Probiotics are live microorganisms that confer a health benefit on the host. These beneficial bacteria, often from the Lactobacillus and Bifidobacterium genera, are commonly found in supplements or fermented foods. Histamine is a biogenic amine involved in the immune response, digestion, and neurotransmission. The relationship between probiotics and histamine is complex, and the effect a probiotic has on the body’s histamine levels is entirely dependent on the specific strain of bacteria used.
Understanding Histamine Intolerance
Histamine is synthesized in the body from the amino acid histidine. Once released, histamine acts as a signaling molecule, triggering inflammatory responses and regulating stomach acid secretion. The body manages this compound through rapid degradation, primarily via two enzymes: Diamine Oxidase (DAO) and Histamine N-methyltransferase (HNMT). DAO is the main defense against dietary histamine, synthesized by enterocytes to break down histamine before it enters systemic circulation. Histamine Intolerance (HI) occurs when there is an imbalance between histamine accumulation and the body’s capacity to metabolize it, often due to insufficient DAO or HNMT activity. Excess histamine can accumulate and trigger various symptoms, including digestive distress, headaches, and skin reactions.
Probiotics’ Dual Role in Histamine Levels
The influence of probiotics on histamine levels is complex because certain strains can either produce or degrade the compound. The ability of a bacterial strain to produce histamine is linked to the presence of the hdcA gene, which codes for the histidine decarboxylase enzyme. This enzyme allows the bacteria to convert the dietary amino acid histidine into histamine within the gut. Conversely, other probiotic strains actively support the breakdown of histamine, either by directly consuming it or by modulating the gut environment. Some beneficial bacteria stimulate the release of the DAO enzyme from intestinal cells, enhancing the body’s natural capacity to degrade histamine. An overgrowth of histamine-producing bacteria relative to degrading ones can contribute to the symptoms of histamine intolerance.
Identifying High and Low Histamine Probiotic Strains
The effect a probiotic has is highly strain-specific; even different strains within the same species can have opposite effects on histamine metabolism. Individuals with histamine sensitivity need to avoid strains known to possess the histidine decarboxylase enzyme, as these contribute to the total histamine load.
High Histamine Producers
Examples of potential histamine producers include certain strains of:
- Lactobacillus casei
- Lactobacillus delbrueckii
- Lactobacillus helveticus
Low Histamine or Degrading Strains
The search for low-histamine strains focuses on those confirmed not to express histidine decarboxylase. Many strains from the Bifidobacterium genus are generally considered safer. Specific Lactobacillus strains have also demonstrated histamine-lowering properties.
Examples of low-histamine or degrading strains include:
- Bifidobacterium longum
- Bifidobacterium infantis
- Bifidobacterium lactis
- Lactobacillus rhamnosus GG (LGG)
- Lactobacillus plantarum
These beneficial strains may help stabilize immune cells or downregulate receptors involved in histamine signaling.
Navigating Probiotic Supplements for Sensitivity
When selecting a probiotic supplement, individuals with histamine sensitivity must focus on the specific strain designation, not just the genus and species name. A complete probiotic name includes the genus, species, and a specific alphanumeric strain identifier, such as Lactobacillus rhamnosus GG. This strain specificity is the only reliable way to confirm whether a product contains a known histamine-neutral or histamine-degrading organism. It is prudent to avoid general probiotic blends that do not list the strain identifiers, as they may inadvertently contain histamine-producing bacteria. Fermented foods, such as sauerkraut, aged cheese, and kefir, are naturally high in histamine due to the microbial fermentation process and should be approached with caution, regardless of their beneficial bacteria content. Individuals introducing a new probiotic should start with a low dosage and gradually increase it while monitoring for adverse reactions.