The secret to beating hay fever could lie in your gut
The sun is finally out, and hay-fever season is fast approaching. Any minute now, teens will tackle their exams with red eyes, and adults will find their romantic country breaks wrecked by unsexy sneezing. We will trudge in our millions to the chemist, where we will buy antihistamines that make us drowsy and steroid nose sprays that provide only momentary relief.
“Twenty-five per cent of UK adults get hay fever, and a good 15-20 per cent of those won’t get adequate relief just by taking antihistamines and using nasal sprays,” says Prof Adam Fox, consultant paediatric allergist at Guy’s and St Thomas’ hospitals. “Hay fever affects performance, productivity and quality of life. For the people who suffer badly, it’s no joke.”
Hay fever is caused by the inhalation of grass or tree pollen granules, which are then processed by the immune system. If you have a genetic predisposition to developing an allergy to these plants, then there’s a risk that you will develop an inappropriate response and release a chemical called histamine.
“Classic symptoms will be itchiness, redness, inflammation and sneezing,” says Prof Fox. “Other chemicals are released, too, which cause chronic symptoms like nasal congestion.”
There is no cure for allergies, which are notoriously difficult to treat. But a glimmer of hope may finally be on the horizon. A growing body of studies suggest that there might be an alternative method for tackling our symptoms – through our diet, and dietary supplements.
In January, the journal Nature Microbiology published the results of a study that compared the nasal microbiomes of 55 hay-fever-plagued adults with those of 205 healthy volunteers. It found that the hay-fever sufferers had a much narrower range of bacteria in their noses, but also 17-times more of one particular kind: Streptococcus salivarius. This, they found, can drive the inflammation that troubles hay-fever sufferers.
“For some time now, we’ve known that the gut microbiome of food-allergic people is different from that of those who don’t have those allergies,” says Prof Fox. “We now have similar findings when it comes to hay fever and the bacteria that colonise our nasal passages. People with diverse bacteria in their nasal lining seem to be at a lower risk of hay fever. Those with less diverse bacteria seem to be at a higher risk.”
So, is there anything we can do to feed these friendly, sneeze-busting bacteria?
Eat the sniffles away
Although allergies are genetic conditions, lifestyle factors can still come into play. Shilpa Ravella is a gastroenterologist, an assistant professor of medicine at Columbia University Medical Center in the US, and author of A Silent Fire: The Story of Inflammation, Diet and Disease. “Our genes haven’t changed in the past two decades, but allergies have risen and are continuing to do so. What’s changed? Our food environment,” she says. “Food can play a very important part in calming inflammation.”
Allergies, including hay fever, are inflammatory conditions. Some meals, such as sugary or processed foods, can worsen cellular swelling.
Anti-inflammatory diets can help both to prevent and alleviate hay fever, suggests Dr Ravella. Children raised on them are less likely to develop allergies in the first place, she says, while “what you eat can certainly decrease your symptoms, too”.
An anti-inflammatory diet is composed of foods that fight the condition: the Mediterranean diet – which contains fresh fruits and vegetables, whole grains, fish, and olive oil – is a classic example.
Onions, especially red ones, are not only anti-inflammatory, but also contain the polyphenol quercetin, which acts as an antihistamine. Apples are also a good source.
Meanwhile, omega-3-rich foods such as walnuts, flaxseed, mackerel and sardines are helpful: “Not only are these foods anti-inflammatory, they also help the resolution of inflammation,” says Dr Ravella. “In other words, they both dampen it and help in the process of reversing it.”
How we prepare these ingredients is also important. “From an anti-inflammatory standpoint, most people need to be eating both raw and cooked foods,” says Dr Ravella. “If you simmer tomatoes in the traditional Mediterranean style, for example, you drastically increase the content of lycopene, which is an antioxidant that decreases allergic responses. Gentler cooking methods, such as steaming or poaching, are better, both in terms of anti-inflammatory potential and nutrient content, says Dr Ravella.
“Vitamin C also acts as a natural antihistamine, which can be found in foods such as citrus fruits, broccoli, peppers, chilli, kale and rocket,” says Eve Kalinik, nutritional therapist and author of Happy Gut, Happy Mind. It is, however, easily destroyed by heat and light, “so trying to cook these as little as possible will help to retain more potency”.
Fermented foods, such as live yoghurt, kimchi, kefir and sauerkraut, are linked to lower inflammation and higher diversity of your gut bacteria. But, sadly, eating honey made by local bees – occasionally touted as a cure for hay fever – is “an urban myth”, says Prof Fox. “There’s no science behind it at all.” Prof Fox thinks that antihistamines and nasal seats are still the best treatments to try first.
It’s never too early to start an anti-hay-fever diet. “You need to give the bacteria time to respond, and your immune system time to calm down,” says Simon Gaisford, professor of pharmaceutics at UCL. “Think of it like getting beach-body-ready.”
Reach for a liquid probiotic
According to Prof Gaisford, the science of probiotics and allergies is still in its infancy, but shows great promise – including in the area of treating allergies. In 2022, a study led by scientists at the National Institute of Integrative Medicine, in Melbourne, Australia, gave the probiotic formula NC-Seasonal-Biotic to hay-fever sufferers. They found that it significantly reduced symptoms, compared with a placebo group. After 10 to 12 weeks, the volunteers’ noses ran less and their eyes itched less. They even slept better and felt less irritable.
“There are thousands of different types of bacteria in your gut,” says Prof Gaisford. “They’re living things, so just like us they eat food and produce waste. They take the Shredded Wheat you eat for breakfast and turn it into myriad different compounds that we call metabolites. Different bacteria produce different compounds, some good for you, others bad.”
Some of those beneficial compounds will be absorbed into the bloodstream, Prof Gaisford explains, where they circulate to, and exert a positive influence over, other parts of the body, including the nose. In a related mechanism, the immune system interacts with that bacteria, so if you take an oral probiotic, you rebalance some of the bacteria in your gut, and your immune system starts to calm down.
And as hay-fever season approaches, you might reap the benefits of this science. “Hay fever is an overreaction of your immune system to pollen,” says Prof Gaisford. “If your immune system is already sensitive because of irritation in your gut, then it’s highly reactive. If it’s calm, it stands a better chance of reacting healthily to pollen.”
Experts recommend liquid probiotics such as Symprove and BetterVits Probiotic Complex, rather than the powdered varieties. “It’s a challenge for a powdered product to deliver live bacteria into the gut,” says Prof Gaisford.