What is the link between obesity and allergic diseases?
Overweight and obesity, like allergic diseases, are among the major public health problems in developed countries. Both have already been labelled as epidemics. This is not surprising, as the prevalence of obesity worldwide has tripled since 1975 [1]. There has also been a two- to three-fold increase in the prevalence of atopic diseases – allergic rhinitis and bronchial asthma [2]. This is largely due to urbanisation, as well as climate change and lifestyle changes.
According to the WHO, in 2016, 39% of the world’s population was overweight. Obesity affected over 13% of adults (18% and 7% of children, respectively) [3]. What is the situation in our country? Every second person over the age of 15 has weight problems [3]. In 2014, in an OECD study, 53.3% of people in Poland declared that they were struggling with overweight or obesity.
Obesity among children and adolescents
Overweight and obesity have recently become a huge problem among children and adolescents. In the European ranking, polish adolescents are fifth in terms of the prevalence of overweight. They are in the lead when it comes to the upward trend in this ranking. This means that children in Poland are gaining weight faster than in other European countries [4].
What does this mean? As is well known, there is a long list of health consequences associated with excessive body weight. Obesity has been proven to be a factor that strongly influences the risk of developing and the course of many diseases. These include, above all, hypertension, type 2 diabetes and cancer. It also intensifies inflammatory reactions. Persistent inflammation is a basis for the development of autoimmune diseases and allergies [5]. What is more, recent studies have shown that obesity can lead to immune disorders [6].
It all starts with diet
One of the main causes of overweight and obesity is an unhealthy diet – irregular, high in simple carbohydrates and fat, and high in calories [1]. However, many scientific studies indicate that diet may also be linked to the occurrence of allergic diseases [7]. Today – unlike several decades ago – it is believed that introducing potentially allergenic foods into an infant’s diet at an early stage helps to prevent food allergies [7].
However, the role of diet in the development of allergic diseases is significant not only in early childhood, but also in the prenatal phase. The maturation of all foetal organs and systems depends on how a pregnant woman eats. Providing the right amount of calories, as well as vitamins and microelements, is crucial, among other things, in the context of the development of the immune system [7].
In addition, supplementation is very important. Studies have shown that vitamin D3 supplementation in pregnant women reduces the risk of bronchial asthma and infectious diseases in newborns [7]. This risk is increased by high birth weight and overweight in early childhood [7], which has been observed particularly in female children.
Furthermore, a correlation has been demonstrated between the severity of atopic disease symptoms and fruit and vegetable consumption in young children. The higher the proportion of such products in the diet, the lower the severity of allergic rhinitis, asthma and other allergic diseases [7].
Obesity, asthma and gut microbiota
The relationship between obesity and asthma is often emphasised, with gut microbiota disorders being one of the common denominators in their development [7]. A characteristic phenotype of obesity-related asthma has even been identified. As indicated by numerous scientific studies, in this phenotype, weight loss improves disease control, while weight gain worsens the patient’s condition [7]. There are two forms of obesity-related asthma. The first occurs in young people and is associated with allergies. The second mainly affects slightly older patients (e.g. middle-aged), especially women who do not have allergies [7].
However, there is no consensus as to which of the two diseases – asthma or obesity – should be considered primary to the other. It is possible that people with asthma – due to their accompanying shortness of breath – avoid physical activity, which is a factor contributing to obesity [7].
However, the link between severe bronchial asthma and obesity is indisputable. In practice, obese patients are often forced to take higher doses of medication [10]. This is due to chronic inflammation resulting from the immune activity of adipose tissue [7].
Immunologically active fatty tissue
Many scientific publications state that fatty tissue is immunologically active. What does this mean? In light of the knowledge we have gained since the 1980s, it can no longer be said that fat is merely an energy source for the body [8]. Adipose tissue cells produce hormones such as leptin and adiponectin [7,8]. Leptin (the satiety hormone) is produced exclusively by adipocytes, i.e. the main fat cells [8]. Therefore, adipose tissue is considered an endocrine organ [8].
Leptin and adiponectin influence metabolic processes on the one hand, and on the other hand, they can have a pro-inflammatory effect. However, they are not the only mediators of inflammatory processes originating in adipose tissue. There are many other inflammatory cytokines associated with adipocyte activity. These include IL-6, IL-1β, TNF-α, MCP-1, etc. [8]. It is worth noting here that visceral adipose tissue (covering internal organs such as the heart, kidneys and liver) exhibits greater pro-inflammatory activity than subcutaneous adipose tissue [8].
Alarm: inflammation
A continuous inflammatory process leads to the disintegration of the epithelium. As a result, harmful factors penetrate uncontrollably and affect the deeper layers of the respiratory tract mucosa or dermis [9]. Inflammation then begins to develop in these deeper parts of the epithelium. This is how bronchial asthma, allergic rhinitis, chronic sinusitis and atopic dermatitis may begin [9].
Aleksandra Lipiec
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translation: Julia Majsiak
Publication: 4.03.2024
Updated: 22.05.2025
