We’ve said it before, we all have reactions to food and food disturbances. Adverse food reactions had become one of the most common doctor’s office visits. In a study performed in the United Kingdom, 20% of the population reported having a food intolerance, and in Germany, one-third of the population studied reported having reactions to food. When placebo-controlled challenges were done, it turned out that less than 2% of the UK studied population resulted in food intolerance. Similarly, only 3.6% in the German study presented an adverse reaction to food. Current information shows that women are more common to self-perceived food adverse reactions when compared to men. Could it be possible that we don’t know what our bodies are reacting to? Let’s dive in and find out about adverse food reactions, their symptoms, and differences.

The classification of adverse food reactions:

Non-immune adverse reactions:

These reactions include the toxic effect of food when it becomes spoiled and the patient’s metabolic reaction to food or medicine that their body cannot process.

Metabolic reactions:

The inability to metabolize or fully digest a certain food and therefore react adversely is what we know as food intolerance. Generally, food intolerances are related to a digestive enzyme deficiency followed by an inability to digest certain food, and commonly to the amount of food. Nevertheless, food intolerance is often confused by the patient with a food aversion, related to psychological distress caused when eating that food and provoking symptoms like nausea and vomiting.

• Food intolerance is a non-threatening, not an immune-mediated reaction.
• The most common gastrointestinal symptoms are:
  • Gastrointestinal discomfort, bloating.
  • Flatulence.
  • Diarrhea
  • Abdominal pain.
  • Cramping
• Other symptoms may include:
  • Headaches and migraines.
  • Musculoskeletal problems.
  • Behavioral changes.

Lactose intolerance:

Lactose is a sugar contained in food and its products; it is composed of galactose and glucose. Therefore it is a disaccharide. Later, when lactose enters our gut, the enzyme lactase separates lactose into galactose and glucose before its absorption. When lactase becomes unavailable, the indigestible lactose moves through the gut entering the bowel where bacterial fermentation begins. This, leading to gas production, and liquid gets drawn to the gut resulting in osmotic diarrhea.

The prevalence of lactose intolerance is varied among studies, reporting evidence from 7% to 20% in adults. It is believed that neonates have a functional amount of lactose, but this enzyme tends to decline after weaning.

Furthermore, the diagnose of lactose intolerance could be by made a food challenge test. In this test, the patient consumes 50g of a lactose load. Afterward, the symptoms related to the bloating and presence of osmotic diarrhea or flatulence confirm the diagnose. Likewise, the intensity of the symptoms is related to the type of product and the patient’s amount consumed. Needless to say, lactose intolerance is considered a variant of human metabolism rather than a disease.

Alcohol dehydrogenase deficiency:

In brief, alcohol dehydrogenase deficiency conduct to the inability to metabolize alcohol. Commonly found in patients of Asian descent. Flushing and vomiting are the most common symptoms of this kind of deficiency.

G6PD:

Glucose-6-phosphate dehydrogenase is a primary metabolic enzyme; its deficiency is caused by and a genetic disorder. This deficiency leads to oxidative injury to red blood cells due to the acute hemolysis caused by the ingestion of drugs or food.

Fructose intolerance:

In contrast with lactose, fructose is absorbed by diffusion in our gut with the help of a GLUT5 transporter and a glucose-dependent co-transporter, GLUT2. Hence, the fructose passive diffusion depends on a great matter of the concentration glucose. Accordingly, with lactose intolerance, the fructose’s remaining molecules enter the bowel, where colonic fermentation causes gas and inflammation.

Regularly, the gastrointestinal symptoms of enzyme deficiencies are related to the ones presented by patients with irritable bowel syndrome. Intolerances like lactose, alcohol, and fructose can be presented when the patient experiences changes in their microbiome or a viral infection. Therefore, medical diagnose could be easily misinterpreted.

Furthermore, in a descriptive study made in children, it was concluded that girls are more self-aware of symptoms related to food adverse reactions, and they tended to avoid more foods than their male counterparts. Interestingly, when symptom inducing foods were included in their diet, the symptoms were rarely related to severe symptoms caused by such foods’ ingestion. Lastly, the study supports the idea that children with IBS symptoms and self-perceived GI pain are more likely to have a decreased quality of life and psychological distress.

In conclusion, as a patient is essential to be aware of your symptoms and body. It is fundamental to know the differences of adverse reactions to food; the last information lets us have a higher quality of life and a better understanding of what is happening. Also, as a patient, it will improve the quality of diagnosing and prescription treatment. Lastly, you must know that each of these intolerances must be treated with a proper dietetic approach. The elimination of a specific group of food is likely to cause a nutritional deficiency.

Chumpitazi, Bruno P., et al. “Self-perceived food intolerances are common and associated with clinical severity in childhood irritable bowel syndrome.” Journal of the Academy of Nutrition and Dietetics 116.9 (2016): 1458-1464.

Yu, Linda Chia-Hui. “Intestinal epithelial barrier dysfunction in food hypersensitivity.” Journal of allergy 2012 (2012).

Turnbull, J. L., H. N. Adams, and D. A. Gorard. “The diagnosis and management of food allergy and food intolerances.” Alimentary pharmacology & therapeutics 41.1 (2015): 3-25.

Cox, Amanda L., and Scott H. Sicherer. “Classification of adverse food reactions.” Journal of Food Allergy 2.1 (2020): 3-6.