A recent article in the New York Times brought my attention to a study that is currently in process about adult-onset food allergies. I have seen many patients who develop allergic symptoms later in life. When I suggest that the symptoms may be related to a food, people often respond with “but I have eaten this all my life.”
I am glad to see that researchers are looking into the question of how and why food allergies develop because I often see patients with severe and life-altering symptoms from immune reactions to foods. There is a significant difference between food allergies and food intolerances and both can develop in adulthood.
Food Allergy vs. Food Intolerance
A food allergy produces hives, mouth itching, throat swelling or anaphylaxis (allergic emergency) within two hours after ingesting a food. Typically, these reactions can occur with very mild exposures such as contact with a surface that someone touched after eating that food or kissing someone who has eaten that food. These reactions can become life-threatening quickly and often require that the allergic person carry an epi-pen to prevent airway closure and anaphylaxis.
A food intolerance can produce symptoms including fatigue, brain fog, constipation, diarrhea, weight gain, congestion or headaches. Food intolerances are more difficult to identify because they often become symptomatic eight to 24 hours after ingestion of the food that is causing the reaction. In order to identify food intolerances, I often lead my patients through elimination diets and/or do food intolerance blood testing which looks for antibodies to foods. This blood testing has helped me identify food intolerances that I would never have figured out through an elimination diet.
Food Allergies and Food Intolerances Can Develop at Any Age
The important thing that this study is bringing to light is that food allergies (and also food intolerances) can develop at any age and we do not really know why. Some triggers that the researchers are considering are viral infections and misidentification of proteins by the immune system due to similarities with environmental allergens or pathogens.
Other studies have focused on “leaky gut” or intestinal permeability which allows proteins to pass into the bloodstream in forms that the immune system does not recognize as food.
The immune system is a constantly changing mechanism for identifying pathogens. Immune cells are capable of “learning” to identify bacteria and viruses that they have never encountered before. This identification system is susceptible to errors and we can support the gastrointestinal tract and immune system in ways that may reduce the likelihood of those errors.
In my practice, I have seen food allergies and intolerances resolve with immune modulating therapies like probiotics and fish oil or nutritional support for strengthening tight junctions in the digestive tract like glutamine and a low-sugar diet.