The 9 most common food allergies and how to deal with them
Being allergic to certain food can be debilitating at the best of times and deadly at the worst.
According to a new report from the Food Standards Agency, around 30 per cent of adults report having adverse reactions when eating some foods. However, only around six per cent (around 2.4 million people in the UK) were found to have a clinically diagnosable allergy.
“Even when food allergies seem mild, they can turn life-threatening at any moment,” says Dr Helen Evans-Howells, an NHS GP (known online as Dr Helen Allergy) who has devoted her career to allergy medicine since the birth of her son, who was allergic to milk as a baby and then developed a nut allergy. “Even if you’ve only ever had hives from eating sesame, for example, you could go into anaphylaxis the next time. Around 50 per cent of deaths from anaphylaxis are in people who’d been told their allergies were mild.”
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What are food allergies?
A food allergy is an overreaction by the body’s immune system to proteins found in food.
Immunoglobulin-E (IgE) is the particular immune cell responsible for causing a reaction. It’s a part of the immune system designed to fight parasitic infections. The body fights parasites by vomiting them up, sneezing them out, or clearing the eyes by watering.
“If you’re allergic to peanuts then when you eat a peanut, an IgE cell is shaped to recognise its chemical composition,” says Dr Evans-Howells, who is trustee and chair of the clinical and scientific panel for Anaphylaxis UK. “It binds to that peanut then attaches to a mast cell which contains all the chemicals that control an allergic reaction, like histamine. These chemicals are released, creating a cascade of responses.”
How do food allergies affect the body?
The most severe response is anaphylaxis – an extreme reaction by the immune system to food – which can, in rare cases, lead to death.
The signs of anaphylaxis are:
The airways becoming constricted
Coughing
Voice changes
Tongue swelling
Breathing difficulties
Dizziness, paleness, collapse
During anaphylaxis, “histamine causes the blood vessels to dilate, lowering blood pressure,” says Professor Stephen Till, a consultant allergist with a practice at HCA Healthcare UK at The Shard. “It also causes bronchial tubes in the lungs to constrict, so it becomes more difficult to breathe.”
Dr Evans-Howells says: “Anaphylaxis is sadly very common and rates of it have risen hugely, but thankfully the rates of death have reduced slightly.”
“Anaphylaxis can be self-limiting [resolve itself without treatment]. The body produces adrenaline which reverses the effects of histamine on the blood vessels. But you can’t rely on it to naturally resolve itself.”
How should you treat food allergies?
People with severe allergies are given adrenaline auto-injectors (commonly known as Epi-Pens or Jext pens) which allow them to give themselves a shot of adrenaline which should help stop the allergic response. Help should always be sought if this is given.
“You should use adrenaline as soon as you see a sign of anaphylaxis,” says Dr Evans-Howells. “If it’s just hives, swelling without any airway issues, one spell of vomiting, diarrhoea or a runny nose, then use antihistamines to treat those symptoms,” she says.
“Antihistamines won’t stop anaphylaxis, they only stop the reactions which is why it’s vital to use the adrenaline as soon as you get more serious responses.”
What is the difference between an allergy and an intolerance?
People sometimes confuse ‘allergy’ with ‘intolerance’.
“An allergy involves a very specific part of your immune system reacting to something it shouldn’t react to. An intolerance is something which causes symptoms, but not of an immune nature,” says Professor Till. “Some people might feel bloated, have wind and diarrhoea when they drink milk - that’s a common manifestation of lactose intolerance, but it’s not a milk allergy. It’s that their body can’t digest lactose well.
Generally, intolerance reactions are less severe than allergic reactions. “Allergies can cause medical emergencies. That’s not often the case with intolerances.”
At what age can food allergies appear?
Milk and egg allergies are more common in infants but they usually grow out of them by three or four years old. Tree nut and peanut allergies can come on in children but tend to last into adulthood. Fish and shellfish allergies can start at any time.
“The children who are more allergic in childhood tend to be those whose allergies persist into adulthood,” explains Professor Till.
If you were allergic to milk or eggs as a child and have avoided them ever since, it may be worth visiting an allergy specialist for another diagnosis. However, “things like peanut, tree nut, sesame, fish and shellfish allergies – as long as the original diagnosis was accurately made – tend to stick around into adulthood,” says Professor Till.
Are there any cures for food allergies?
There are no current cures for food allergies. However, treatments and new therapies are becoming more widely available.
A £2.5 million trial at the University of Southampton, funded by the Natasha Allergy Research Foundation found that food immunotherapy works to help increase the amount of an allergen a person can consume before they have a reaction. But it isn’t a cure.
Dr Evans-Howells’ private allergy practice in Poole, Dorset, became the UK’s first community clinic, outside of London, to offer food immunotherapy, a process by which mostly children are given minuscule amounts of the food they’re allergic to in order to decrease their sensitivity to it.
“You give someone a tiny amount of the thing they’re allergic to – in this case nuts – every day for a number of weeks, then you gradually add a bit more,” says Dr Evans-Howells. “You’re basically trying to sneak that allergen past their immune system which builds up how much they can have before a reaction is triggered.”
Immunotherapy has been widely used in the US and Canada for a decade, but it is relatively new to the UK. “It’s time-consuming because fortnightly appointments are needed and you need to have good supervision of patients afterwards – it’s a four-hour appointment,” says Dr Evans-Howells.
The trouble is that food immunotherapy currently only seems to work in children. “There’s some evidence that it works in adults, but it’s less successful,” explains Dr Evans-Howells. “Our immune systems are less malleable than children’s so adult studies tend to have less significant results and more side-effects.”
However, while immunotherapy does work, Dr Evans-Howells cautions that it must not be attempted at home. “With peanut immunotherapy the first dose is 0.5mg – for context, one peanut is 300mg,” she says. “It’s a tiny, tiny amount. In the wrong hands, this therapy could kill someone. Some people do try it but they may have tragic consequences. It just isn’t worth it.”
Another trial looked at a drug called Omalizumab, which seemed to reduce allergic reactions for as long as the drug was being taken, but the reactions returned once patients stopped. However, some trials are ongoing to see whether Omalizumab could be combined with food immunotherapy for adults and children.
These are the nine most common food allergies:
“Milk is the biggest cause of allergic deaths in children in the last 10 years,” says Dr Evans-Howells. “There’s a problem with both overdiagnosis and underdiagnosis with milk. Often the words ‘allergy’ and ‘intolerance’ are conflated which leads people to dismiss milk allergies. But milk can absolutely cause anaphylaxis, and does.”
Milk allergies are thought to affect around two to three per cent of babies and toddlers, though 90 per cent grow out of the allergy by the time they’re around three.
If your child has a milk allergy, it is important to read the labels of products carefully. Even non-dairy and milk-free products sometimes contain the milk proteins which can cause anaphylaxis.
Extensively hydrolysed milks are created for infants. Whilst these still contain milk proteins, the protein chain has been broken down so well that up to 90 per cent of infants will tolerate them without issue. If a child does react to these, amino acid formulas can be prescribed; which would have no milk protein contained.
“For those over 12 months, if tolerated, we often recommend soya or oat milks as these are high in protein which is good for growth,” explains Dr Evans-Howells. “It is important to make sure these milks are fortified with calcium and vitamin D. Pea protein milks can also be a useful alternative as long as the child can tolerate peas. Coconut and nut milks tend to have lower protein content so are less suitable for most.
“Children under six months of age can have these milks in their diet to mix with cereals etc. but their main drink under 12 months should either be breast milk or a prescription formula.
Prescription formulas are available for those with a milk allergy.”
The second most common allergy in children, but another which the majority of sufferers (68 per cent) grow out of by the time they’re adults.
“In contrast to milk, eggs seem to be something that doesn’t very commonly cause death,” Dr Evans-Howells says. “Although, I have seen people go into intensive care after a reaction to eggs.”
Eggs are a tricky allergy because a person can be allergic to the white or the yolk or both because the proteins which make them up are slightly different. Those same proteins can become denatured (changing shape) if cooked which can, in some cases, prevent allergic reactions. A Portuguese study found that 67 per cent of children with an egg allergy could eat muffins made with eggs.
“Heating eggs or milk changes the allergenicity of these proteins, meaning that for some, allergic symptoms are not triggered,” adds Dr Evans-Howells. “If a child can eat baked eggs (or baked milk), then they should do so, at least three times a week. This will help them to grow out of their allergy quicker, but you should always take medical advice about whether this is suitable for your child.”
“Soy [reaction] is one I see in my clinic quite frequently, perhaps because it’s not such an obvious thing to avoid and requires careful reading of labels to check,” says Dr Evans-Howells. Many products which contain soy are obvious: edamame, miso, soy sauce, soy-based flour, soy milk, tempeh, teriyaki sauce and tofu. However, others are less obvious: it is sometimes used to bulk out cereals and processed meat, make ice cream and yoghurts smoother, and add flavour to canned meat, fish and soup.
Around 70 per cent of children grow out of a soy allergy, and it affects 0.5 per cent of infants and babies under three.
“Peanuts are often considered the most severe allergy, but that’s not always true,” says Dr Evans-Howells. “That came about because a study found that 75 per cent of people with a peanut allergy would eventually go into anaphylaxis if they ate enough, which was higher than other allergens.”
Only 20 per cent of children grow out of a peanut allergy, making it the second most common allergy for adults.
Including almonds, cashews, walnuts, pistachios, pecans (pine nuts are not a nut, neither are coconuts!), Brazil nuts and macadamia nuts.
A tree nut allergy is also fairly commonly found in adults, with only 10 per cent of children growing out of it after becoming adults. It is thought to affect up to three per cent of people worldwide.
While a tree nut allergy isn’t the same as a peanut allergy (peanuts are a legume), around 40 per cent of people with peanut allergies also have a tree nut allergy.
Nut oils, nut butter and nut milks should also be avoided.
The good news is that oral immunotherapy (as mentioned above, please link back here) has already proven effective in helping reduce the sensitivity of people with nut allergies.
These treatments are also now available for other foods.
Well-known in Britain thanks to the tragic case of 15-year-old Natasha Ednan-Laperouse who died in 2016 after eating a Pret sandwich which wasn’t labelled correctly. Sesame allergies had often been thought of as less severe. “It’s not true though - any allergy can be as severe as any other at any time,” says Dr Evans-Howells.
Sesame is also a less well-known allergy because in America it wasn’t declared an allergen until as recently as 2021. It was only from 2023 that sesame allergy labelling became mandatory in the US so check dates on packaging, because any product released before this date doesn’t need to disclose the presence of sesame. Around 17 per cent of children with peanut or tree nut allergies are also allergic to sesame, so often it has been forgotten in favour of those.
Fish is an allergy which has the rare distinction of tending to show up in adults rather than children. Around 40 per cent of people with a fish allergy report it only arriving after they were 16.
“One thing particular to fish, or at least much more common, is that the fish proteins can be aerosolised by cooking or frying,” says Professor Till. “That means people with fish allergies may get asthma or respiratory symptoms from being around cooked fish.”
Often confused with a gluten intolerance or coeliac disease, a wheat allergy is slightly different in that those who suffer from it can eat gluten from other sources and grains such as barley, rye and spelt. It is just the wheat which can cause symptoms and potentially anaphylaxis.
This is caused by proteins found in shrimp, prawns, lobsters, crabs, squid, oysters and scallops, and generally people find they are allergic to one “family” of shellfish such as crustaceans.
An allergy to fish doesn’t necessarily mean you’ll have an allergy to shellfish as well. “Individuals with shellfish or fish allergies are not necessarily allergic to all as the proteins triggering the reaction are different,” says Dr Evans-Howells. “You can be allergic to crustaceans (eg. prawn, lobster, crab) but not molluscs (eg. squid and oysters). Or, you can be allergic to shellfish but not fish, or, you can be allergic to white fish but not salmon/tuna – and vice versa. It is therefore vital to have a full assessment to ensure you know exactly what triggers your allergic reaction.”
Some research shows that symptoms of an allergic reaction (raised red rash, tingling or itchy mouth, swelling in the lips and face, stomach pain or vomiting) to shellfish come on faster than other allergens, which might be why this is thought to be a more “dangerous” allergy to have.
“People can truly be allergic to oysters and other shellfish, but there can also be reactions which mimic allergies but are due to high histamine levels in shellfish that isn’t fresh,” explains Dr Evans-Howells. “Allergies to shellfish can be outgrown, but beyond that there are no treatment options in the UK as yet. Unfortunately, there’s nothing else to be done with a shellfish allergy, it won’t get better if you cook them or anything – if you’re allergic any form of them will trigger a reaction.”
“Prawns is an interesting allergy as it can appear later in life,” says Professor Till. “I’ve had patients in their 70s develop anaphylactic reactions to prawns after eating them their whole life.”
