of several studies on asthma and allergies because it’s thought to have beneficial anti-inflammatory effects in the body. However, there may be other explanations for increased asthma risk in celiacs, such as a shared genetic predisposition for both conditions, since scientists also found having asthma increased the likelihood of a later celiac diagnosis.
Researchers underscore their work doesn’t show one disease causes another. More research is needed, they say. The study was published in the Journal of Allergy and Clinical Immunology.
Diet Therapy for ADHD
Parents have long suspected that food sensitivities play a role in triggering ADHD symptoms. Now a study conducted at the ADHD Research Centre in Eindhoven, Netherlands, strengthens the case.
In work published in Lancet, researchers recruited 100 children with ADHD, ages 4 to 8. Participants were randomly assigned to a restricted, “hypoallergenic” elimination diet consisting primarily of rice, meat, vegetables, pears and water, or to a regular balanced diet. After five weeks, 64 percent of children on the restricted diet had a clinical improvement of at least 40 percent on ADHD scores. No improvement was observed in children on the regular diet.
Children who responded to the restricted diet then proceeded to the second phase of research, where, based on individual blood tests measured at the start of the study, three high-IgG and three low- IgG foods were added, alternately, to the diet for two weeks. Researchers wondered if levels of IgG, an antibody in the blood, could help pinpoint specific food sensitivities (i.e., high-IgG foods would exacerbate symptoms). Results revealed that IgG blood tests didn’t predict which foods might have an adverse effect on behavior: 63 percent of children experienced a relapse of ADHD behavior, regardless of whether they were eating high- or low- IgG foods.
Noting that behavioral improvements may be attributed, at least in part, to increased attention paid to children in the restricted-diet group, researchers concluded that the elimination diet is a “valuable instrument to assess whether ADHD is induced by food.” They suggested that dietary intervention be considered in all children with ADHD.
Antibiotics Raise Risks
Researchers from Yale University’s School of Public Health studied over 1,400 newborns from birth through age 6, finding that children exposed to antibiotics before 6 months of age were up to 52 percent more likely to develop asthma by age 6 than those not treated with antibiotics. The risk increased when more courses of antibiotics were used.
A link between antibiotic use and asthma has been previously reported but many questioned it, pointing out that children treated with antibiotics for respiratory tract infections may have had unrecognized asthma. Symptoms can appear similar. However, Yale researchers found an increased risk of asthma in children who didn’t experience respiratory tract infections in the first year of life, in those whose asthma wasn’t diagnosed until after age 3, and in those without family histories of the condition.
Positive allergy (IgE) blood tests and skin prick tests to egg and other food or environmental allergens were also observed more often in children exposed to antibiotics before 6 months of age. However, previous studies haven’t linked antibiotics and IgE levels in children and more research is needed.
Antibiotics used early in life may alter intestinal microflora, bacteria thought be important for developing a healthy immune system with resistance to allergic sensitization. Data on the specific type of antibiotics (e.g., broad versus narrow spectrum) weren’t collected.
The findings, published in the American Journal of Epidemiology, suggest another reason to avoid unnecessary antibiotic use.
Medical writer Christine Boyd lives in Baltimore.