Food poisoning can have lasting effects on health and may set off a condition called post-infection IBS. The connection lies in the gut microbiome and the brain.

Why some people don’t fully recover

Normally, once the digestive disturbance settles, food poisoning comes to an end. However, for some people, those first miserable days are only the beginning. The symptoms may not be intense, but diarrhoea and abdominal pain can persist for months or even years.

This is known as post-infection irritable bowel syndrome (IBS). Studies show that the risk of intestinal infection is higher when food poisoning outbreaks are linked to sprouts, lettuce, eggs, frozen blueberries and jalapeños.

When the gut doesn't bounce back

For decades, scientists have been trying to understand what causes this condition. The problem is that the damage may not be limited to one system but can affect several interconnected systems in the body.

A variety of germs can cause food poisoning and lead to bacterial infections. IBS isn’t the only digestive condition that can develop after an infection. Some people may also experience post-infection functional dyspepsia. Its symptoms include upper abdominal pain and an uncomfortable feeling of fullness after eating, which can easily go undetected.

The microbiome connection

Studies are inconclusive about why one person recovers completely while another develops lasting symptoms. Changes to the gut microbiome are one possible explanation. Following an infection, instead of returning to normal, the microbiome may rebuild itself differently. This can lead to the loss of certain beneficial microbes that may never return.

This can have a cascading effect, as certain gut bacteria help keep a range of illnesses at bay.

When the immune system takes a hit

The immune system may also be affected, leading to low-grade, persistent inflammation. One study suggests that gut infections can damage or kill neurons embedded in the intestinal wall, causing lasting changes in how the gut moves. The gut’s sensory system can also become hypersensitive in some patients.

Studies suggest that after food poisoning, the immune system produces antibodies to fight toxins released by certain bacteria. However, these antibodies may sometimes mistakenly attack the body’s own tissues, including cells that help regulate the small intestine. This can cause bacteria to multiply in the gut. The gases and other substances produced by these bacteria may increase gut sensitivity and make the intestinal lining more permeable. This can lead to irritation, inflammation, persistent diarrhoea and abdominal pain.

However, no single theory fully explains why some people develop IBS after an infection while others recover completely. Scientists are still trying to understand how these different factors are connected.

—manuvipin@newindianexpress.com

@ManuVipin