Obesity and Allergies: How are they related and what can we do?

In Singapore, obesity is defined as a body mass index (BMI) of more than 27.5. Obesity has a deleterious impact on a person’s health — with an increased risk of coronary heart disease, stroke, high blood pressure, diabetes, osteoarthritis, depression, poor sexual function, cancer, and more. 

The diet we consume is known to play a major role in the development of obesity. One that consists of mainly processed food and fast food which are high in calories and have minimal proper nutrients. Consuming this diet in the long run can lead to chronic surplus of calories intake, leading to weight gain. Currently, 38% of the people in the world is obese, and this trend is rising continuously.

In this article, we explore the association of obesity and common allergy medical conditions. This article is written in hope of highlighting the importance of managing weight to reduce risk of immunological conditions, hence improving one’s quality of life.

Physiological Inflammation from Obesity

In obesity, there is excessive build-up of fat tissues in the body — a condition known as adipogenesis. The fat cells known as adipocytes increase in size and numbers. The adipocytes produce chemicals and hormones known as adipokines that regulate the body’s overall wellbeing. In obesity, as there are more and bigger adipocytes, more adipokines are produced, leading to disruption of the body's internal equilibrium. 

Over time, with excessive adipogenesis, excessive adipocytes and adipokines production, the body is in constant oxidative stress and inflammation. It is postulated that this low grade inflammatory state of an obese person increases the susceptibility towards allergic conditions.

Obesity and Food Allergy

During the chronic inflammatory state of obesity, the gastrointestinal linings also undergo changes. The intestinal microbiome becomes less diverse, leading to a weaker intestinal barrier and increased permeability of food/ protein/ particles/ allergens through the intestine layer. The external proteins or allergens can pass through the intestinal linings into the blood circulation, leading to abnormal activation of the immune system and food allergies.

What can we do?

As obesity contributes to the development of food allergies;

• losing the extra weight with diet and medical management of weight loss can alleviate food allergies symptoms. 
• Identifying the allergenic food and avoiding the food particles are keys in preventing an allergic reaction. 
• In mild cases, symptomatic medications such as antihistamines or steroids can be used. 
• In life-threatening anaphylaxis reactions, immediate medical attention with adrenaline is required to reverse the dangerous allergic condition.

Obesity and Allergic Rhinitis

Obesity is clinically shown to increase the risk of allergic rhinitis. However, this association is more seen in the paediatric group rather than in obese adults. Hormone and chemicals such as leptin and interleukin-1beta protein can be found in high levels in obese individuals. These proteins can activate the immune inflammatory response, increase susceptibility towards allergens and increase risk of allergic rhinitis.

It is also hypothesised that due to the pro-inflammatory state of obesity, the mucus membrane lining of the nose passage can be constantly swollen and inflamed, leading to increased permeability of the external allergenic particles which result in activation of the immune system and allergic symptoms in the form of rhinitis.

Interestingly, a person with allergic rhinitis has an increased risk of becoming obese due to hampering of physical activities following rhinitis symptoms or becoming sedentary due to side effects of medications (such as drowsy antihistamines) of rhinitis.

What can we do?

Due to the association discussed above between obesity and allergic rhinitis;

• Weight management can improve the overall outcome of allergic rhinitis. 
• Symptomatic medications such as antihistamines, nose sprays, saline rinse are commonly used to manage rhinitis symptoms. 
• Identifying culprit allergens (tends to be airborne allergens) can be useful, and avoidance of allergens aid to prevent allergic rhinitis. 
• If avoidance is inevitable, immunotherapy can be a medical option to manage allergic rhinitis.  

Obesity and Asthma

The relationship between obesity and asthma is stronger among the paediatric group with greater risk of developing asthma, more exacerbation of asthma, and harder to manage the condition.

The negative impact of obesity on causing respiratory inflammatory conditions such as asthma is through complex mechanisms. Firstly, there is an innate genetic susceptibility of having asthma. This is further coupled with low grade chronic inflammatory state in obesity, leading to structural changes of the respiratory tract. To make things worse, obesity is also implicated in hormonal changes and less microbiome diversity, leading to predisposition to environmental triggers (pollution/ allergens) of developing asthma.

High sugar and fatty diet in obesity can also reduce the lung function. As excessive fat tissues accumulate around the chest and abdomen, the movement of the lungs and chest wall muscles can be restricted, leading to increased work of breathing. 

In a vicious cycle, the repeated use of corticosteroid in asthma or poorly controlled asthma can also cause weight gain. Restricted physical activities may be seen in asthma patients. Weight gain can occur over time with a sedentary lifestyle.

What can we do?

As obesity contributes to the asthma and related long-term comorbidities;

• Management of weight can improve asthma-related long-term comorbidities and improve quality of life, reduce exacerbation episodes and hospitalisation.
• Optimisation of inhalers — both rescue and maintenance inhalers remain the backbone of treatment of asthma though it can be less effective in those with weight issues.

Obesity and atopic dermatitis (eczema)

Obesity can affect the skin in a few possible ways. We know obesity promotes inflammatory processes in the body and can affect the hormones and chemical substances of the body.

People with obesity may have an impaired skin epidermis barrier due to increased sweating and increased blood pressure. The skin microbiome can be less diverse in a person with obesity, with more colonisation of Corynebacterium spp. There is less lipid content on the skin surface in an obese person, leading to faster skin dehydration, and increased risk of developing atopic dermatitis. Interestingly, one can have increased risk of developing atopic dermatitis if the mother is obese before pregnancy.

What can we do?

Weight loss has a beneficial effect in overall treatment of atopic dermatitis, hence promoting a healthy lifestyle and weight loss can complement the treatment of atopic dermatitis. Additionally:

• Optimisation of steroid, moisturiser and emollients, antihistamines are the mainstay treatment of atopic dermatitis. 
• In more severe recalcitrant cases, second line treatment with phototherapy and immunosuppressant may be required to control the disease.

What Have I Learnt Today?

• Being overweight and obese increases risk of developing adverse health conditions.
  
• Less discussed, obesity has a negative impact on allergy and immunological conditions such as food allergies, eczema, allergic rhinitis and asthma.
  
• In an obese person, the body is constantly undergoing low-level of chronic inflammation. The excessive fats in the body produce hormones and chemical proteins that can cause oxidative stress and dysregulation of the body’s internal equilibrium, resulting in development of allergies and immunological medical conditions.
  
• Managing and reducing excessive weight, achieving a healthy targeted weight can complement the treatment of immunological conditions by reducing overall inflammation in the body and hence improving a person’s overall quality of life.
  
• If you have difficulty losing weight despite healthy eating habits and exercises, you can reach out to your trusted physicians for medical management of obesity.

References:

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