Why Are So Many Women Developing Food Intolerances?

One of the most common things women are saying to me right now is this:

“I seem to be reacting to everything.”

Foods they’ve eaten for years suddenly cause bloating, headaches, skin flares, anxiety, reflux, fatigue, or that vague but unmistakable sense that something isn’t right. Gluten, dairy, eggs, histamine-rich foods, even healthy staples like avocado or nuts start to feel like enemies.

This isn't a coincidence, and it isn't a weakness. It’s information.

From a functional medicine perspective, food intolerances are rarely about the food itself. They’re a signal that something upstream has shifted.

What is a Food Intolerance?

It’s also important to distinguish food intolerances from true food allergies, as they are not the same thing. A food allergy is an immediate, immune-mediated response (typically involving IgE antibodies) and can cause rapid symptoms such as hives, swelling, breathing difficulty or anaphylaxis. Food intolerances, on the other hand, are usually delayed, dose-dependent and cumulative. They don’t involve an acute allergic reaction, but rather reflect how well the gut, immune system and nervous system are coping. Symptoms may appear hours or even days later and can affect digestion, skin, mood, energy, hormones or inflammation. From a functional medicine perspective, intolerances are best understood not as an allergy to food, but as a loss of tolerance — a sign that the digestive and regulatory systems are under strain.

Functional Reasons Food Intolerances Develop

Food intolerances don’t appear out of nowhere. They tend to emerge when the gut–immune–nervous system axis is under sustained pressure. Common drivers I see in practice include:

1. Increased intestinal permeability (the “leaky gut” picture)

When the gut lining becomes inflamed or compromised, partially digested food particles can cross into the bloodstream. The immune system does its job and flags them as potential threats. Over time, this can look like “sudden” reactions to multiple foods.

2. Chronic stress and nervous system overload

Digestion is not just mechanical; it’s neurological. When the body is stuck in fight-or-flight, stomach acid, enzymes, bile flow and gut motility all suffer. Poorly digested food is far more likely to trigger symptoms.

3. Low stomach acid and digestive enzymes

This is especially common in busy women, those under stress, postpartum, or in perimenopause. If food isn’t properly broken down, it becomes irritating rather than nourishing.

4. Gut microbiome imbalance (dysbiosis)

Beneficial bacteria help us tolerate and metabolise foods. When diversity drops or opportunistic microbes dominate, foods that once felt fine can suddenly cause gas, bloating, histamine reactions or inflammation.

5. Repeated antibiotic use or long-term medication exposure

Antibiotics, PPIs, NSAIDs and some hormonal medications can all alter gut integrity and microbial balance, sometimes long after they’ve been stopped.

6. Hormonal shifts (especially perimenopause)

Oestrogen influences gut permeability, bile flow, histamine balance and immune tolerance. Hormonal fluctuations can lower the threshold at which foods start causing symptoms.

7. A cumulative inflammatory load

This is rarely one thing. It’s often stress + poor sleep + nutrient depletion + infections + life. Eventually the bucket overflows, and food becomes the most obvious trigger.

Why Cutting Out More and More Foods Isn’t the Long-Term Answer

Eliminating reactive foods can be genuinely helpful in the short term. A guided elimination period can lower the inflammatory burden, calm symptoms, and give the gut space to recover.

But elimination alone is not healing.

If the underlying drivers aren’t addressed, the list of “safe” foods often shrinks rather than expands. What starts as gluten-free can become gluten-, dairy-, egg-, histamine-, sugar- and joy-free.

The real work is not about avoiding foods forever. It’s about understanding why the gut has lost tolerance in the first place and supporting it back towards resilience.

That means looking at digestion, gut lining integrity, microbial balance, immune signalling, stress physiology and lifestyle factors together – not in isolation.

When the gut heals, tolerance often improves. Foods stop feeling like threats. Eating becomes simpler again.

Food intolerances are not a personal failure or a life sentence. They are the body asking for attention, context and care. When we listen properly, they can become a starting point for deeper healing rather than a narrowing of life.

This is exactly the kind of work I see quietly transforming women’s health when we stop asking “what food should I cut out next?” and start asking “what is my gut actually asking for?”

And that shift changes everything.

If this resonated, I share more like this — practical and sustainable information and tips — in my newsletter. Click HERE to sign up