There are many different ways that a person can react to a food. Although we may say we have an ‘allergy’ to a food, we might in fact be experiencing an intolerance or a sensitivity. This is why trying to figure out whether you have a problem with a food can be a bit of a minefield.
Symptoms which are often associated with food reactions include depression, headaches/migraines, skin complaints, indigestion, nausea, hives, irritable bowel (bloating, diarrhoea, cramps), fatigue, weakened immune system, joint pain, weight loss or gain.
So, in what ways can the body react to foods?
Immune antibody response
Antibodies are used by the immune system to identify and neutralise foreign objects such as bacteria and viruses. In certain individuals they can also react to foods. The body has different antibodies and it can be any one of these which could cause a reaction. An IgE antibody response will usually involve an immediate reaction such as wheezing or swelling. These types of reactions can be life threatening and are the type of allergic response which GPs will test for. Common IgE reactions are to peanuts and shellfish but can be to any food. However, other antibody reactions occur which can often go undetected. These include IgG and IgA reactions. These reactions can sometimes be delayed in their response – you might not feel unwell until a few hours or even days later.
Digestive enzyme or absorption deficiency
If we are lacking specific enzymes to digest foods then this can also cause a reaction. This would be classed as an intolerance rather than an allergy. So someone lacking the lactase enzyme would have trouble digesting the milk’s lactose component. Classic signs of lactose intolerance include diarrhoea, cramps and bloating.
Specific populations show particularly high levels of intolerance to lactose - approximately 95% of Asians, 60-80% of Africans and 50-80% of Hispanics. The prevalence of lactose intolerance amongst people of northern European origin is about 2%.
Other absorption deficiencies which can lead to ‘foods not agreeing with you’ include fructose malabsorption (due to deficient fructose carriers in the cells of the intestines), fat malabsorption caused by gall bladder/ bile issues and an inability to digest food properly caused by low stomach acid production. Signs of low stomach acid include bloating, belching, feeling full after meals, acid reflux (paradoxically), indigestion and nausea.
A common auto-immune response is Coeliac’s disease. This condition means individuals can’t tolerate gluten in food. However, it is possible to be non-coeliac gluten intolerant and this can often go undiagnosed.
Biogenic amines – e.g. tyramine and histamine
Amines are chemicals found in certain foods such as aged cheese, red wine and fermented foods. Some individuals find it difficult to metabolise amines due to natural genetic variation. There is a link between amines and migraines.
Foods naturally containing reactive substances
For example the chemicals salicylate (found in many fruits, vegetables and additives) and solanaceae (found in foods which are members of the nightshade family such as aubergines, bell peppers, tomatoes and potatoes) may lead to health issues in some individuals. Salicylates have been linked to mood and behavioral issues. Solanaceae has been associated with inflammatory conditions such as arthritis.
So as you can see, there are many ways that foods can affect us – mechanisms are varied. Remember, if excluding foods or food groups it is even more important that you take care to eat a well-balanced diet. It is always best to discuss an exclusion diet with a healthcare professional to be sure you are getting it right.
Many clients come in to see me suspecting they have food allergy issues when in fact, the problems are more about gut health. Gut flora imbalance, low digestive enzymes, or gut irritation can often make people more sensitive to certain foods. Removing the food might be beneficial for a shot period of time but working with a nutritional therapist to heal the gut will usually lead to improved symptoms and often also the ability to reintroduce foods back into the diet.