Having a food sensitivity is life-altering. Avoiding a particular food or food component can be challenging and avoidance is currently our primary treatment option for this kind of condition. Given that one fifth of the population will be affected by food sensitivity in their lifetime, discovering alternatives to help manage them is critical.

Food sensitivities have been increasing at a rate that outpaces genetic changes—and the gut microbiota has been identified as a contributing factor. A new Nature review led by Elena Verdú of McMaster University in Canada highlights current research on how changes in the gut microbiota alter interactions with the immune system to drive the development of food sensitivities.

First and foremost, it is important to understand the difference between a food intolerance and food sensitivity, as they are often subject to confusion. Food intolerances do not involve the immune system and are not life-threatening, whereas food sensitivities involve activation of the immune system and have serious health implications, which can even include death. Our infographic allows learning more about intolerances and sensitivities.

The development of a food sensitivity changes how the immune system responds to a food component, causing an inappropriate immune reaction. We rely on appropriate immune reactions for normal immune responses – meaning our immune system can identify food components as safe and not react to them. In individuals with food sensitivities, this loss of tolerance means their immune system inappropriately identifies food components as harmful substances and reacts. Researchers have identified alterations in the gut microbiota, driving this shift in immune activation. These alterations occur due to genetics, environment, the role of the gut microbiota in maintaining a normal immune system and, lastly, how the gut microbiota interacts with food components.

Genetics and Environment
Alterations in the gut microbiota have been identified as one way in which those who are genetically predisposed may develop an autoimmune condition. Bacterial and viral infections, or depletion of protective bacterial strains in the gut, have been implicated in increasing susceptibility to a loss of tolerance. Bacterial and viral infections have the potential to suppress appropriate immune responses by triggering inflammation and altering gut permeability, thus driving the development of a food sensitivity.

While genetics appear to play a role, so too do environmental factors that influence the gut microbiota, especially during vulnerable or developmental periods, such as early life. Associations have been observed between a risk of food sensitivities and infant feeding, mode of delivery and antibiotic intake, all of which influence the gut microbiota and subsequent immune function.

How the Gut Microbiota Maintains Immune Function
Diet appears to be one way to maintain normal immune function in the gut. In animal models, studies have shown that diets higher in fiber, fermented foods, and certain fats can improve immune tolerance and protect against allergies.

To better understand how the gut microbiota maintains immune function, researchers have turned to animal models, finding that total number and types of bacteria can account for changes in immune function. Certain bacteria can positively regulate the immune system, and have been found to help maintain the gut barrier and mucosal layer, protecting against loss of tolerance.

With the important role bacteria play in maintaining the immune system in mind, researchers have questioned how probiotics can influence food sensitivity development and management. One study found that a combination of Bifidobacterium longum BB536 and Bifidobacterium breve M16-V taken by pregnant women reduced their infants risk of atopic dermatitis after birth. Another study performed in animals found a probiotic combination of several strains of Bifidobacterium and Lactobacillus reduced the severity of allergic reaction by modulating the immune system. This provides valuable insight to how probiotics may have applications in the prevention and treatment of food sensitivities – however, more human studies are needed before we can use probiotics to help manage food sensitivities.

How the Gut Microbiota Interacts with Food Components
The gut microbiota interacts with food components in a way that may affect the severity of food sensitivity. In celiac disease, for instance, it has been discovered that certain bacteria in the gut break down the gluten protein, and can either increase or decrease its toxicity.  Certain strains of Lactobacillus found in healthy individuals can degrade gluten into small molecules called peptides in order to decrease the immune reaction. This provides hope that increasing or decreasing certain types of bacteria in the gut may reduce the toxicity gluten has in those with celiac disease.

Dr. Verdú’s review provides a comprehensive overview of how the gut microbiota has been implicated in immune function and the development of food sensitivities. It highlights the growing body of literature around the importance of gut health in reducing allergy risk, and explores potential gut microbiota-specific targets to reduce allergy risk or severity. In the meantime, maintaining a healthy gut microbiota and reducing the risk of bacterial and viral infections appears to be beneficial to reducing the risk of developing food sensitivities. Simple ways to keep your gut microbiota healthy include maintaining a healthy diet with enough vegetables, fruit, and fermented foods! My favorite tips include eating fermented or probiotic foods, like yogurt or kefir every day, and aiming for 2 cups of vegetables at lunch and supper each day!

Reference:

  1. Caminero, A., Meisel, M., Jabri, B., & Verdu, E. F. (2018). Mechanisms by which gut microorganisms influence food sensitivities. Nature Reviews Gastroenterology & Hepatology. doi:10.1038/s41575-018-0064-z
Andrea Hardy
Andrea Hardy
Registered Dietitian, Andrea Hardy from Calgary, Canada specializes in gastrointestinal disorders and the gut microbiome. She is recognized as Canada’s gut health dietitian – educating health care professionals and the public on the pivotal role nutrition plays in gut health. You can find her at Ignite Nutrition, or on Twitter (@AndreaHardyRD).