You can’t open a health magazine these days without reading story after story about gluten. (Yes, we’re guilty of catering to reader interest when it comes to the controversial grain protein.)
But while our collective gluten obsession has probably gone a little overboard, the science on gluten helps underscore the complexity of our digestive systems and how food-related gut issues emerge.
While there’s no question some people have an allergy to gluten, which is known as celiac disease, there’s a great deal of expert debate regarding the existence of “non-celiac gluten sensitivity”—a condition separate from celiac that’s linked with abdominal pain, headaches, fatigue, and other symptoms.
Throw in the concept of a food “intolerance,” and it’s hard to keep all the terminology straight—let alone the triggers.
“If you have a food allergy, that means your body makes an antibody reaction in response to a food,” says Princess Ogbogu, MD, an allergist and internal medicine expert at Ohio State University. “That antibody causes the body to release histamine, which can lead to hives, shortness of breath, and other symptoms.” Allergies to milk, eggs, and shellfish are all common examples.
Food intolerances, on the other hand, are instances where your digestive system may not produce the enzymes needed to properly break down a food, or may otherwise react improperly to certain foods. This is the case for people suffering from lactose intolerance. Symptoms tend toward abdominal pain, bloating, and diarrhea, and your immune system’s antibody reactions usually aren’t involved, Ogbogu says. “Food allergies are less common among adults, while intolerances are very common,” she explains.
Sensitivities are a third, harder-to-nail-down category. Your immune system may get involved—though not to the extent that it does if you have an allergy. A lot of it seems dependent on the individual, and there may be some overlap with other gut conditions like irritable bowel syndrome and leaky gut. Again, experts are still sorting all this out. (Here’s the single biggest thing you can do for a healthier gut.)
What causes all these food-related gut issues to show up in some people and not in others? That’s tricky. Ogbogu says the human gut is complex, and figuring out how these conditions present is difficult. But there are a few possible or proven triggers.
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Your gut, as you’ve probably heard, is home to hundreds of billions of bacteria, which are collectively known as your microbiome. Those bacteria play a lot of roles in your health, including helping your body digest food. If you’re taking an oral antibiotic to wipe out a virus or infection, you’re also wiping out plenty of helpful gut bacteria in the process, Ogbogu says. And in some cases, that mass die-off can lead to “temporary problems” with digestion, she says. While it’s a source of debate, some research has also linked the use of antibiotics in food production to new-onset allergies.
It makes sense that carpet-bombing your microbiome with antibiotics could lead to changes in the way your gut digests food. But experts only recently started to grasp the importance (and delicacy) of the human gut’s ecosystem of microorganisms. They’re still trying to figure out exactly how antibiotics and your digestive capabilities interact. If you do need to take an antibiotic, consider incorporating more probiotic-rich fermented foods into your diet or taking a probiotic supplement (ideally at night, several hours after your antibiotic) to help replenish those good gut bugs.
Viruses and infections
Research from the Medical College of Wisconsin has turned up links between stomach flu-causing viruses like norovirus and food allergies—at least in mice. In that study, the mice exposed to norovirus showed a heightened allergic response to egg proteins. Again, details are murky. But it’s possible that the gut damage resulting from a bad stomach bug could lead to temporary intolerances or longer-term allergies, the research suggests.
A tick bite can trigger an allergy to meat. Yes, you read that right. Suffer a bite from a Lone Star Tick—a type common in much of the US—and your immune system registers the tick’s saliva as an intruder. Unfortunately, that saliva may contain a type of carbohydrate called “alpha-gal.” Alpha-gal is also found in meat. Once your immune system deems alpha-gal an enemy, you may suffer an allergic reaction whenever you eat animal flesh. (Here are 5 ways to keep ticks out of your yard and avoid Lyme and other tick-borne diseases.)
While this condition, known as alpha-gal syndrome, is thought to be relatively rare, there are at least known 3,500 cases (and climbing).
“Newer information now being studied suggests inflammation in the gastrointestinal tract may in fact have an impact in modifying the microbiome in the intestine [in ways]that may lead to food intolerance,” says Clifford Bassett, MD, a clinical assistant professor at New York University’s Langone Medical Center and a spokesperson for the American College of Allergy, Asthma and Immunology. The exact causes of chronic GI inflammation are numerous and, in many cases, hard to identify. But it may turn out that gut inflammation triggers or exacerbates food-related issues. (Some experts think taking a collagen supplement may help reduce GI inflammation.)