Three years ago, when I started researching my new book about allergies, Irritated: The Allergy Epidemic and What We Can Do About It, I assumed most allergies started in childhood, and that all adults with allergies got them when they were kids.
I’m a food and health journalist, and my daughter developed allergies as a toddler. As I became more aware of allergies and how they can impact a family, I also became obsessed with trying to work out why we are more allergic now than we have ever been. Allergies were once so rare that the word “allergy” didn’t even exist until 1906; today 21 million people in the UK have at least one allergy.
Back then (which was also before I crash-landed in perimeno-land myself), I had no idea that about 50 per cent of adult food allergies start after the age of 18, and I definitely didn’t realise that women, and particularly midlife women, are much more likely to develop a new food or environmental allergy than men.
I doubt it will surprise you to learn that since we’re talking about women’s health, the relationship between our reproductive hormones and allergies isn’t terribly well understood. Research is only just beginning to look at why, for instance, some women’s allergies get worse around ovulation or immediately before and during their period.
Women are more likely to be hospitalised with asthma just before their period, while pregnant and during menopause, and about 20 per cent of women develop new or worsening hayfever when they’re pregnant. Menopause can come with enough discomforts of its own, so it seems unfair that midlife hormonal changes can also make us more likely to develop new allergies during menopause.
We know there is a direct relationship between female sex hormones and developing allergy symptoms, and that hormones such as testosterone seem to suppress them; by adulthood, more women than men have asthma or an allergy (or both), and women are more likely to have serious symptoms and to end up in hospital because of them, too. (Aren’t we lucky?)
Hormones at play
Testosterone appears to downregulate some of the immune system’s behaviour, especially in asthma. Women do produce testosterone, but much smaller amounts than men, and our levels drop as we age, which could help explain why some of us develop more or new allergies from our 40s onwards.
At that time, oestrogen is basically on a rollercoaster, gradually reducing overall as menopause approaches, but rising and falling as it does so in unpredictable zigzags, with levels sometimes increasing more than at any other time of life before crashing precipitously.
Oestrogen is definitely connected to how we experience allergies: women with allergies will develop a bigger wheal if they are skinprick-tested for allergies on the days of their cycle when oestrogen levels peak; other studies have shown that among women with hayfever, the insides of their noses are more reactive on those days, too.
Histamine explained
Histamine is one of the main signalling chemicals involved in allergic reactions (which is why we take antihistamines to try to calm their symptoms). Oestrogen and histamine can create a feedback loop in which they each encourage levels of the other to go up. Oestrogen’s chaotic behaviour is probably why perimenopausal women are more likely to be diagnosed with histamine intolerance as well, an allergy-adjacent condition which happens when the histamine we make and the histamine we consume in food isn’t cleared out properly by the body, builds up and causes what can look and feel a lot like an allergic reaction, as well as systemic symptoms such as headaches.
Some women find that taking HRT or the contraceptive pill makes their allergies worse, although for others the opposite is true. Statistically, more women get an asthma diagnosis after being prescribed HRT, which is something to look out for, and taking HRT is sometimes linked to histamine intolerance, too.
Some GPs are well-informed about all this, but if you’ve already found that your GP isn’t up-to-date on menopause management, they’re probably not going to know much about its relationship with allergies either. This healthcare gap pushes many women to spend money on home tests that do not work. There are no food intolerance blood tests at all that give accurate results – they are a scam, despite what some less well-trained nutritionists and the test makers themselves say – and no fully reliable tests for histamine intolerance either.
A warning about testing
Although they are easy to buy online, doing allergy tests without a clinician to help you read the results is risky, too, because they often give false-positive results. Inaccurate intolerance and allergy test results are really unhelpful because they encourage us to give up foods we can actually eat – paradoxically, doing that can make you more likely to develop an actual allergy to whatever food you have stopped eating.
The lack of knowledge about all this leaves many of us struggling with symptoms on our own, but if you do develop new allergies or asthma in midlife or during menopause, it’s worth asking for a referral to an allergy specialist, even if the waiting lists are long, and talking to them about whether your hormones, or any hormonal treatments you are taking, might be part of the cause.
Irritated: The Allergy Epidemic and What We Can Do About It, by Rebecca Seal, is published by Headline Home, £22
Read the full article here
