Food Intolerances & Food Sensitivities
Why Am I Suddenly Reacting to Foods? Understanding Food Intolerances and the Gut
If it feels like your body has suddenly decided that every meal is a problem, you're not alone.
One day you're eating normally, and the next you're bloated after an apple, uncomfortable after garlic, or convinced gluten and dairy are the enemy. It's understandable to assume you've developed multiple food intolerances.
But in many cases, the foods aren't actually the problem.
As a naturopath, I often explain to patients that food intolerances can sometimes be more like a warning light on the dashboard than the engine itself. The reaction may be real, but it doesn't necessarily tell us why it's happening.
Understanding the difference can be the key to getting back to eating a varied, enjoyable diet.
What is a food intolerance?
A food intolerance occurs when your body struggles to process or tolerate a particular food or food component, leading to symptoms such as bloating, abdominal pain or altered bowel habits.
Unlike a food allergy, which involves the immune system and can be life-threatening, food intolerances are generally not associated with severe allergic reactions such as anaphylaxis.
Common examples include:
Lactose intolerance
Fructose malabsorption
Sensitivity to FODMAP-rich foods
Caffeine intolerance
Alcohol intolerance
The important thing to remember is that not everyone reacts for the same reason.
Your gut isn't a static system
One of the biggest misconceptions is that food intolerances are permanent.
In reality, your ability to tolerate foods can change over time because your digestive system changes over time.
Think of your gut like a busy highway. When traffic is flowing well, everything moves smoothly. But if there's congestion, roadworks or an accident, problems start appearing everywhere.
The same can happen within the digestive tract.
If something is disrupting normal digestive function, foods that were previously well tolerated may suddenly start causing symptoms.
Sometimes it's not the food at all
Many people spend years chasing the next food to eliminate.
First gluten.
Then dairy.
Then onions.
Then apples.
Eventually the list becomes so restrictive that eating out becomes stressful and meals feel overwhelming.
While individual food triggers certainly exist, reacting to multiple foods may suggest that an underlying digestive issue deserves investigation.
Potential contributors can include:
Altered gut motility
Changes in the gut microbiome
Previous gastrointestinal infections
Coeliac disease
Enzyme deficiencies such as lactose deficiency
Addressing these factors may improve food tolerance rather than simply expanding the list of foods to avoid.
Food reactions and gut barrier function
When food reactions keep expanding, the answer is not always to remove more foods.
In some cases, increasing food sensitivity may be connected to gut barrier dysfunction, intestinal permeability, inflammation, dysbiosis, histamine intolerance, SIBO, stress physiology or immune activation in the gut.
The goal is to understand why tolerance has reduced, then rebuild the diet carefully where possible.
Why do FODMAP foods cause so many problems?
Many foods that people blame contain fermentable carbohydrates known as FODMAPs.
These carbohydrates are poorly absorbed in some individuals and can be fermented by bacteria within the gut, producing gas and drawing water into the bowel.
This is why foods as different as apples, onions, garlic and wheat can all trigger similar symptoms.
Rather than being "bad foods", they may simply expose an underlying sensitivity within the digestive system.
You can read more about FODMAPS here.
Is it really gluten?
Gluten often gets the blame.
However, wheat contains more than just gluten.
It also contains fructans, which belong to the FODMAP family and commonly trigger symptoms in people with IBS.
This means some people who believe they're reacting to gluten may actually be reacting to fructans instead.
Before removing gluten completely, it's important that coeliac disease is appropriately investigated while gluten is still being consumed, as testing may become unreliable once it has been eliminated.
Why do symptoms seem so inconsistent?
Patients often tell me: "I ate it last week and felt fine."
That's actually quite common.
Food reactions can depend on many factors, including:
The quantity eaten
The combination of foods in the meal
Stress levels
Sleep
Hormonal changes
Overall FODMAP load across the day
Gut motility
It's often the accumulation of several factors rather than one single ingredient.
Should you order an online food sensitivity test?
Many commercially available IgG food sensitivity tests are heavily marketed but remain controversial and are not widely accepted as diagnostic tools for identifying clinically meaningful food intolerances.
Results can sometimes reflect regular exposure to foods rather than indicating that those foods should be avoided.
A detailed clinical history, appropriate medical investigations where indicated and a structured dietary assessment are often more informative.
Can eliminating foods make things worse?
Temporary elimination diets have their place when used appropriately and under guidance.
However, continually removing more and more foods without understanding why symptoms are occurring can have unintended consequences.
Overly restrictive diets may:
Reduce fibre intake
Reduce beneficial polyphenol intake
Negatively affect the gut microbiome
Increase anxiety around eating
Make social situations more difficult
The long-term goal should ideally be to expand your diet wherever possible, not shrink it.
When should you seek further assessment?
If you're reacting to an increasing number of foods or experiencing persistent digestive symptoms, it's worth exploring whether there's an underlying issue contributing to those reactions.
You should also seek medical assessment if symptoms are accompanied by:
Unintentional weight loss
Blood in the stool
Ongoing diarrhoea
Night-time symptoms that wake you
A family history of bowel disease
Symptoms that persist despite dietary changes
The bottom line
Food intolerances are real, but they don't always tell the whole story.
If your list of trigger foods seems to be growing every month, it may be time to ask a different question.
Instead of focusing solely on "Which food am I reacting to?", consider "Why has my body started reacting in the first place?"
For many people, identifying and addressing the underlying digestive issue is what allows them to enjoy a broader, less restrictive diet again.