Food reactions can happen to anybody—from children to adults. Food allergies , a life-threatening immune response, affects about 32 million Americans, according to Food Allergy Research and Education (FARE). Add in food sensitivities and intolerances and even more people suffer from uncomfortable symptoms that come from food.
Commonly, food allergies show up in childhood, but allergies, sensitivities, and intolerances can also pop up later in life. This is typically due to a weakening of the intestinal lining that leads to an increase in space between cells in the intestinal tract, called leaky gut . “Those spaces allow for the passage of food particles, bacteria, viruses, and all that triggers inflammation ,” says Svetlana Stivi, MD , a Los Angeles-based doctor at Parsley Health. Often, as we age, we can’t digest the same portion sizes or the same foods without feeling some digestive discomfort.
While food allergies often get diagnosed via blood tests and/or skin prick tests, pinpointing your personal food sensitivities or intolerances can take some more time. One reason why: It requires work from the patient, usually in the form of a food diary (that includes how you feel after eating) to uncover what your body can and cannot tolerate, Dr. Stivi says. Plus, many people have an emotional attachment to food, she says. While pizza or ice cream might bring you lots of joy, they might also come with an upset stomach—sometimes it’s difficult to pick whether you push through the discomfort or skip the meal.
If you suspect you have a food sensitivity or intolerance, here’s what you need to know to figure out your body’s reaction to your diet.
The biggest difference between food allergies and intolerances or sensitivities is that the latter two aren’t life threatening, Dr. Stivi explains. If you have a food sensitivity or allergy, your immune system identifies that food as an invader, Dr. Stivi explains. Your body thinks it needs to protect you and produces antibodies to do so. While the immune system plays a role in both food sensitivities and food allergies, the food reaction will recruit different immune cells and then lead to a different immune response and resulting symptoms. For allergies, IgE antibodies send messages to other immune system cells that cause an allergic reaction or anaphylaxis, which can cause you to go into shock and can be fatal. With food sensitivities, the body produces igG antibodies, which can lead to more subtle and longer lasting effects.
Food intolerances, on the other hand, mainly affect the digestive system (though symptoms can be wide-ranging). Intolerances often lead to micro-inflammation in the intestinal tissue, which can also affect other systems of the body and may explain why an intolerance shows up as something seemingly unrelated, like nasal congestion.
Another big distinguisher: Intolerances and sensitivities are often dose-related, meaning people can tolerate a small amount of the food without showing symptoms. While some people might tolerate some dairy , for example, eating a large amount of high-lactose dairy may just sit in the gut for someone who doesn’t have enough digestive enzymes to break it down (aka those with lactose intolerance). This leads to issues like bloating and gas .
Sometimes you just need less of that food or to eat it less frequently, depending on how your body reacts to it. “Rest, sleep, and stress management can all come into play in how our gut expresses food sensitivities too,” Dr. Stivi says.
Also, while food intolerance and sensitivity are similar, you might have more severe symptoms if you’re intolerant to a food. Intolerances are usually more specific, too, while sensitivities can often pertain to a wide range of foods, Dr. Stivi says. Lactose intolerance, for example, is when you have an inability to process and digest the milk sugar called lactose, while a dairy sensitivity is an immune response to one or more protein -based components of cow’s milk (such as whey or casein).
Those with food sensitivities might experience:
People who have a food intolerance might experience:
Those with food allergies have a range of symptoms, including:
Common causes of sensitivities and intolerances include:
Common causes of food allergies:
To help rule out a food sensitivity or intolerance or pinpoint the foods causing your symptoms, Parsley Health doctors often recommend doing an elimination diet . This requires eliminating certain foods and food groups for a few weeks and then slowly reintroducing them so you can test how your body reacts to those newly added foods. Your health coach will guide you through the elimination diet and help you identify any triggers.
Lab tests may also be used to reveal what foods might cause an immune response. However, food sensitivity tests can sometimes reveal 100 or 200 foods that could cause issues, particularly if you’re examining sensitivities rather than specific intolerances. This may happen for several reasons, one being that your body builds up a memory response from consuming a specific food many times, sort of like an immunization, Stivi says. So, while you’ll have more information on foods to pay attention to, figuring out exactly what to leave out and keep in your diet may still involve some trial and error to see what works best for your body, Dr. Stivi says, who mentions the elimination diet is still the best way to figure out your sensitivities.
Dr. Stivi also mentions the importance of checking for underlying conditions, like irritable bowel syndrome or inflammatory bowel disease when addressing food reactions, as the approach to testing and treatment will likely look different if you have these conditions. And not all digestive issues are necessarily food-related—factors like anxiety can also cause digestive issues, so treatment might go beyond diet.Finally, finding ways to support the gut and restore gut function can also be helpful for addressing digestive issues related to food. Parsley Health providers and health coaches work diligently with members to improve their gut health through nutrition, supplements , and more. “It takes patience, investigation, and good will,” Dr. Stivi says of reaching a plan that works for your body and helps control digestive issues. “But there is a solution.”
Mallory, a New York City-based freelance writer, has been covering health, fitness, and nutrition for more than a decade. Her work has appeared in publications like Women's Health, Men's Journal, Self, Runner's World, Health, and Shape, where she previously held a staff role. She also worked as an editor at Daily Burn and Family Circle magazine. Mallory, a certified personal trainer, also works with private fitness clients in Manhattan and at a strength studio in Brooklyn. Originally from Allentown, PA, she graduated from Syracuse University's S.I. Newhouse School of Public Communications.