Could Histamines Be the Hidden Cause of Your Symptoms?

Do you experience recurring headaches, hives, nasal congestion, or unexplained fatigue? You might chalk them up to allergies or stress but histamine intolerance could be playing a bigger role than you think.

What Is Histamine and Why Does It Matter?

Histamine is a natural chemical produced by your immune system. It plays several important roles in the body, including:

• Fighting off allergens and pathogens

• Supporting digestion

• Acting as a neurotransmitter in the brain

  
  

But problems can arise when your body struggles to break histamine down effectively. This condition - known as histamine intolerance - can result in an overload of histamine in the bloodstream, leading to symptoms that mimic allergic reactions.

What Causes Histamine Intolerance?

Histamine intolerance is most commonly linked to a deficiency in diamine oxidase (DAO) - an enzyme responsible for breaking down histamine in the gut. If DAO isn’t working properly, or if histamine levels are simply too high, symptoms can appear. Contributing factors include:

• Genetics - Some people naturally produce less DAO.

• Gut inflammation - Conditions like SIBO, leaky gut, and IBD reduce DAO production.

• Medications - NSAIDs, antidepressants, and antihistamines can block DAO activity.

Another enzyme, Histamine-N-Methyltransferase (HNMT), helps break down histamine in the brain and liver. Genetic mutations in HNMT may contribute to neurological symptoms like migraines, insomnia, or anxiety.

Common Symptoms of Histamine Intolerance

Because the symptoms overlap with other conditions, histamine intolerance often goes undiagnosed. Common signs include:

• Headaches or migraines

• Facial flushing

• Hives or itchy skin

• Digestive issues (bloating, diarrhoea, reflux)

• Low blood pressure or heart palpitations

• Fatigue, brain fog, or anxiety

An elimination diet, guided by a healthcare professional, is the best way to identify whether histamine is triggering your symptoms.

Foods High in Histamine

Histamine levels in food increase as they age (i.e. the longer you have them in the fridge or cupboard). If you’re histamine-sensitive, avoiding or limiting the following can help:

• Fermented foods (sauerkraut, kimchi, yogurt)

• Aged cheeses

• Alcohol (especially wine and beer)

• Processed meats (salami, ham)

• Certain vegetables (tomatoes, spinach, aubergine)

• Non-fresh fish (canned, smoked, or leftover seafood)

The MCAS Connection

Histamine intolerance and Mast Cell Activation Syndrome (MCAS) are often confused, but they are different:

• Histamine intolerance involves impaired histamine breakdown.

• MCAS involves overactive mast cells releasing too much histamine and other inflammatory compounds.

The two conditions can overlap, and people with MCAS may benefit from a low-histamine diet during symptom flare-ups.

Healing the Gut with the 5R Approach – Modified for Histamine Intolerance

The 5R Framework is a tried-and-tested method in Functional Medicine. Here’s how it applies to histamine sensitivity:

1. REMOVE - Inflammatory & High-Histamine Foods

Avoid aged, fermented, and processed foods, as well as common gut irritants like gluten, dairy, and refined sugar.

2. REPLACE - Digestive Support (No Fermented Foods!)

Support digestion with betaine HCl, digestive enzymes, and histamine-friendly herbs like ginger and dandelion root.

3. REINOCULATE - Restore Gut Bacteria Safely

Use low-histamine probiotic strains like Bifidobacterium infantis and feed your good bacteria with prebiotic foods like green bananas and cooked, cooled rice.

4. REPAIR - Soothe the Gut Lining

Support healing with collagen (instead of bone broth if you’re sensitive), quercetin, zinc, vitamin C, and omega-3s.

5. REBALANCE - Manage Stress & Sleep

Stress and poor sleep can worsen histamine reactions. Incorporate meditation, gentle movement, and herbs like peppermint and nettle to lower your histamine load.

Supplements That Can Help

DAO enzyme supplements can support histamine breakdown and reduce symptoms like reflux, bloating, and headaches.

⚠️ Note: Always speak with a qualified medical professional before beginning a new supplement or protocol.

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