Do you dread the onset of allergy season, knowing full well that you’ll be reaching for an anti-histamine every day? Do you suffer from facial flushing and headaches after drinking wine, or experience unusual abdominal discomfort and bloating? If these symptoms ring a bell, you may be struggling with histamine intolerance. In my experience as a clinical nutritionist, I’ve observed an increasing prevalence of histamine intolerance in my client population. In this two-part blog series, I’ll explain the science behind histamine, the underlying causes of histamine intolerance, and how nutritional and lifestyle interventions can balance histamine activity and help you restore your health!
What is Histamine Intolerance?
Histamine is a compound released by immune cells in response to injury and allergic and inflammatory stimuli. It plays multiple essential roles in human physiology:
Histamine functions as a neurotransmitter, sending signals to your brain, communicating wakefulness and attention. (1)
Histamine stimulates the release of gastric acid from parietal cells of the stomach, a critical step in the digestive process. (2)
Histamine is involved in the inflammatory response after injury, including the contraction of smooth muscle and the dilation of blood vessels. These processes recruit immune molecules into the site of injury to repair damaged, inflamed tissues.
While histamine plays several crucial roles in the body, it can cause problems in excess. When your body produces (or consumes) excess histamine, or fails to break down circulating histamine, the pro-inflammatory and vasodilating effects of this chemical can cause significant health problems. Some of the symptoms of histamine intolerance include:
Neurological: Headaches, vertigo, impaired body temperature regulation, brain fog, fatigue. Interesting new research suggests that histamine and allergic inflammation may play a role in ADHD and autism spectrum disorders due to histamine’s effects on neurological function. In a preclinical model, a histamine receptor antagonist was found to attenuate autistic behaviors in juvenile rodents; I’d be interested to see if a low-histamine diet or anti-histamine nutraceuticals could have a similar effect! (3, 4, 5)
Cardiovascular: Arrhythmias, tachycardia, hypertension/hypotension (high or low blood pressure)
Respiratory: Bronchoconstriction, nasal congestion, sinus issues
Gastrointestinal: Abdominal pain, bloating, diarrhea, flatulence, nausea, vomiting, motion sickness
Food and chemical sensitivities
Dermatological: Flushing, itching, hives
Female reproductive system: Dysmenorrhea, irregular menstrual cycle
As you can see, many of the symptoms of histamine intolerance overlap with other conditions, such as IBS and environmental allergies. Many clinicians mistake histamine intolerance for other conditions, leading to continued suffering on the part of the patient/client.
Diagnosis of Histamine Intolerance
The wide range of symptoms triggered by histamine intolerance makes it quite challenging to diagnose, at least if you are relying on biomarkers. You can obtain a measurement of whole blood histamine from labs such as Quest and LabCorp, but this measurement is simply a snapshot of your histamine level at one point in time. Many of my clients who have histamine intolerance received "normal" whole blood histamine results. It is also possible to test for levels of diamine oxidase, an enzyme that breaks down histamine in the gut; however, this marker also frequently comes back “normal,” even in the most histamine-sensitive people.
If we can’t use biomarkers to detect histamine intolerance, what are our alternatives? I have found that a trial of a low-histamine diet is the best way to determine whether a client is suffering from histamine intolerance. On a low-histamine diet, you'll avoid histamine-containing and histamine-liberating foods for at least six weeks while tracking changes in your symptoms. If you feel better on the low-histamine diet, then you are likely histamine intolerant. It is crucial to commit to a low-histamine diet for at least six weeks because delayed reactions are common in histamine intolerance, and it may take some time to correlate changes in symptoms with dietary changes.
Underlying Causes of Histamine Intolerance
While histamine intolerance is a distinct condition, it is actually a reflection of underlying disturbances in your body that are either increasing histamine production or impairing your ability to degrade histamine.
Leaky Gut and SIBO
Two of the most important causes of histamine intolerance are leaky gut and small intestinal bacterial overgrowth (SIBO). Leaky gut, referred to in the scientific literature as “increased intestinal permeability,” occurs when the tight junction proteins holding adjacent intestinal cells together become damaged, resulting in "holes" or "cracks" between the cells. These intracellular spaces allow undigested food proteins and bacterial byproducts to leak from the intestinal lumen into the systemic circulation, provoking in the inflammatory response. The resulting inflammation triggers the production of histamine, causing your “histamine bucket” to overflow and resulting in histamine intolerance.
SIBO is defined as an excess of bacteria in the small intestine. There are both histamine-producing and histamine-degrading species of bacteria in the gut; when the small intestine is overflowing with bacteria, histamine-producing strains may outnumber histamine-degrading strains, resulting in a high endogenous level of histamine. The inflammation triggered by SIBO also causes histamine production by your own body. Correcting leaky gut and/or SIBO is essential for getting histamine intolerance under control.
If you’ve read any of the trending health news lately, you’ve probably heard that fermented foods and probiotics are great for your gut health; however, this statement is only partially true if you have histamine intolerance! Histamine-sensitive people need to avoid histamine-producing strains of bacteria, which are found in fermented foods and many commercial strains of probiotics. Histamine-producing bacteria that you'll want to avoid include most species of Lactobacilli, including Lactobacillus casei, L. reuteri, and L. bulgaricus. I’ll talk more about avoiding fermented foods when we dive into the low-histamine diet in part two of this blog series.
On the other hand, histamine-degrading bacteria include Bifidobacterium infantis, Bifidobacterium longum, and Lactobacillus plantarum. Streptococcus thermophiles, Lactobacillus rhamnosus, and soil-based microorganisms may be either histamine-degrading or neutral and tend to be well-tolerated by those with histamine intolerance.
Lyme Disease and Other Chronic Infections
Histamine is produced by the immune system when it needs to target and eliminate pathogens. Also, specific pathogens trigger the activity of mast cells, immune cells that liberate histamine and other inflammatory molecules upon provocation. Borrelia burgdorferi, the bacterium that causes Lyme disease, is known to trigger mast cells; I suspect this is why many of my clients with chronic Lyme disease also have histamine intolerance. (6) The immune system also recruits mast cells to combat Mycoplasma, a common Lyme coinfection, potentially resulting in “histamine overload.” (7) I suspect that these two infections are just the tip of the iceberg when it comes to the types of pathogens that trigger histamine intolerance.
Some pathogenic microorganisms also block methylation, an essential biochemical pathway for breaking down and removing histamine from the body.
In my personal experience, toxic mold exposure was a significant trigger of histamine intolerance. Mycotoxins, the toxic compounds produced by molds, trigger the release of pro-inflammatory cytokines from immune cells, including the release of histamine from mast cells. (8) If you struggle with histamine intolerance, getting yourself out of the mold-contaminated environment that is triggering chronic inflammation is essential. Once you’ve removed yourself from the harmful environment, I recommend commencing my triphasic low-histamine/low-mold/dysbiosis diet while also focusing on nutraceutical and lifestyle strategies to facilitate detoxification and recovery.
A High-Histamine Diet
Consuming a diet rich in histamine-containing and histamine-liberating foods can trigger histamine intolerance in susceptible individuals. Food-based histamine is derived from the amino acid histidine. When bacteria naturally present in food metabolize histidine, they end up producing histamine. This means the most dietary sources of histamine are foods that contain bacteria, such as fermented and cured foods. Leftovers are also a common source of histamine because, after cooking and cooling, bacteria proliferate in the food and convert histidine into histamine. Some foods are histamine liberators, meaning that while they don’t contain high levels of histamine, they can trigger histamine release within the body. Following a temporary low-histamine diet can do wonders for people with histamine intolerance.
Eating foods to which you are sensitive or allergic, even if they are not histamine-containing or histamine-liberating foods, can also trigger histamine intolerance. This is why I often recommend that my histamine-sensitive clients undergo food sensitivity testing, so we can eliminate all possible dietary sources of inflammation.
Environmental allergens such as pollen, mold (discussed above), mildew, and dust mites may contribute to the development of histamine intolerance. I suspect that global warming may also be contributing to histamine intolerance by lengthening “allergy season,” forcing our immune systems to struggle with ever more potent allergens. (9)
Do you struggle with histamine intolerance? Let me know in the comments below! Stay tuned for Part 2, in which I’ll cover genetic contributors to histamine intolerance and nutrition and lifestyle strategies that can help you reduce your sensitivity and regain your health.