When is an Allergy Really an Allergy?

So, you’ve got a killer headache, a bloated stomach, and you’re having trouble going to the toilet because of what you’ve eaten. Could an allergy be the culprit?

Adverse reactions to food, known as food sensitivity or food intolerance, are on the rise. As many as one-fifth of the population experience negative reactions to food, and many scientists are wondering if environmental factors have a part to play when it comes to food and allergy issues.

Here we cover some of the science behind the growing issue.

Allergy, Sensitivity or an Intolerance?

Firstly, let’s tackle the terminology – food sensitivities with allergic pathophysiology involve immunoglobulin E (IgE) mechanisms, non-IgE-mediated mechanisms or a combination of both. A strong response to the allergen could lead to anaphylaxis, which is defined as a severe allergic reaction of rapid onset affecting multiple tissues that can cause death

On the other hand, food intolerances involve non-immune mechanisms, such as lactose intolerance, in which there is an inability to break down the disaccharide lactose due to a primary or secondary deficiency of the lactase enzyme. Therefore, undigested lactose reaches the colon, where it’s fermented by the gut microbiota, leading to gas production and bloating.

Causes of food intolerance can include:

  • Lack of an enzyme needed to fully digest a food. Lactose intolerance is a common example.
  • Irritable bowel syndrome. This chronic condition can cause cramping, constipation and diarrhoea.
  • Sensitivity to food additives. For example sulphites used to preserve dried fruit, canned goods and wine can trigger asthma attacks in sensitive people.
  • Coeliac disease. Coeliac disease has some features of a true food allergy because it involves the immune system. Symptoms often include gastrointestinal issues as well as those unrelated to the digestive system, such as joint pain and headaches. However, people with coeliac disease are not at risk of anaphylaxis. This chronic digestive condition is triggered by eating gluten, a protein found in wheat and other grains.

But could there be more to this than we initially thought? 

Allergy GraphicHistamine Intolerance

Histamine intolerance affects around 1% of the population and is a result of the body’s impaired ability to metabolize histamine. 

Usually ingested via food, histamine is stored in nearly all tissues of the body. When released, it helps to keep our organs functioning, such as helping the smooth muscle tissue of the lungs, uterus, and stomach contract, dilating our blood vessels and accelerating our heart rates.

People with histamine intolerance are low in the essential enzymes that help break down histamine in the body. Therefore, it starts to build up faster than it can be broken down and causes unwanted symptoms that resemble that of seasonal allergies.

If you eat histamine-rich food or drinks, you may experience hives, itchy or flushed skin, red eyes, facial swelling, runny nose and congestion, headaches, gastrointestinal issues, or asthma attacks. Other symptoms can be more severe, like a drop in blood pressure, heart palpitations and anxiety or panic attacks.

The treatment? Some medications can help. Often, over the cover antihistamines are enough to decrease the histamine load in the body and relieve symptoms. An elimination diet with a trusted healthcare professional will also do the trick and help you see whether histamines are the culprit.

Fructose, Fructan and FODMAP Intolerance 

Common dietary intolerances include fructose, fructans and FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) – a range of carbohydrates that often cause unexplained bloating, gas, abdominal pain or diarrhoea. Here, we explore the traits of each one.

Fructose is a molecule naturally present in foods, including certain fruits, vegetables, and honey but it is also produced from corn as high fructose corn syrup. Humans have a limited absorptive capacity for fructose. Published guidelines for fructose intolerance include eating foods with less than 3 g of fructose per serving. 

Fructans are oligo- or polysaccharides where the most common forms are inulin, levanare and geraminan. The human body has limited ability to break down these oligo- or polysaccharides in the small bowel, and only absorbs 5 – 15% of fructan. Currently, there is no standardized test for a diagnosis of fructan intolerance and no clear guidelines on dietary management in fructan intolerance since there’s no robust published data. Restricting fructan in dietary intake may reduce symptoms in a variety of GI disorders with 24% of IBS patients reporting sensitivity to fructans. 

FODMAPs are a group of short-chain carbohydrates which are poorly absorbed in the GI tract. The monosaccharide, fructose and oligosaccharide fructan are all part of FODMAPs. Disaccharide lactose is found in a variety of dairy products, and polyols are sugar alcohols found in certain fruits, including peaches and plums. Sugar alcohols such as sorbitol, lactitol and xylitol are also commonly found in sugar-free products. At least 70% of polyols are not absorbed in healthy individuals and are rapidly fermented by bacteria. 

The low-FODMAP diet is very well known and suggested for improving symptoms in patients with unexplained gastrointestinal symptoms. To benefit from the diet, strictly adhering for at least 6–8 weeks before reintroducing different groups of FODMAPs is recommended. That way, you can easily determine which group(s) of FODMAPs you are sensitive to.

So, the take-home?

Food issues are on the rise, but that could be down to a host of different causes and reasons. So, working with the correct healthcare professional who can take a good look at your diet and lifestyle before making drastic changes to your life is the best way forward. After all, it may not be an allergy but a gut issue, or vice versa.
What’s for certain is what appear to be allergy symptoms are not always caused by a true allergy.