9.FEB.2021 5 MIN READ | 5 MIN READ

Did you know that our gut can influence whether we develop food allergies or intolerances during adulthood?

We hear a lot about children having food allergies, but did you know that it’s possible to develop food allergies at any point in your lifetime? While it’s not clear why, some adults may develop an allergy to food that they previously had no problems with.

While children may outgrow their food allergies, that’s very unlikely to happen in adults. And chances are, adults won’t be able to count on the passage of time to shake off common food allergy triggers such as peanuts, fish, shellfish (prawns and crabs), and tree nuts like almonds, walnuts and cashews.

The symptoms of an allergy in adults are similar to that in children, and reactions can happen as quickly as within minutes, or be delayed till hours after you eat something your body is adverse to. These food allergy symptoms can range from mild to severe and may include:

  • Tingling of the mouth
  • Swelling of the lips, face, tongue or throat
  • Hives
  • Diarrhoea
  • Vomiting
  • Trouble breathing

Allergy vs intolerance

Allergy vs intolerance
Most physical reactions to food are actually food intolerances but because food intolerance and food allergies have similar signs and symptoms, these two are often confused.

Food allergies cause an immune system response that involves multiple organs in the body and can become life-threatening. Food intolerance is usually less serious and is mostly limited to digestive issues such as stomach aches, cramps, and diarrhoea.

For those with food allergies, they are at risk of a possibly life-threatening allergic reaction called anaphylaxis. This is when your immune system overreacts, and you have a full-body allergic reaction with symptoms such as:

  • Swelling of the throat
  • Weakness or dizziness
  • Rapid or abnormal heart rate
  • Facial swelling
  • Hives
  • Low blood pressure
  • Wheezing

An anaphylactic shock is when someone stops breathing or experience airway blockage due to the airways being inflamed. This could also lead to a heart attack. Those who have experienced, or are at risk of anaphylaxis, should carry an emergency epinephrine (EpiPen) shot just in case.

Gut health and adult-onset food allergies

Gut microbiota or flora, refers to the trillions of bacteria, viruses, fungi, and other tiny living organisms that call our intestines home. With age, our gut flora works with our bodies to keep us healthy, such as helping to control your immune system by communicating with cells of our immune systems called lymphocytes.

A key feature of the gut microbiota in healthy people is its high diversity. Studies have shown that healthy people tend to have greater diversity of gut bacteria compared to those who are frail, or suffering from conditions like obesity, diabetes, atherosclerosis (clogged arteries), and eczema. Adults with allergies have also been shown to have a lower degree of gut bacterial diversity.

The increased use of antibiotics – prescribed for the treatment of infections, and also present in the meat we eat – reduces our gut bacterial diversity and may be a reason why some people may not have the immune defences to prevent allergies. This is because antibiotics are well-known for disrupting the healthy bacteria and fungi that live in the gut.

Modern sanitation reduces the array of different bacteria we’re exposed to and this makes our gut flora less diverse. This may lead to our immune system reacting to things that should be harmless and causing an allergic reaction.

As we age, the immune system undergoes changes and declines, which impacts our health. This weakening of the immune system increases our risk of bacterial and viral infection and could also upset the balance of our gut flora. Reduced bacterial diversity in the gut has also been related to inflammatory bowel disease, a disease caused by an abnormal gut immune system.

Importance of a healthy digestive system

Healthy digestive system
Our digestive system ages along with us and common issues that can crop up include constipation and slowing down of the digestion process. Constipation can be caused by medication, inactivity, and reduced intake of water.

As there might be a relationship between your gut health and allergies to food during adulthood, it is important to maintain a healthy digestive system. This includes a balanced gut flora and ensuring that you have more good bacteria than bad bacteria in your gut. Things that could throw off your gut flora include having a diet high in sugar and fat and low in fibre.

This is why eating a balanced diet with plenty of fruits and vegetables, whole grains, legumes, and beans, may help to maintain a balanced gut flora. A diet high in fibre also helps prevent constipation. Fermented food such as yoghurt and kimchi contain healthy bacteria called Lactobacilli which could help reduce harmful bacteria in the gut.

Cutting down on your sugar intake lowers your blood sugar levels, which is beneficial because high levels of blood sugar may encourage the growth of bad bacteria.

Do note that we’re not against taking the antibiotics prescribed by your doctor as they are a great way to fight bacterial infections. But as they are known to disrupt the gut flora, it’s imperative that you finish any course of prescribed antibiotics as advised by your doctor, and at the same time, keep eating healthily in order to rebalance your gut flora.

If you’ve had a reaction to food that you normally eat, there’s a possibility that it’s gut related. Don’t suffer in silence and do see a gastroenterologist who can help you with your tummy troubles, suggest ways to help better your digestive system, and prevent more food intolerances or allergies.


Article reviewed by Dr Wang Yu Tien, gastroenterologist at Gleneagles Hospital


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Wang Yu Tien
Mount Elizabeth Hospital