At this time of year, histamine springs to mind quite often, especially for those suffering with hay fever and seasonal allergies. While histamine is well-known for causing itching, sneezing and scratching, it can also be responsible for a host of other effects in the body. If you have digestive upsets, multiple food intolerances or migraines, histamine could be the culprit. If you are a woman of 45 who suddenly gets a headache from a glass of wine, it could also be histamine. If you started drinking bone broths because you heard they are fabulous for your gut, but suddenly got terrible brain fog and bloating, it could be histamine too! Read on to unlock the secrets of this fascinating compound and how it could be affecting your health.
What is histamine?
Histamine is a little molecule that helps our cells communicate. It is a chemical messenger. When our immune cells come into contact with some invasive pathogen, like a parasite for example, they release histamine to let a few things happen to get rid of that invader more easily.
Histamine activates the immune system, and makes blood vessels more porous to help white blood cells come through to the rescue. In short, histamine creates a localised inflammation to help the body deal with the unwanted visitor. But what happens when that unwanted visitor is just a stray bit of pine pollen, or a bit of cat hair? This is the nature of allergy, when the immune system’s radar is set a little too high and it starts shooting at things that aren’t so dangerous after all. In this case, all the great things histamine does become pesky and bothersome. The inflammation causes nasal congestion, itching, hives, watery eyes, digestive upsets and all manner of unpleasantness. What’s more, it keeps doing this for as long as the allergen is present.
Histamine reactions look and feel like:
- Skin: itchy, red, swollen
- Eyes: itchy, red, puffy/swollen, sore, watery
- Gut: Diarrhoea, cramping, bloating, pain
- Head: Headaches, migraines, brain fog, insomnia
- Nose: Sinus congestion, running itchy nose
- Hormonal: PMS, menstrual pain
- Lungs: constriction causes shortness of breath or difficulty breathing
- Blood pressure: lowered
- General: pain, swelling, itchiness, irritability
The most severe of histamine reactions is of course anaphylactic shock, when all of these happen on a massive scale and can be life-threatening. The only remedy for this is a shot of adrenaline, administered by an epipen.
What is histamine good for?
Histamine has a bad reputation. All the advertising you see for antihistamine medications would lead you to believe that this little molecule is an evil to be eradicated at all costs. As ever, this simply isn’t the whole truth. Histamine does some great things in our bodies too.
- Is essential for immune function, as outlined above
- Regulates stomach acid
- Stimulates the brain to keep us awake
- Increases libido
- Is essential for female fertility and ovulation
Histamine intolerance occurs when normal levels of histamine trigger unwanted symptoms, usually due to the body’s inability to break it down effectively. Diamine Oxidase (DAO) is the main enzyme in our bodies that breaks down histamine. Low levels of this are one of the main causes of, and indicators for, histamine intolerance. A blood test is available through practitioners for testing DAO levels. DAO works mainly outside cells, and other enzymes work inside cells to break down histamine. It’s called Histamine-N-methyl-transferase (HNMT), and can be supported by nutrients such as methionine.
What decreases DAO activity?
- Most gastro-intestinal diseases such as Inflammatory Bowel Disease, gastritis, dysbiosis, infection etc
- Many medications- the list is too large to include here! Weirdly, some antihistamines inhibit DAO. Other common medications such as antidepressants, antibiotics, and diuretics are also on the list.
- Oestrogen (more on this coming up!)
MCAS or MCAD stands for Mast Cell Activation Syndrome or Disease. It is a rare kind of chronic histamine issue, where multiple body systems can be affected. Mast cells are the immune cells which release histamine, and in MCAS, there are too many of them, and they are too active. This causes long-term inflammation in many areas. Symptoms usually start early in life and are ongoing, although stress can trigger acute flare-ups. It’s a tricky one to diagnose and more is being discovered about MCAS all the time. Other than testing for DAO, a urinary test for N-Methylhistamine (one of the things that histamine breaks down to) can help with diagnosis.
What’s the Difference Between Histamine Intolerance and an Allergy?
Good question! As both involve histamine, it’s easy to mistake histamine intolerance for an allergic reaction. The symptoms are really similar. What’s really key to understand is that a true allergic reaction will be more-or-less immediate (For more on the difference between allergies and intolerances and reactivities please read here!). There will also usually be a positive blood IgE or skin-prick test to a particular substance/s. Histamine intolerance is different, it sneaks up a bit more slowly, and will be worse depending on how much of the histamine food/s you’ve had. Or also perhaps on what time of the month it is, how much alcohol you’ve had, and other variables. You may think you have multiple food sensitivities, and this could be true, and the problem may, or may not, be histamine. The clues are in the foods that are your triggers…
Histamine & Hormones
The interplay of hormones and histamine is one that is complex and gaining increasing attention. It seems that women are more vulnerable to the effects of histamine at certain times of the menstrual cycle, specifically when oestrogen is high relative to progesterone. These times include ovulation, premenstrually, and in the years leading up to menopause known as perimenopause. There is new research outlining the role of histamine in many hormonal conditions such as endometriosis.
Oestrogen causes an increase in histamine via 3 routes:
- Directly stimulating the immune system to make more histamine
- Reducing DAO and the breakdown of histamine
- Elevated histamines trigger the ovaries to increase oestrogen, thus amplifying the effects.
High Histamine Foods
- Regular Tea, Green Tea, Coffee, Cocoa, Kombucha
- Breads with yeast (including sourdough)
- Fermented soy products: miso, soy sauce, tempeh etc
- Aged Cheeses
- Banana, Citrus fruits, Strawberry, Kiwifruit, Papaya, Pineapple, Plums, Raspberries
- All dried fruits/fermented fruit and vegetables, including pickles
- Smoked/cured/tinned fish or meat, shellfish, bone broths, sausages
- Food additives (including preservatives, colours, flavours, MSG)
- Cocoa, chocolate
- Fermented foods (kimchi, sauerkraut etc)
- Some spices (chilli, curry, cinnamon, clove, anise, nutmeg)
- Eggplant/aubergine, avocado, spinach, tomato
- Licorice & vanilla!
No two lists of histamine foods will be the same, but there are many commonalities.
If you are embarking on a low-histamine diet, you also need to factor in the following:
- Aged foods are higher in histamine, so fresh is best
- Some foods aren’t high in histamine but interfere with the breakdown of histamine
- Other foods can trigger mast cell degranulation (where the mast cells break apart and release their histamine)
- Some foods may not be high in histamine but still stimulate histamine production- dairy is a prime example
- Any food that you yourself are reactive to has the potential to increase histamine
- Alcohol is a great example of something to avoid: it triggers immune cell release of histamines and also interferes with histamine breakdown by inhibiting our friend the DAO enzyme. (Please note that histamine isn’t the only reason for reacting to alcohol though- wine can contain sulphites which commonly cause reactions, and there are multiple causes for symptoms brought on by alcohol, including poor liver clearance).
What Can I Do About It?
As ever, avoiding the triggers is the first step to wellness, but if your treatment stops there you probably won’t change anything in the long term! Avoiding reactive substances really just gives your body a break and a fighting chance to heal, creating an opportunity to do the good gut repair work that is key for overcoming histamine intolerance.
- Avoid histamine foods and those that inhibit the breakdown of histamines.
- Increase levels of nutrients that support the DAO enzyme if they are low: Vitamin B6, Vitamin C, zinc and copper (careful with copper- read here for more info on this tricky little metal!). Support histamine breakdown inside cells with methionine.
- Improve gut integrity and heal intestinal lining, encourage beneficial bacterial growth, look after your microbiome. Please note some probiotics are better than others for histamine! Bifidobacterium longum, Bifidobacterium infantis and Bifidobacterium breve may be especially beneficial where there is a histamine overload, while Lactobacillis. casei, L. delbruekii and L. bulgaricus may be best left alone.
- Balance immune reactivity and calm histamine using natural remedies and herbal/nutritional supports.
- Increase oestrogen clearance if appropriate by encouraging regular bowel function and optimal liver function.
Histamine reactions are not a life sentence. You don’t have to trip off to the GP every season for more hayfever pills. Understanding histamine and what drives it is key to getting on top of your symptoms and living a less reactive life.