Histamine Intolerance and the Link with SIBO: Understanding the Gut-Histamine Connection
If you're experiencing mysterious digestive issues, brain fog, skin rashes, or headaches that seem to come out of nowhere, you might be familiar with histamine intolerance (HI) or small intestinal bacterial overgrowth (SIBO). These conditions are complex and often misunderstood, but what you may not know is that they can be closely linked. Understanding how these two conditions interact can offer valuable insight into managing your symptoms and improving your overall health.
In this blog post, we’ll explore how histamine intolerance and SIBO are connected, how they impact your body, and what you can do to support your gut health.
What is Histamine Intolerance?
Histamine is a chemical involved in many critical functions in your body. It helps regulate your immune response, digestion, and central nervous system. When everything is working properly, your body can break down and metabolize histamine efficiently. However, histamine intolerance occurs when there's too much histamine in your body, or your body can't break it down quickly enough.
Key symptoms of histamine intolerance include:
Headaches or migraines
Digestive issues like bloating, diarrhoea, and stomach cramps
Skin reactions, such as itching, hives, or eczema
Respiratory issues like nasal congestion, wheezing and shortness of breath
Anxiety or irritability
Fatigue and brain fog
Insomnia
Low mood/Depression
Histamine intolerance happens when your DAO (diamine oxidase) and HNMT (histamine N-methyltransferase) enzymes, which break down histamine, are unable to keep up with the histamine levels in your body. When this occurs, the histamine builds up, triggering various symptoms.
What is SIBO?
Small Intestinal Bacterial Overgrowth (SIBO) is a condition where bacteria, normally found in the large intestine, overgrow in the small intestine, where they aren’t supposed to be in such high numbers. The bacteria in the small intestine ferment food prematurely, particularly carbohydrates, leading to a variety of uncomfortable symptoms, such as:
Bloating and Gas
Abdominal pain
Diarrhoea and/or Constipation
Belching and Reflux
Nutrient deficiencies, due to malabsorption
Food Intolerances
While the symptoms of SIBO primarily affect the digestive system, this condition can also lead to inflammation and affect overall gut health, which can have a ripple effect throughout the body.
How Are Histamine Intolerance and SIBO Linked?
The connection between histamine intolerance and SIBO lies in the gut.
Gut Dysbiosis: One of the main issues with SIBO is that it leads to an imbalance in gut bacteria, known as gut dysbiosis. Many of the bacteria that overgrow in the small intestine can produce histamine as a byproduct of fermentation. When these bacteria overproduce histamine in an already compromised digestive system, your body’s ability to break down histamine is further overwhelmed, exacerbating histamine intolerance symptoms.
Reduced DAO Activity: The enzyme DAO, which helps break down histamine in the gut, can be compromised by SIBO. Inflammation from SIBO may damage the lining of the small intestine (intestinal permeability or “leaky gut”), where DAO is produced, leading to decreased levels of this crucial enzyme. With less DAO available, your body has a harder time breaking down histamine from foods and internal sources, leading to histamine build-up and worsened symptoms.
Inflammation: Both SIBO and histamine intolerance can increase inflammation in the gut. Histamine plays a role in immune response, and when too much histamine is present, it triggers inflammation. SIBO itself also contributes to inflammation through bacterial overgrowth, which can perpetuate a cycle of gut irritation, poor digestion, and increased histamine levels.
Food Sensitivities: People with SIBO are often sensitive to foods high in fermentable carbohydrates (FODMAPs), which feed bacterial overgrowth in the small intestine. Additionally, many of these individuals may have sensitivities to high-histamine foods, which can worsen both SIBO and histamine intolerance symptoms. Foods like aged cheeses, fermented foods, alcohol, and processed meats are high in histamine and can trigger or exacerbate symptoms.
Managing Histamine Intolerance and SIBO
Since histamine intolerance and SIBO can feed into each other, addressing both conditions simultaneously is crucial for long-term relief. Here are some steps you can take to manage both:
1. Follow a Low-Histamine, SIBO-Friendly Diet
Diet is one of the most effective ways to manage both conditions. By reducing histamine-rich foods and focusing on a low-FODMAP diet, you can reduce the triggers that feed bacterial overgrowth and histamine production. Foods to avoid on a low-histamine diet include:
Fermented and preserved foods (e.g., vinegar, pickles, sauerkraut, kombucha, yogurt)
Aged cheeses and processed meats
Fish that is not fresh
Tomatoes, spinach, eggplant, and avocado
Alcohol, especially wine and beer
Leftover foods, as histamine levels increase in stored foods
Smoked produce e.g smoked salmon
For SIBO, a low-FODMAP approach can help reduce bacterial fermentation in the small intestine. Focus on whole, unprocessed foods, and work with a nutritionist to create a plan that minimises symptoms for both conditions. Restrictive diets like these should only be used as symptom management for a short period of time. In the long term restrictive diets can do more harm than good, due to how they alter the species in our gut and the nutrients we derive from a variety of foods.
2. Support Gut Health with Probiotics and Prebiotic Fibres (Cautiously)
Certain probiotics can be helpful in managing SIBO and histamine intolerance. However is important to note that some probiotics can also worsen symptoms; not all probiotics are created equal, and some may actually produce histamine or cause further digestive issues. Opt for histamine-degrading probiotics such as:
Bifidobacterium infantis
Bifidobacterium longum
Lactobacillus rhamnosus
Avoid strains like Lactobacillus casei and Lactobacillus bulgaricus, as they can increase histamine production. Always introduce probiotics slowly and monitor your symptoms.
A safer option is consuming specific prebiotic fibres such as PHGG (partially hydrolysed guar gum) which feed good bacteria in the gut, improves SIBO treatment outcomes and can reduce IBS symptoms. Be cautious with other prebiotic fibres as these can make digestive symptoms worse, so always work with a nutritionist.
3. Use DAO Supplements
For those with histamine intolerance, DAO supplements can be helpful when taken before meals. These supplements provide your body with additional DAO enzymes, helping break down dietary histamine before it enters your bloodstream. My personal favourite is Lamb Kidney Capsules by Hunter and Gather, lamb kidney is particularly high in DAO.
4. Antimicrobial Treatment for SIBO
If you have SIBO, antimicrobial treatments—either pharmaceutical or herbal—are often necessary to reduce the bacterial overgrowth. This can help restore balance to your gut, lower inflammation, and support histamine metabolism. Always consult with a healthcare professional before starting any antimicrobial treatment.
5. Manage Stress
Stress significantly impacts gut health and can worsen both SIBO and histamine intolerance. Incorporating stress-management techniques like deep breathing, yoga, or meditation into your daily routine can help reduce gut inflammation and promote healing.
The Bottom Line
Histamine intolerance and SIBO often go hand-in-hand, feeding into one another and making symptoms worse. Understanding the connection between these two conditions can help you better manage your symptoms and restore balance to your gut. By following a tailored diet, supporting gut health with the right supplements, and addressing bacterial overgrowth, you can find relief and start feeling better.
If you suspect you have histamine intolerance or SIBO, it’s important to work with a healthcare professional or nutritionist to develop a personalised plan. Your gut health is key to your overall well-being, and with the right approach, healing both is possible!