Hay fever, allergy & the microbiome
Do you see the start of Spring and Summer as the time to invest in tissues? NHS figures suggest around a fifth of the population suffers with hay fever – but that rises to a staggering 37 per cent of teenagers. Dr Jean Emberlin of Pollen UK suggests incidence could double by 2050. The length of the pollen season may also extend under the influence of climate change, which could also enable newer varieties of plants to add their pollen to the mix.
So along with tissues, a pack of Antihistamines becomes part of the weekly shopping list, though some people are starting to try natural alternatives like Capsicum. Using ionisers at home that purify the air can also help, even changing your clothes once you return home, or showering and washing your hair to remove pollen clinging to your person when the air is heavily polluted, but what a nuisance! and none of this addresses the ‘why’. Why do some people react, and some remain blissfully un-reactive?
Scientists have discovered why hay fever is more common amongst city and urban dwellers; city air includes a cocktail of pollutants and exhaust fumes that alters the molecular composition of pollen, making it more allergenic. This may support the theory that pollution is the initiating trigger of local inflammation in the respiratory airways, laying the foundation for increased sensitivity to things which should be benign and innocuous like pollen.
As individuals we can do little to control air quality or avoid environmental pollution, unless of course you’re self-employed, hibernating indoors in an air-purified bubble. For most, the advice to ‘stay indoors’ is frankly ludicrous so symptom management with anti-histamines or anti-inflammatory Corticosteroids is the only option to keep on with the day job. It’s also worth adopting an anti-inflammatory diet (see below), but let’s first look upstream at just why some immune systems become hyper-reactive, while others manage to remain tolerant.
The ‘hygiene hypothesis’ suggests fewer infections during childhood, and less exposure to bacteria generally – in an increasingly hygienic world – means the normal development of ‘immune tolerance’ goes awry. Bacteria definitely lie at the heart of the issue. They have been around since the beginning of time, involved in the evolution of so many of life’s processes, including us, and studies of children who are subjected to a more diverse range of bacteria growing up, are shown to be less prone to asthma and allergy. In a nutshell, their immune systems are more ‘tolerant’.
Immune tolerance actually starts within the gut, where 70% of the body’s immune cells reside. Mum passes on an ‘immune starter pack’ of bacteria via the placenta during her pregnancy and then also via a vaginal birth. This provides to the infant gut exactly what is needed to start the education of their immature immune system, primarily what should be tolerated and what should be viewed as ‘foreign’. Antibodies and more beneficial bacteria arrives via breast-feeding to continue the process. This is a crucial developmental period for the young immune system, so those born by C-section, who were not breast-fed, maybe grew up without pets, were not allowed to play outside in the dirt, and had multiple courses of antibiotics, go on to have guts with very different microflora, with less of the beneficial species dominating, species that might have conferred greater immune toleration. Instead their microbiota induce a higher risk of inflammatory (immune hyper-reactive) atopic conditions, like asthma, eczema and hay-fever.
The recent emergence of DNA-based techniques in stool testing has revealed the full extent of the human gut’s bacterial population; they outnumber the sum of all our cells, by an order of 10 to 1. Our skin and lungs also have a microbiome of their own and it’s not too outlandish a concept to view our physical bodies as mere packaging for the bacteria. They predate the evolution of our species but clearly identified us as a viable niche habitat, we are in effect their ecosystem. By assisting our digestive processes, synthesising vitamins for us, and training our immune tolerance, it’s clearly in their interest to keep us healthy.
As adults, we unfortunately inflict plenty of challenges to our gut microbiome, (over and above antibiotic use), through poor dietary choices. The beneficial microbes simply thrive on vegetables, another reason why ‘5 a day’ is such good advice, and frankly, 6, 7, or 8 portions is even better. Of course earlier generations preserved many of their foods through fermentation processes that left the food simply teeming with beneficial enzymes and bacteria. Today, some cultures (excuse the pun) still eat soured milk turned into unpasteurised cheese, live yoghurts and vegetables fermented in brine, these foods contain a life-force that our guts need, and bestow a diversity of bacteria that science has shown is associated with good health.
If fermented foods are a step too far for you, bacterial diversity – and with it immune tolerance – can be supported by eating many more vegetables, and including a high quality multi-strain probiotic supplement. A study in 2014 reported that hay fever sufferers given a lactobacilli probiotic for 5 weeks saw significant improvement in quality of life, in particular a reduction in runny eyes. Improvements experienced by those taking the probiotic alongside anti-histamines were more significant than those taking an antihistamine alone.
Taking probiotic supplements however should not be viewed like ‘a pill for an ill’, with the power to ‘cure’ hay fever. Food choices are really important because of how they improve the gut as a habitat for the bacteria. Otherwise you may as well be throwing seeds on barren ground. Throw unsuitable sugary foods and drinks, alcohol, antibiotics and all manner of processed food in to your gut and your gift of probiotics will not likely hang around for long.
Dietary advice to manage hay fever and nourish a healthy microbiome:
- Eat vegetables – and lots of them! – that’s what gut bacteria need, but onions and garlic are particularly useful because they contain a natural antihistamine called quercitin, a flavenoid with anti-inflammatory properties.
- Locally produced honey – immunologists suggest that eating tiny particles of the very allergen that’s causing your hay fever can help to reduce sensitivity, but you need to eat around a tablespoon of it at least three times a day. Look out for a producer at your local farmer’s market .
- Lemon grass or Cammomile tea may help both as decongestant and antihistamine.
- Oily fish like salmon, mackerel and sardines contain anti-inflammatory omega-3 fatty acids, and studies show this may reduce the prevalence of allergic rhinitis.
- Vitamin C also helps the body break down histamine so eat a portion of fresh fruit twice a day.
1 Bellanger AP et al., (2012) Reactions of airway epithelial cells to birch pollen grains previously exposed to in situ atmospheric Pb concentrations: a preliminary assay of allergenicity. Biol Trace Elem Res. 150(1-3):391-5.
2 Kelly D et al., (2007) Importance of microbial colonization of the gut in early life to the development of immunity. Nutrigenomics 622(1-2):58-69
4 Costa DJ et al., (2014) Efficacy and safety of the probiotic Lactobacillus paracasei LP-33 in allergic rhinitis: a double-blind, randomized, placebo-controlled trial (GA2LEN Study). European Journal of Clinical Nutrition 68(5):602-7
5 Karuppagounder V et al., (2016) Molecular targets of quercetin with anti-inflammatory properties in atopic dermatitis. Drug Discov Today. pii: S1359-6446(16)30037-X.