Can Gut Health Cause Temporary Food Intolerances?
Have you ever been able to eat a food without any problems, only to suddenly find that it causes bloating, gas, abdominal pain or diarrhoea? You might assume you've developed a permanent food intolerance. But sometimes, the issue may not be the food itself. Changes within the gut microbiome, intestinal lining, digestion and gut sensitivity can influence how well you tolerate certain foods. This is particularly relevant for people experiencing IBS, bloating and digestive symptoms.
How does the gut microbiome affect food tolerance?
The gut microbiome contains trillions of microorganisms that help ferment parts of the food we eat, particularly carbohydrates that aren't fully digested in the small intestine. This fermentation is a normal and important part of digestion. However, changes in the microbiome, gut motility or intestinal sensitivity can alter how someone responds to fermentable foods. Lactose is a good example. Lactose that isn't fully digested reaches the colon, where bacteria ferment it, producing gas and other compounds. Symptoms can depend on the amount of lactose consumed, gut transit time, the composition of the microbiome and how sensitive the gut is to distension. This means that food tolerance isn't always fixed.
Can gut problems cause temporary food intolerance?
Yes, in some circumstances.
For example, damage to the small intestinal lining following a gastrointestinal infection or another intestinal condition can temporarily reduce lactase activity. This can result in secondary lactose intolerance even in someone who previously tolerated dairy. As the underlying intestinal problem improves, lactose tolerance may also improve. This is an important distinction because removing dairy permanently may not always be necessary. The same principle can apply more broadly to digestive symptoms. Following an infection or during a period of IBS, the gut can become more sensitive to fermentation, distension and changes in bowel movements.
What about FODMAPs and IBS?
FODMAPs are a group of fermentable carbohydrates found in many healthy foods, including certain fruits, vegetables, pulses, wheat products and dairy.
For some people with IBS, these carbohydrates can contribute to bloating, abdominal pain, gas and altered bowel habits because they are fermented in the gut and can increase intestinal water and gas.
Research shows that a low-FODMAP diet can improve symptoms for many people with IBS. However, research also shows that reducing FODMAP intake can alter the gut microbiome, including reducing levels of beneficial Bifidobacteria.
This is why I don't recommend thinking of FODMAP foods as simply “bad” foods.
Instead, the goal should be to understand which foods, quantities and combinations are triggering symptoms and why.
Why you might suddenly stop tolerating foods
Temporary changes in food tolerance may occur alongside:
Gastrointestinal infections or food poisoning
Changes to the intestinal lining
IBS and increased gut sensitivity
Changes in gut motility
Alterations in the gut microbiome
Significant dietary changes
Antibiotic use
Periods of increased digestive stress
It is also possible to mistake gut sensitivity for a food intolerance. Research has found that people with IBS who believe they are lactose intolerant do not always have confirmed lactose malabsorption.
This is why identifying the underlying cause is often more useful than simply removing more and more foods.
Should you eliminate the food?
Not necessarily.
If a food is causing symptoms, temporarily reducing it may be helpful while you investigate what's happening. However, unnecessary long-term restriction can make your diet increasingly limited and potentially affect nutritional adequacy and the diversity of foods reaching your gut microbiome.
For some people, a structured elimination and reintroduction process can help establish what they actually tolerate.
The aim isn't to end up with a long list of foods you can't eat. It's to find the widest, most varied diet you can comfortably tolerate.
The bottom line
Your ability to tolerate a food can change.
Sometimes what appears to be a new food intolerance may actually reflect changes in gut health, digestion, the microbiome or gut sensitivity.
Rather than asking only:
“Which foods are causing my symptoms?”
It can be more helpful to ask:
“Why am I reacting to these foods now?”
Understanding the underlying digestive picture can help you move away from unnecessary food restriction and towards a more personalised approach to gut health.
If you're struggling with bloating, IBS, food intolerances or ongoing digestive symptoms, working with a qualified nutritional therapist can help you investigate potential triggers and develop a practical, personalised nutrition strategy.
References
Misselwitz B, et al. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. Gut. 2019.
Leis R, et al. Effects of Prebiotic and Probiotic Supplementation on Lactase Deficiency and Lactose Intolerance: A Systematic Review of Controlled Trials. Nutrients. 2020.
So D, et al. Effects of a low FODMAP diet on the colonic microbiome in irritable bowel syndrome: a systematic review with meta-analysis. American Journal of Clinical Nutrition. 2022.
Varjú P, et al. Efficacy of a low-FODMAP diet in adult irritable bowel syndrome: a systematic review and meta-analysis. Nutrients. 2021.
Pop A, et al. Self-Perceived Lactose Intolerance Versus Confirmed Lactose Intolerance in Irritable Bowel Syndrome: A Systematic Review. Journal of Gastrointestinal and Liver Diseases. 2024.
Usai-Satta P, et al. Lactose malabsorption and intolerance: What should be the best clinical management? World Journal of Gastrointestinal Pathophysiology. 2012.
