5 Signs That Fermented Foods Are Incompatible with Your Body—Plus What the Underlying Triggers May Be

Whether I’m munching and crunching on fermented foods or sipping on them in kombucha and kefir soda form, I truly can’t get enough of these mouth-puckering delights. I’m fortunate in that they’re as kind on my palate as they are to my body… but I know that not everyone can say the same thing. If you love the likes of kimchi, Greek yogurt, and fermented bevs as much as I do—yet have a sneaking suspicion that they don’t quite love you back—it can help to know of the key signs that they’re incompatible with your body.

To figure out how to tell if fermented foods are simply not the right fit in your diet and for your body’s needs (as well as why that might be), we consulted Kenneth Brown, MD, a board-certified gastroenterologist in Plano, Texas.

Why fermented foods aren’t universally beneficial

“Fermented foods are an excellent way to improve your gut health, as they contain beneficial bacteria that can help restore the balance of microorganisms in your digestive system,” Dr. Brown says. Particularly in those that contain probiotic cultures, fermented foods “have been linked to various health benefits, such as reducing symptoms of lactose intolerance, inflammatory bowel disease (IBD), Crohn’s disease and ulcerative colitis, irritable bowel syndrome (IBS), gastroenteritis, diarrhea, and even cancer.” While Dr. Brown says that such foods can typically help to balance your gut, improve digestion, and offer a range of additional perks, fermented foods aren’t a safe and sure bet for everyone.

“Some people may have difficulty digesting fermented foods due to sensitivity or allergies, or because their digestive systems cannot properly break down and absorb the nutrients in these foods,” Dr. Brown says. For instance, Greek yogurt and kefir may cause trouble in those who are sensitive to dairy. In addition, fermented foods can be high in fiber, which may cause discomfort in people who don’t typically consume it (or don’t rev up hydration with increased intake).

Another potential culprit may be excess sugar, which the gastroenterologist says may contribute to digestive symptoms in some people. Moreover, Dr. Brown reminds us that fermented foods are high in histamine. “Many people have a histamine intolerance they are unaware of,” he continues, which may explain why you feel worse for wear after eating (or drinking) the fermented fare of your choice.

“Some people may have difficulty digesting fermented foods due to sensitivity or allergies, or because their digestive systems cannot properly break down and absorb the nutrients in these foods,” says Dr. Brown.

5 telltale signs that your body can’t handle fermented foods, or that you have a fermented foods sensitivity

Strangely enough, many of the benefits that fermented foods can offer for one person may yield the exact opposite in another. For instance, digestive effects aside, studies show that kimchi can help to tame eczema flare-ups—but as you’ll see below, it may potentially drive skin inflammation, as well.

If you suspect that fermented foods may be doing more harm than good in your body, keep tabs on the following side effects the next time you consume them:

1. Gas and bloating

Dr. Brown notes that fermented foods may produce gas while you’re digesting them. A little flatulence may not be a major warning sign—unless it leads to bloating and discomfort.

2. Stomach pain and cramping

If you feast on a forkful of sauerkraut and experience a massive tummy ache shortly after, there’s a chance that fermented foods are incompatible with your system. “This can be a sign of irritation or inflammation in the digestive system,” Dr. Brown shares, citing the acidic properties of fermented foods as a potential culprit. In this case, he also advises against eating fermented foods on an empty stomach, which he says can heighten digestive discomfort if other foods aren’t there to “buffer” the acidity.

3. Diarrhea

Although fermented foods can help to alleviate diarrhea in some people, they can actually trigger it in others. “The beneficial bacteria in these foods can alter the balance of microorganisms in the digestive system and lead to changes in bowel movements,” says Dr. Brown.

4. Inflammatory skin conditions

Have you ever developed a rash (or another inflammatory skin reaction) after eating fermented foods? “This can be a sign of histamine intolerance or an allergy,” Dr. Brown explains.

5. Anxiety

According to Dr. Brown, many fermented foods have lactate-producing probiotics, which may trigger or exacerbate anxiety in certain individuals. “A recent study showed that people with small intestinal bacterial overgrowth (SIBO) had higher levels of lactic acid and anxiety when consuming probiotics,” he shares. As such, people with this GI condition (or those who suspect they may have it, based on their symptoms), may want to cease consuming fermented foods and/or consult a gastroenterologist to get to the root of the problem.

All things considered, Dr. Brown champions fermented foods and often recommends that his patients eat more of them. But if they trigger digestive distress and other adverse effects, further investigation will be required. “If they cannot tolerate these foods, we should consider potential underlying issues—such as SIBO or histamine intolerance—and fix those issues first,” he concludes.