Food allergies—an overreaction of the immune system to specific proteins found in food—are a growing food safety and public health concern that, in addition to health, affect school and work attendance, family economics, and social interactions. For example, results from a study published in 2013 show that children are bullied for their allergies, causing distress in both the bullied children and their parents. In addition, children with food allergies are often distressed and anxious “because they won’t touch a doorknob or use a bathroom, because they fear inadvertent exposure to their allergen.”
Food allergy symptoms such as digestive problems, hives or swollen airways can appear even when coming in contact with very small amounts of the specific food causing allergy. In few instances, food allergies may result in severe symptoms or even anaphylaxis, a life-threatening reaction. Many food allergies are first diagnosed in young children. However, they may also occur in older children and adults, and should not be confused with food intolerance, a less serious condition that is not immune system-related. “Food allergies are real and can be life-threatening. It would be folly to dismiss them. But many people think they have them when they actually don’t.” Indeed, people with food allergies have far less chance of dying from anaphylaxis than from an accident.
So, what causes food allergies, and what can be done to control them? Results from a recent study carried out in a mouse model provide information that will be helpful to answer these questions. The study (Dietary fiber and bacterial SCFA enhance oral tolerance and protect against food allergy through diverse cellular pathways} shows that food allergies in mice can be linked to what their gut bacteria—or microbiome—are being fed. Gut bacteria break down dietary fiber into their byproducts—primarily short-chain fatty acids. Mice that received a diet with average calories, sugar, and fiber content from birth had more severe peanut allergies than those that received a high-fiber diet. The gut bacteria of mice fed the high-fiber diet released specific fatty acids in response to fiber intake. The researchers found that these fatty acids support the immune system by binding specific receptors on T regulatory cells. The binding of fatty acids to these receptors triggers the T regulatory cells to initiate a cascade of events, which in turn regulates the inflammatory response in the gut.
Laurence Macia, one of the study co-authors, said in a press release: “We felt that the increased incidence of food allergies in the past ten years had to relate back to our diet and our own microbiome rather than a lack of exposure to environmental microbes–the so-called Hygiene Hypothesis. Most researchers in this field look at excess fat as the problem—we were one of the first looking specifically at fiber deficiency in the gut.”
Charles Mackay, another study co-author, added: “It’s likely that compared to our ancestors, we’re eating unbelievable amounts of fat and sugar, and just not enough fiber. And these findings may be telling us that we need that high-fiber intake, not just to prevent food allergy, but possibly other inflammatory conditions as well.”