If you're tired all the time or have chronic fatigue, ruling out food sensitivities, intolerances and allergies as potential underlying causes is a good idea and can be relatively straightforward.
Often these 3 terms are used interchangeably, but if you’ve noticed certain foods are making you tired or giving you other symptoms, how do you know whether it’s an allergy, sensitivity or intolerance?
Here’s a simple overview:
Food allergies involve the overreaction of the immune system to a food and symptoms occur instantly or very soon after eating. These can include rashes, swelling or difficulty breathing. Immunoglobulin E (IgE) are antibodies produced by the immune system in response to an allergic reaction. In some cases food allergies can be life threatening, so it’s important to see your GP for a referral for testing if you suspect you are allergic to any foods or are having these types of reactions after eating.
Food intolerances may arise when we don’t have enough of the enzymes required to fully digest a food. There’s usually a delayed response, hours or even days later. Lactose intolerance is probably the most well-known, and occurs when someone cannot produce enough lactase (enzyme) to break down the lactose (sugar) in milk. This can be due to genetics, increased age or other digestive issues such as coeliac disease and inflammatory bowel disease. It’s thought that 65% of the world’s population may be lactose intolerant(1).
Symptoms include bloating, flatulence, nausea, stomach cramps and pains and diarrhoea.
Histamine intolerance is another example, some people may have genetic issues which means they cannot produce enough of the enzyme DAO which is needed to clear histamine from the body and it builds up, causing symptoms. Deficiency of certain nutrients can also affect the production of this enzyme.
Food sensitivities are thought to involve a different part of the immune system and are also associated with a delayed response. Immunoglobulin G (IgG) are the antibodies produced in response to a food sensitivity. Digestive symptoms are common, but food sensitivities may also cause:
Fatigue
Headaches
Brain fog
Irritability
Muscle aches and pains.
Personally, I used to suffer from crippling headaches and sore neck and shoulders muscles and had tried everything - I was even told to take 6 painkillers 4 times a day for 7 days! It wasn’t until a massage therapist suggested gluten could be the cause, and I removed it from my diet for a few days, that I noticed a huge improvement. Whenever I ate gluten-containing foods, the headaches and muscle pains returned. Looking back I can remember going out for pizza at lunchtime, going home and having to have a nap! This is known as non-coeliac gluten sensitivity and there is increasing research into this area(2).
If you feel certain foods are causing you symptoms, digestive or otherwise, it’s also worth remembering that in many cases, it’s not the food that’s the issue, but the environment - the gut. Dysbiosis, or gut bacteria imbalance, and inflammation in the gut can make us more sensitive to foods, and intestinal permeability (leaky gut) may allow food particles to cross the gut barrier and enter circulation, causing the immune system to react (as they shouldn’t be there), resulting in symptoms.
It's not clear why reactions to food may cause fatigue, but we do know that the immune system requires a huge amount of energy, and if food is added to the list of things it needs to respond to, then energy may be diverted to the immune system from elsewhere, leaving us depleted.
The 3 most common issues I see in my clinic are gluten and dairy and histamine intolerance, which can often affect many body systems simultaneously. Whilst testing is available for food sensitivities and intolerances, if you have digestive issues and are reacting to lots of foods, the first steps are usually to eliminate foods, often in a certain order, and work on healing the gut (a stool test may be useful here) to alleviate symptoms before a phased reintroduction of foods.
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The content on this webpage is not intended to constitute or be a substitute for professional medical advice, diagnosis, or treatment.