Photo: Unsplash/Diana Polekhina
If you're a hayfever or allergy sufferer, you're probably familiar with the effect of histamine: itchy eyes, runny nose, sneezing or itchy skin. But histamine can also have other impacts on the body, and it's something that's becoming the focus of more attention.
Search 'histamine intolerance' online, and you'll likely find alternative health practitioners offering solutions to this problem. There are also influencers on social media talking about it. You may find much of the information confusing and conflicting. So, what's all this about histamine - and could it be causing your health problems?
What is histamine?
Histamine is in all our bodies; it's a type of amine; a signalling molecule produced by cells in the immune system called mast cells and basophils. It has lots of useful roles; it's responsible for regulating many bodily functions including the release of stomach acid and body temperature.
"Histamines are all over the place all the time, and in most cases it's completely harmless and it's actually probably quite a good thing," specialist allergy dietitian Anna Richards says.
Another of histamine's roles is to act like an alarm, triggering a response when the body detects potential threats from things like allergens. The release of histamine sets off a series of responses, meant to recruit the immune system and help deal with the potential danger. Again, a good thing.
What does histamine do in an allergic reaction?
When histamine is not such a good thing is in an allergic reaction. Just like a home alarm system that might be a bit too sensitive, the body's histamine response can sometimes overreact. That's when we experience allergy symptoms like itching, sneezing or swelling. Histamine can also cause gastrointestinal symptoms like abdominal pain, bloating, nausea, vomiting, constipation and diarrhoea, and other symptoms like headaches and fatigue.
And what is histamine intolerance?
Histamine intolerance is different to an allergic reaction. It's not so much an intolerance, but rather an overload of histamine that the body can't cope with, usually from food and drink. Lots of foods naturally contain histamine, and other foods are histamine releasing, meaning they trigger the release of histamine by the body.
Tomato and aubergine are both naturally high in histamines. Photo: Unsplash
"Some people have a different threshold of tolerance [to histamine]," says Richards.
"So, it's not being processed efficiently. And if you are atopic - you have the eczema, asthma, hay fever genetic makeup - then you are just more sensitive to a load of these chemicals."
Other aspects of our health can play a role here, too.
"If you are sensitive anyway, and these things happen to cause you to react, it's going to be a dose and frequency situation", says Richards. "And if you are sensitive… then things like stress, health and hormones will all reduce what you're likely to tolerate. That's why it will pop out of the woodwork in menopause."
She explains that menopause - a time the "hormones are flinging around" can also be a really stressful time. Also worth understanding: the most common cause of spontaneous urticaria (itching with no obvious cause) in children is ill health. "And the most common cause in adults is actually stress."
What's the deal with histamine and food?
There are some foods that contain histamine, and other foods that can cause the body to release histamine when they're ingested.
"Histamine is just part of nature", says Richards.
"We find amines in two places, basically. Either they are naturally occurring; associated with things that have those big umami flavours. It's really high in things like mushroom and tomato and aubergine and things like that. But it also occurs in fermented food and protein food as it starts to break down and degrade. So fresh milk doesn't have any; stinky blue cheese has heaps. Fresh soybean doesn't have any; soy sauce has heaps. Fresh cabbage doesn't have any; sauerkraut has heaps."
People might be fine, for example, if their yoghurt is fresh and eaten quickly. But if the yoghurt gets pushed to the back of the fridge for 10 days and then surfaces again, they may have problems, Richards says.
Richards will often ask people about the alcohol they drink, since histamine is in most alcoholic drinks except for gin, vodka and whiskey.
"When someone comes to me and says, I can't drink red wine [but] I can do gin, vodka and whiskey, then my radar comes up."
How do I know if this is my problem?
If you think you might have a problem with histamine, don't start yourself on an elimination diet. First, see your doctor and eliminate other causes for your symptoms. Serious conditions like Crohn's disease, coeliac disease, ulcerative colitis and bowel cancer need to be eliminated via appropriate testing.
Histamine is in most alcoholic drinks except for gin, vodka and whiskey. Photo: Unsplash
Then, seeing a dietitian who's skilled in food chemical sensitivity can be useful.
Richards will often treat gastrointestinal symptoms first by investigating the possibility of IBS, which can very often be relieved by a low-FODMAP diet.
If symptoms haven't resolved, the next step could be looking at amines. Richards usually focuses on the most concentrated sources of amines in the diet: things like fermented foods, alcohol, avocados, aged cheeses, dried fruit, mushrooms, processed meats and canned fish. From there, it's a process of figuring out the foods that cause problems, and the levels of tolerance of those foods. It's very unlikely you'd need to completely eliminate a food.
What's the treatment?
Long term, treatment usually involves a diet that's not too heavy on the triggering foods. And there's no harm, Richards says, in taking antihistamines regularly, or just when you feel you need them. She also stresses that overall health impacts the histamine response.
"This probably won't be forever. When stress, health and hormones improve, your tolerance will typically improve too."
* Niki Bezzant is a writer, speaker, journalist and author focusing on health, wellbeing and science.