Why You’re Reacting to Foods You Used to Tolerate

Why This Is Happening to So Many People

One of the most important things to understand about modern digestive symptoms is this: you don’t need a dramatic backstory for them to appear. You don’t need a diagnosed condition, a major illness, or a single obvious trigger. I see this pattern constantly in practice, in people from all walks of life, people who are functioning, working, raising families, exercising, and often being told that everything looks “normal”.

For many people, symptoms don’t arrive because of one big event. They arrive because of accumulation.

Modern life places a quiet but persistent load on the digestive system. Over time, that load reduces digestive capacity, enzyme output drops, bile flow becomes less efficient, and nervous system signalling to the gut weakens. Eventually, the system reaches a point where it can no longer compensate in the way it once did. That’s usually when people start reacting to foods they’ve eaten for years without any issue.

One of the most common contributors is the use of PPIs and acid-suppressing medications. These are often prescribed to manage symptoms, but stomach acid is a critical part of digestion. It triggers enzyme release, supports bile flow, and helps break food down before it reaches the small intestine. When acid is suppressed long-term, digestion becomes incomplete, immune activation increases, and tolerance to foods gradually narrows.

Other medications can have a similar impact without people realising. Some affect gut motility, slowing the movement of food through the digestive tract. Others interfere with bile flow or enzyme secretion. Individually, these effects may seem mild, but over months or years they place ongoing strain on digestive function.

Antibiotics are another major factor. While they can be life-saving when necessary, they significantly alter the gut–immune balance. Many people never fully recover digestive resilience after repeated courses. The gut becomes more reactive, immune signalling increases, and foods that were once tolerated begin to cause symptoms.

Vaccinations act as an additional stressor. They are designed to activate the immune system, which is usually temporary. However, in someone already carrying digestive strain, nervous system dysregulation or toxic load, this immune activation can be enough to tip the system into symptoms. This isn’t about blame, it’s about understanding cumulative load.

Emotional factors are often underestimated. Grief, shock, trauma and prolonged stress have a direct impact on digestion. When the nervous system is in survival mode, digestion is downregulated. Enzyme output drops, bile flow slows, and blood flow is redirected away from the gut. Many people notice digestive symptoms emerging weeks or months after an emotional event, without ever connecting the two.

Layered on top of all of this is the reality of poor-quality, ultra-processed foods. Even when eaten “in moderation”, these foods demand far more from digestive enzymes and bile than whole, simple foods. Over time, they quietly erode digestive efficiency, especially when combined with stress, medication use or immune activation.

Individually, many of these factors can be tolerated. The body is remarkably adaptable. But when they accumulate, often slowly, over years, digestive resilience decreases. Eventually, the system reaches a tipping point. Symptoms appear, not because the body is broken, but because it has reached capacity.

This is why so many people feel confused when digestion suddenly feels fragile. Nothing dramatic has happened. There hasn’t been a single cause. The body has simply been compensating for a long time, and that compensation has limits.

Understanding this changes the response completely. Instead of fear, restriction or chasing labels, the focus becomes reducing load, restoring digestive support, calming the nervous system and allowing capacity to rebuild. When that happens, many people find that foods they once reacted to become tolerable again.

This pattern is far more common than most people realise. And in many cases, with the right support, it is not only understandable, it is reversible.