Onions and Bell Peppers in Low Histamine Diets
Onions and bell peppers are generally safe for consumption on a low histamine diet, as they are not considered high-histamine foods and are not typically excluded from low histamine dietary protocols.
Understanding Histamine Content in Foods
Histamine intolerance results from an imbalance between accumulated histamine and the body's capacity to degrade it, primarily through the enzyme diamine oxidase (DAO) 1. When considering foods for a low histamine diet, it's important to understand which foods actually contain significant histamine levels.
According to a comprehensive review of low-histamine diets, only certain plant-origin foods contain significant levels of histamine 2:
- Eggplant
- Spinach
- Tomato
- Avocado
Notably, onions and bell peppers are not included in this list of high-histamine plant foods.
Scientific Evidence on Onions and Bell Peppers
Research specifically examining low-histamine diets found great heterogeneity in the foods excluded across different dietary protocols 3. The only foods unanimously excluded were fermented foods, which neither onions nor bell peppers are. Only about 32% of foods excluded in low-histamine diets could be justified by their actual histamine content 3.
A study on biogenic amines in plant-origin foods confirmed that onions and bell peppers are not among the plant foods with significant histamine content 2. This supports their inclusion in a low-histamine diet.
Practical Dietary Recommendations
When following a low-histamine diet:
Focus on freshness: Consume onions and bell peppers when they are fresh, as biogenic amine content can increase with storage time 2.
Consider cooking method: Boiling vegetables can help reduce their biogenic amine content 2.
Be aware of individual variations: While onions and bell peppers are generally considered safe for low-histamine diets, individual tolerance can vary 4.
Watch for other biogenic amines: Some foods may contain other biogenic amines like putrescine that can compete with histamine for degradation by DAO 2. However, onions and bell peppers are not noted for high levels of these compounds.
Beyond Dietary Management
While diet is important, comprehensive management of histamine intolerance may include:
- DAO enzyme supplementation to support histamine degradation 4
- Second-generation H1 antihistamines when indicated, as recommended by the American Academy of Allergy, Asthma, and Immunology 5
- Avoiding medications that may increase histamine levels 5
Caution and Considerations
Despite the general safety of onions and bell peppers on a low-histamine diet, it's worth noting that:
- The diagnosis of histamine intolerance requires a complex, multidisciplinary approach 4
- A good response to a low-histamine diet is considered confirmation of histamine intolerance 4
- Individual responses to foods can vary, and some people may have idiosyncratic reactions even to foods not typically high in histamine 6
In conclusion, current scientific evidence supports that onions and bell peppers can be included in a low-histamine diet, as they are not significant sources of dietary histamine. However, individual tolerance should always be monitored, and freshness and proper preparation remain important factors in minimizing biogenic amine intake.