What are the effects of food intolerances on our bodies?

Food intolerances can have various effects on digestion and overall well-being. In this article, we'll explore just some of the impacts they can have on our bodies, but first, let's look at what an intolerance is. 


What is an intolerance? 

An intolerance is different from a food allergy, as it does not involve the immune system but, rather, the digestive system's inability to properly process certain components of a food. The common dietary culprits are eggs, dairy, wheat, nuts, and yeast. Below are some of the physical effects that intolerances can cause. 

The effects of food intolerance 

Gastrointestinal symptoms

Food intolerances often lead to gastrointestinal discomfort and symptoms such as bloating, gas, abdominal pain, cramps, and diarrhoea. These symptoms can range from mild to severe and can occur shortly after consuming the problematic food.

Nausea and vomiting

Some people with food intolerances may experience nausea and vomiting, particularly if they consume a significant amount of a certain food. This can lead to further digestive distress and discomfort.

Changes in bowel habits

Food intolerances can cause changes in bowel habits, including diarrhoea or constipation. These changes are often linked to the body's difficulty in processing specific food components.


In cases of food intolerance, the digestive system may struggle to absorb certain nutrients properly. This can result in deficiencies in essential vitamins, minerals, and other nutrients, leading to a range of health issues over time.


Chronic exposure to foods that an individual is intolerant to can cause low-level inflammation in the gastrointestinal tract. This inflammation can contribute to ongoing digestive discomfort and may have broader health implications. Prolonged low-level inflammation in the intestinal tract is associated with various health concerns. It can increase the risk of developing conditions such as IBD, IBS and leaky gut syndrome where there is increased permeability in the intestines. 

Fatigue and general discomfort

Gastrointestinal symptoms associated with food intolerance can lead to fatigue and overall discomfort. The body may divert energy and resources to deal with the digestive issues, leaving a person feeling tired and unwell.

Skin and allergic reactions

In some cases, food intolerances can manifest as skin conditions, such as hives or eczema. These reactions are often the result of the body's attempt to eliminate the problematic substances.

Mood and cognitive effects

Some individuals with food intolerances report mood swings, irritability, and cognitive symptoms such as brain fog or difficulty concentrating. These effects may be related to the body's inflammatory response or disruptions in nutrient absorption.

Weight changes

Food intolerances can lead to weight fluctuations, with some individuals experiencing weight loss due to malabsorption, while others may gain weight due to increased consumption of alternative foods that are tolerated but higher in calories.

It's important to note that the specific symptoms and severity of food intolerance can vary widely among individuals and depend on the particular food or food component that is not well-tolerated.

If you suspect that you have a food intolerance, it's advisable to consult with a healthcare professional or a registered nutritionist for proper evaluation and guidance. They can help identify the problematic foods and create a tailored dietary plan to manage your symptoms and ensure you receive adequate nutrition. A pinprick blood or hair sample test can verify the food intolerances. 

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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Chelmsford CM3 & Romford RM1
Written by Lisa Mehlman, DipNT, CNM, mNNA | Nutritional and Holistic Therapist
Chelmsford CM3 & Romford RM1

Lisa Mehlman Dip NT CNM mNNA has been a practising nutritional therapist since 2012. She has a particular interest in weight management, hormonal and digestive health. She now offers Food Detective a quick pin prick blood test to ascertain food intolerances at her clinic in Little Baddow, Essex. The results are ready within a hour.

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