Food intolerances: symptoms and triggers

Does your stomach start rumbling after you’ve had a glass of milk at breakfast? Or do you find your skin itches after you’ve eaten a hazelnut croissant? This could be due to a food sensitivity, meaning that your body reacts with complaints after you’ve eaten certain types of food.

Experts distinguish between two classes of reaction to foodstuffs, namely intolerances and allergies. In the case of an intolerance, your body only partially digests a substance – lactose intolerance is one example. If you have an allergy, your immune system treats components of particular foods – such as peanuts – as intruders.

However, not everything that upsets your stomach after eating is a sensitivity. Food poisoning triggers similar complaints, but it has a completely different cause. And coeliac disease is neither an intolerance nor an allergy in the traditional sense; it’s actually an autoimmune disorder. You can find out more about these other issues in the two boxes below.

The complaints may be similar, but the processes in the body are anything but. In fact, there’s a different mechanism behind every form of food sensitivity.

Intolerances: reactions without an immune response

If you have an intolerance, this means your intestines cannot cope with a particular food component. The immune system is not involved in this. The best-known example is lactose intolerance, where the body produces too little lactase, or none at all. Lactase is an enzyme which usually breaks down milk sugar (lactose) so that the intestines can absorb it. If there isn’t enough lactase to do this, the lactose passes into the large intestine either wholly or partially undigested. Bacteria then metabolise the lactose there, producing gases and acids. These can trigger complaints such as flatulence, abdominal pain or diarrhoea. 

However, an intolerance isn’t always a case of a lack of enzymes. With fructose malabsorption, the problem is transport; specifically, the small intestine has insufficient proteins to transport the fructose to cells where it can be absorbed. The good news is that while intolerances can be unpleasant, they’re not life-threatening. And if you do have an intolerance, you’re not alone – around 20% of people in Switzerland suffer from some form of intolerance.

Food allergies: when the immune system reacts

If you have an allergy, this means your immune system is sounding the alarm when it shouldn’t be. It’s considering an essentially harmless protein in food to be dangerous and responding by producing antibodies, known as immunoglobulin E (IgE). If you come into contact with the protein again, your body will activate its defences. Experts distinguish between two types of allergy. There are primary allergies, which occur during childhood, and secondary allergies, which develop later and are often related to an existing pollen allergy. In this case, specialists talk about cross-allergies: if a protein in a foodstuff resembles a known pollen allergen, the immune system can confuse the two substances and react to the foodstuff as well. Between 2% and 6% of people in Switzerland are thought to have some form of food allergy.

From milk and fruit to eggs and nuts, there are many triggers for sensitivities. In the case of allergies and intolerances, the body often reacts to similar foods. Many of them contain particular proteins or types of sugar that the body sometimes has difficulty processing. However, what happens in the body in each case can vary. We’ve put together an overview of the most common sensitivities below:

From dairy products to red wine: typical triggers of intolerances

The following food components are particularly likely to cause problems in cases of intolerance:

• Lactose: all milk and dairy products contain lactose. People who are lactose-intolerant produce too little of the enzyme lactase, or none at all. This means that any lactose they consume remains undigested in the intestine. By the way, having a milk sensitivity does not necessarily mean you are lactose intolerant. Some people actually have an allergic reaction to milk protein.
• Fructose: fruit, fruit juices and many sugary foods contain fructose. In the case of fructose malabsorption, the small intestine does not absorb it properly. Experts make a distinction between this and hereditary fructose intolerance, which is genetic.
• Histamine: hard cheese, red wine and sauerkraut contain a lot of histamine. The enzyme diamine oxidase breaks down histamine in our bodies; in cases of histamine intolerance, the body simply doesn’t produce enough of this enzyme – or doesn’t produce any at all. It’s worth noting here that whether histamine intolerance actually exists is a matter of some debate among researchers. 

Spotlight on allergens: nuts and more

According to the aha! Swiss Allergy Centre, these are the most common foodstuffs that can cause an allergic reaction:

• Cow’s milk: this is one of the most common triggers in children. In Switzerland, one in five children with a food allergy reacts to milk – or more precisely, to milk protein. Fortunately, most children lose this food allergy as they age.
• Eggs: these can often trigger an allergy in childhood as well. Those affected react to certain proteins in the egg white. In many children, this allergy disappears after a few years.
• Nuts and peanuts: almonds, walnuts, hazelnuts and peanuts are some of the most persistent allergy triggers. This is because their storage proteins can withstand heat and stomach acid. This type of allergy usually lasts a lifetime.
• Fish and seafood: people who are allergic to these types of food also react to certain proteins. By the way, it’s rare for someone to be allergic to both fish and seafood. 

From a rumbling stomach to itching or even shortness of breath, there’s a whole range of symptoms associated with food sensitivities. Exactly which ones you experience will depend on whether you have an intolerance or an allergy. Intolerance mainly affects digestion: flatulence, abdominal pain, stomach cramps, diarrhoea and constipation are typical symptoms. You may also suffer from rashes, headaches and fatigue. The complaints caused by an intolerance can be unpleasant, but they are not life-threatening.

Allergies, on the other hand, manifest themselves in very different parts of the body. Typical symptoms can appear in the following places:

• The skin: itching, burning, swelling, hives and redness
• The respiratory tract: runny nose, cough and breathing problems, including shortness of breath
• The stomach and intestines: nausea, vomiting, abdominal pain and diarrhoea
• The eyes: itching, redness and swelling
• The cardiovascular system: palpitations and dizziness

The most severe form of an allergic reaction is anaphylactic shock – a medical emergency. This can result in a drop in blood pressure, shortness of breath, organ failure and circulatory arrest within minutes.

Symptoms can occur at different rates depending on the type of sensitivity. Because complaints may not appear until some time after eating, it’s not always immediately clear which food is to blame for an intolerance. In the case of severe allergies, on the other hand, reactions tend to be rapid, with symptoms appearing immediately after eating. Even tiny amounts are enough to trigger a reaction. 

The only way to find out if you have a food sensitivity is by getting tested or having an in-depth discussion with your doctor. Which method is best depends on what you suspect to be the trigger.

A specialist in gastrointestinal disorders can determine whether you have coeliac disease (see box above). Please remember that you should not attempt to diagnose yourself or to start a new diet without professional supervision. Otherwise, you run the risk of developing a deficiency in key nutrients. 

Having an intolerance doesn’t necessarily mean you have to give things up completely: just try to limit your intake of the food that triggers it, or avoid it whenever you can. The body’s tolerance levels vary from person to person. Specialist nutritionists can help you work out your personal limits. For lactose and histamine intolerances, there are also enzyme supplements available in tablet form which you can take to aid digestion.

If you have an allergy, however, the rule is clear: you must avoid the foods in question. Oral immunotherapy is also available for milk, egg and peanut allergies. This involves gradually increasing your intake of a particular allergen so that your body gets better at tolerating it over time. A doctor will monitor you closely throughout this process. 

You won’t notice a food sensitivity itself – but the complaints it causes will certainly make themselves known. These tips will help you on a day-to-day basis:

• Always check the ingredients: remember to take a look at the list of ingredients, even on products you buy on a frequent basis. Manufacturers sometimes change their recipes.
• Try special products: opt for lactose- or gluten-free alternatives if necessary. Labels such as the Swiss Allergy Seal of Quality show you instantly which products are suitable. If you can’t find anything suitable, ask in store.
• Carry emergency medication for your allergy: always carry medically prescribed emergency medication with you – especially when you’re at a restaurant or while travelling. That way, you can act straight away if you’ve accidentally eaten something you shouldn’t have.

If you’d like to find out more about food sensitivities, the aha! Swiss Allergy Centre can provide information and advice.

A food sensitivity can have an impact on your daily routine. But if you’re well informed, you’ll soon discover new favourite dishes. Your doctor and nutritionist can help you along the path. With the right approach eating will soon be a pleasure again – as it should be.