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‘Do You Have a Food Sensitivity?’ and Other Questions Answered

A collection of milk and cheese against a white background

Fad diets tell us removing just one food from our daily lives will make us feel healthier. Manufacturers of at-home genetic tests say they may identify a gene that makes us susceptible to gastrointestinal (GI) conditions. The hypochondriac in us may take pause and begin to wonder if we should make our diets smaller and more precise. It’s easy to think: Do I have a food sensitivity?

“It might seem like you could have an unknown food sensitivity, but in general, most people are aware if certain foods actually bother them,” said Nitin Ahuja, MD, an assistant professor of Gastroenterology and the co-director of the Program in Neurogastroenterology and Motility at the Perelman School of Medicine at the University of Pennsylvania. “More and more, patients come in and are interested in formal testing, but it’s often not necessary.”

In fact, other than a breath test for lactose intolerance where a patient’s breath is tested for high levels of hydrogen caused by the inability to digest lactose, a sugar found in milk, most food sensitivities cannot be identified from simple clinical tests or even endoscopies.

“If a patient has severe weight loss, stomach pain, or constipation or diarrhea, especially if these symptoms are new and appeared all of the sudden, there could be something more serious at play, and I would encourage people experiencing that to see a doctor right away,” said Ahuja. “Tests for other, more serious conditions would be warranted.” 

Food Sensitivities are Not Allergies

Food sensitivities and intolerances are not food allergies, said Ahuja. While both are some weird or seemingly inappropriate reactions to what we eat, allergies are a response in the body involving the immune system and usually a protein. A specific protein of the food is perceived by the body to be a threat, and the immune system creates its own proteins to fight the mistaken threat. While stomach pain, vomiting, and diarrhea can be symptoms of a food allergy, according to the American Academy of Allergy, Asthma & Immunology, so can hives, swelling, and even trouble breathing. The effects of a food allergy are instantaneous.

Food intolerances and sensitivities occur simply when the body does not properly digest a food. That means the GI tract lacks an enzyme it needs to break down the food or a chemical in the food, as is the case for those with lactose intolerance where there is lack of a lactose-related enzyme, said Ahuja.

Food Sensitivities are Not Sudden Onset

While you can develop food sensitivities or bathroom irregularity as you age, after pregnancy, or even from conditions like inflammatory bowel disease, it’s more common for food sensitivities to pop up gradually over time and be noticed more slowly, said Erin Toto, MD, a clinical assistant professor of Gastroenterology at Penn. “For example, you do not wake up one day suddenly unable to drink milk without stomach pain,” she said. Food insensitivities can also develop or increase in severity as we age since our bodies generally make fewer digestive enzymes over time.

Food Sensitivities are Not Dangerous Long-Term

The most dangerous part of a food sensitivity is that due to avoiding certain foods, you might not eat enough calories to maintain a healthy weight or not ingest enough of a specific vitamin or mineral. Other than experiencing the symptoms of eating something that bothers your stomach, ingesting a food you are sensitive to does not cause any permanent harm.

This difference is what separates the autoimmune condition celiac disease from just a gluten sensitivity, as one example. When someone with celiac disease eats gluten, their body damages the lining of the small intestine, said Toto. A simple gluten sensitivity just causes gas and the traditional sensitivity GI symptoms.

“Eating foods one is sensitive to is generally safe,” said Ahuja. “You have to know yourself and know what symptoms you’re willing to put up with. It’s also likely that you can tolerate a certain amount of the food you are sensitive to or a certain version.”

In the case of mild lactose intolerance, for example, a scoop of ice cream may be easy to handle while a glass of milk could derail your day, Ahuja said. Everyone is different and can figure out what their body can tolerate.

Food Sensitivity is Not Rare

Food sensitivities are anything but rare. In fact, estimates put the prevalence of some degree of lactose intolerance around the world at over 50 percent, said Ahuja. Other patterned sensitivities can include histamines, a naturally-occurring chemical in foods from chocolate to bananas, gluten found in grains, and sugars.

What to Do if You Suspect a Food Sensitivity or Allergy

Those with brand new symptoms should seek medical care, said Toto. “A simple history and some bloodwork is usually sufficient to screen for anything serious,” she said.

If you suspect you have a new food allergy, you should also see to your doctor and potentially seek care from an allergy specialist who could recommend medication or allergy shots.

But if you simply suspect food intolerances, you can start by journaling. Write what you eat, when, and how you feel afterward. You may start to see patterns, said Ahuja. A clinician can also help you safely eliminate foods to help determine what might be causing symptoms.

Ultimately, when you identify that you are sensitive to certain foods, you can try to select what you eat to avoid them whenever possible.

Scientists are continuing to analyze a variety of specific diets, like the Mediterranean diet, as a potential tactic for those with food intolerances. FODMAPs (femermentable oligosaccharides, disaccharides, monosaccharides, and polyols) have been the subject of research directed toward the treatment of irritable bowel syndrome (IBS) over the last several years. According to a 2021 research review in Clinical Nutrition, largely limiting foods high in these carbohydrates, foods including dairy, wheat, and specific fruits, vegetables, and even some marinated or processed meats, was shown to alleviate IBS symptoms, increase stool consistency, decrease stool frequency, and lead to better satisfaction with bowel habits compared to those who didn’t try this diet or who followed it to a lesser extent.

In the future, there may also be new tools people can use to know just what is in their food. One such product exists for detecting gluten in foods or drinks. Future technology like this may allow people to more easily avoid GI triggers.

Research is ongoing around the world to find other ways to deal with food intolerances other than avoidance. For example, some are looking into the effectiveness of various enzyme supplements for those with food intolerance caused by a lack of enzymes. A common example is lactase (which goes by several brand names like Lactaid). Available research is small and inconclusive although some patients report it alleviates symptoms, said Ahuja. Whether it works or not for a specific individual may be dependent on other factors that research may soon uncover.

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