Histamine is a naturally occurring chemical compound classified as a biogenic amine found in various foods. This compound plays a role in local immune responses, acts as a neurotransmitter, and regulates stomach acid production within the body. The question of whether dried herbs contain amounts of histamine that could cause reactions is particularly relevant for people who experience sensitivity to dietary amines.
Understanding Histamine and Intolerance Sensitivity
Many people ask about histamine in foods because they experience a condition known as histamine intolerance. This is not a true allergy but rather a digestive disorder that results from an imbalance between the amount of histamine consumed and the body’s ability to break it down. Symptoms of this imbalance can affect multiple body systems, presenting as headaches, digestive upset, skin flushing, or hives. The body primarily relies on two enzymes to metabolize histamine: Diamine Oxidase (DAO) and Histamine N-methyltransferase (HNMT).
The DAO enzyme is largely responsible for breaking down ingested histamine in the digestive tract. When DAO activity is low, or the consumed histamine load exceeds the enzyme’s capacity, the chemical accumulates in the bloodstream. HNMT works inside cells to break down histamine that is produced internally by the body. The functional capacity of these enzymes, which can be influenced by medications, gastrointestinal conditions, or genetic variations, determines an individual’s tolerance threshold for dietary histamine.
How Drying and Storage Affect Histamine Levels
The process of converting fresh herbs into dried products can significantly impact their final histamine content. One primary mechanism is the simple effect of concentration, where the removal of water concentrates all existing compounds, including biogenic amines, into a smaller mass. The other major factor contributing to higher amine levels is microbial activity, which is often influenced by the drying and storage conditions. Biogenic amines like histamine are formed when microorganisms, such as certain types of bacteria, decarboxylate amino acids found in the food.
This process is a common aspect of food spoilage, fermentation, and aging. If drying is not performed rapidly and thoroughly, or if the herbs are stored improperly, residual moisture can support the growth of these amine-producing bacteria. Traditional or sun drying methods, due to extended time and conditions, may provide a window for microbial proliferation, potentially increasing histamine levels. A properly dried and sealed herb should have minimal microbial activity, but the initial concentration effect remains.
Some advanced methods, such as freeze-drying, have been shown to result in lower amine levels compared to traditional drying techniques. Nevertheless, the general rule in managing histamine sensitivity is to be cautious with all preserved or aged foods, which includes most dried herbs and spices.
Specific Histamine Content in Common Dried Herbs
Determining the exact histamine content of any dried herb is challenging, as levels can vary widely based on the specific strain, drying method, age, and storage conditions. Despite this variability, general guidelines exist for categorizing common herbs and spices for those managing histamine intolerance. A number of fresh herbs are widely considered to be low in histamine and well-tolerated when dried.
Leafy herbs considered low in histamine include:
- Basil
- Oregano
- Thyme
- Parsley
- Rosemary
Other spices like ginger and turmeric are also frequently listed as being compatible with a low-histamine diet.
A separate group of spices are frequently associated with higher histamine levels or are known to act as “histamine liberators,” triggering the body’s own cells to release histamine. Caution is advised with spices like cinnamon, cloves, and nutmeg. These concentrated spices are commonly noted as potential triggers for symptoms in sensitive individuals. Complex spice blends, such as curry powder and chili powder, are also commonly excluded from low-histamine diets because they often contain multiple high-histamine ingredients or compounds that can block the DAO enzyme.
It is also important to consider the potential for cross-contamination or degradation in commercially packaged dried herbs. Exposure to moisture or light during storage can initiate microbial activity even in a product that was low-histamine when initially dried. Individuals managing histamine sensitivity should prioritize single-ingredient herbs that are fresh and properly stored, using any dried variety in small amounts to assess personal tolerance.