What is Histamine?
Histamine is a neurotransmitter involved in several bodily processes including the immune and the nervous systems. Its function is to initiate an immune response when an injury or an infection occurs. It is naturally found in all cells of our body, but it is also found in certain foods, particularly fermented foods.
Histamine intolerance:
Most people tolerate the amount of histamine found in the diet. However, if levels get too high, there are consequences such as itching, sneezing, headaches, joint pain and nausea. This mismatch between the high levels of histamine and the speed at which the body deposes of it is known as “histamine intolerance”. Histamine intolerance also known as food histaminosis or hypersensitivity to histamine, arises from the failure of the enzyme diamine oxidase (DAO) to degrade histamine at the intestinal level. As a result, DAO deficit leads to an increase of histamine levels and the subsequent onset of symptoms.
How much is too much? This is totally dependent on each individual. A person’s tolerance to histamine can be compared to a bucket filled with water. There are numerous factors that influence how full your histamine bucket might be. These include your genes, your diet, whether you have nutritional deficiencies or you suffer from environmental allergies like pollen. Women are generally more affected than men. Increased sensitivity to the intake of histamine is observed in women in the premenstrual phase. This is because histamine levels are likely to increase at ovulation just before menstruation.
Low-histamine diet:
The diet is one of the main factors affecting histamine tolerance. For instance, foods that have been naturally preserved through fermentation, souring, drying, smoking, or curing, have a high histamine content and they are more likely to trigger symptoms such as itchy skin, watery eyes, dizziness, headaches, and anxiety. Consequently, it is advised to adhere to a low-histamine diet and supplements with the DAO enzyme to facilitate histamine degradation. Several studies have shown that low-histamine diets are efficient in improving or remitting the symptoms.
Histamine in food is mainly formed by a bacterial reaction with its precursor amino acid, histidine. As a consequence, foods susceptible to accumulating high contents of this amine are those that are microbiologically altered by spoilage bacteria, such as fermented products.
There isn’t a specific set level below which a food is said to be low in histamine. In some research studies, histamine levels ranging between 5-50 mg/kg have been pointed out as potential thresholds, while others claim histamine levels are considered low when it is below 1mg/kg.
What does the low-histamine diet look like?
A low-histamine diet is a diet that consists of the elimination of many fermented foods including dry-fermented sausages, sauerkraut, cured cheese, kimchi, pickled vegetables, wine and beer. On the other hand, fresh products such as fresh meat, fresh fish or vegetables have a very low amount of histamine.
Histamine is also found in some plant-origin products such as tomato, eggplant and spinach, which should be avoided. Moreover, there are foods that have been tagged as histamine-liberators, as they trigger the release of histamine. Examples of these ones include citrus food (e.g., lemon), seafood, papaya, tomato, nuts, pineapple, spinach, chocolate and strawberries.
The below is a table that indicates foods that are high in histamine vs foods that are low in histamine:
The low-histamine diet and long Covid:
Scientists have found a relationship between long Covid and histamine release. Long Covid is defined as “symptoms that develop during or following an infection consistent with COVID-19 continuing for more than 12 weeks.” These symptoms include breathlessness, coughs, chest pain, palpitations, abdominal pain, nausea, fatigue, headaches and muscle pain. They suggested that in some individuals, COVID-19 could lead to the activation of mast cells which release histamine in response to the viral infection. As a consequence, it has been reported that a low-histamine diet is helpful in alleviating long Covid symptoms. However, the diet is very restrictive and can lead to nutritional deficiencies including vitamin B and vitamin C.
Conclusion:
Overall, if you are histamine intolerant, we recommend you embracing a low-histamine diet based on the consumption of fresh products and the elimination of fermented ingredients. The diet has shown to be helpful in minimising the symptoms of histamine intolerance such as itching, sneezing, headaches, joint pain, and nausea. Furthermore, there is evidence that indicates a positive relationship between the diet and long Covid symptoms. However, more research is needed.
References:
https://www.bbcgoodfood.com/howto/guide/what-low-histamine-diet
https://theceliacmd.com/the-low-histamine-diet-what-is-it-and-does-it-work/
https://www.medicalnewstoday.com/articles/low-histamine-diet#foods-to-avoid
https://www.cleaneatingkitchen.com/getting-started-low-histamine-diet/
https://www.bda.uk.com/resource/caution-advised-with-low-histamine-diets-for-long-covid.html
https://www.allergyuk.org/resources/response-to-long-covid-mcas-and-low-histamine-diet/
https://www.plymouth.ac.uk/uploads/production/document/path/20/20047/COVID_Histamine__1___2_.pdf
https://www.buckshealthcare.nhs.uk/wp-content/uploads/2021/10/Nutrition-and-Long-COVID.pdf
https://pubmed.ncbi.nlm.nih.gov/33919293/
https://pubmed.ncbi.nlm.nih.gov/34209583/