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Why you might become allergic to shellfish, nuts or even bird’s nest with age

Your Gut Feeling is an ongoing series on digestive health. In this instalment, find out why some people who were perfectly fine suddenly develop food allergies later in life.

Eating is one of the greatest pleasures in life, and you might feel like your body has let you down when your digestive system starts to turn in a less-than-stellar performance as you age. What’s up with your body? In this instalment of My Gut Feeling, we look at indigestion.


You may have been enjoying har cheong gai (deep-fried prawn paste chicken) or sambal udang (prawn sambal) all your life. But recently, your body has decided to revolt by rejecting the crustacean in the most dramatic fashion – a food allergy.

READ: Is it just indigestion? Why it's harder to enjoy buffets and suppers as you get old

Just a sip of prawn noodle broth and the symptoms start popping up: Itchy hives and rashes, tingling around the mouth, swelling of the face, tongue and throat, asthma-like wheezing and breathlessness, dizziness, and even digestive symptoms like abdominal pain, vomiting and diarrhoea

In the worst situation, the offending food may even put you in a life-threatening reaction called anaphylactic shock.

(Photo: Pexels/T Nguyen)

“The symptoms of a food allergy are quite similar to other allergic reactions as they are mediated by antibodies called immunoglobulin E or histamine, and other substances released by immune cells in the gut called mast cells,” explained Dr Melvin Look, the director of PanAsia Surgery and a consultant surgeon in hospitals such as Mount Elizabeth Hospital.

We found that about half, 48 per cent, said they developed at least one new food allergy as an adult that they didn't have as a child.

“These reactions may be triggered by eating even a tiny amount of certain antigens contained in certain foods,” he said.

And it doesn’t have to be shellfish, though that is the most common trigger in Singapore. According to him, other common food triggers include fish, nuts and, get this – bird’s nest.  


Experts have long pegged food allergies to children but it seems that adults are developing them, too.

More interestingly, these food allergies aren’t just a continuation of childhood food allergies, according to Ruchi Gupta, a professor of paediatrics at Northwestern University’s Feinberg School of Medicine, whose study on more than 40,000 adults, was published in JAMA Network Open in 2019.

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"We found that about half, 48 per cent, said they developed at least one new food allergy as an adult that they didn't have as a child.

Additionally, about one in four adults said they developed an allergy as an adult and never had a food allergy as a child,” said Prof Gupta. "More research is needed to understand why this is occurring and how we might prevent it."  

Dr Look, too, couldn’t say why food allergies in specific adults occur. “The reason is unclear but it may be related to a delayed sensitisation or cross-reaction process.”

(Photo: Freepik)

However, he commented that adult food allergies could be a sign that your gut microbiota has changed as you age.

“The composition, diversity and stability of our microbiota help to determine how healthy our gut is.” But as we age, the diversity of our gut microbiota reduces and “there is an overgrowth of harmful bacterial opportunists”.

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Furthermore, “changes in diet patterns, decrease in activity levels and an increased intake of drugs and antibiotics, can all affect motility and digestive functions,” said Dr Look.


It goes without saying that you should avoid the food that triggers your allergy, especially once it is diagnosed by your doctor.

And not just the key ingredients. “Check food labels, including additives and flavouring,” said Dr Look.

Mild allergy symptoms can be treated with an antihistamine but it is a good idea to learn how to use an epinephrine auto-injector, advised Dr Look, in case of a severe reaction.

“There are also desensitisation programmes to expose patients to small doses of the allergen under medical supervision to reduce the risk of a major reaction,” he said.

Source: CNA/bk