Dairy and Asthma

Dairy is an allergenic food group (others include: egg,peanut and soy) that affects people with asthma, especially children.  Having dairy allergies during infancy/childhood is also a risk factor in developing respiratory allergies such as asthma in later years.

Introduction

What is Asthma?

Asthma is a common long-term condition that results in coughing, chest tightness, wheezing, and breathlessness.

Asthma symptoms do not appear all the time. Some asthma patients may not have symptoms for weeks or months. Nevertheless, asthma has to be treated daily to lower the risk of symptoms and asthma attacks.

Many people with asthma usually start with childhood asthma, but adults can develop asthma too.  There are a lot of things that can make asthma worse and common asthma triggers include: 

• Colds and viruses
• Pets
• Pollen
• Pollution
• House dust mites
• Stress

Asthma  types  vary in severity. Nonetheless, there is always the risk of an asthma attack for every type of asthma. A severe asthma attack could even result in death.

Although there are up to 10 different types of asthma, this article will focus only on allergic asthma.

What is Dairy?

Dairy is food products made from milk, including milk from cows, buffalo, goats and sheep. Common dairy products are made from milk and they include:  butter, cheese, cream, ice cream, fromage frais, and yoghurt.

Correlation between Dairy and Asthma

The Role of IgE

The immunoglobulin E (IgE) molecule is an antibody produced by the immune system. The purpose of IgE is to mediate allergic immune responses (and also to help your body fight against some types of parasitic infections). Exposure to allergens like dust or pollen, can trigger the body to produce and release IgE. These IgE antibodies bind to the allergen and trigger an inflammatory response that corresponds with allergy symptoms such as: 

• Skin rash
• Sneezing
• Swollen lips 

When the inflammatory response causes asthma, it is known as allergic asthma. The common symptoms are:

• Chest tightness
• Wheezing
• Shortness of breath
• Recurrent cough

Allergic Asthma

Allergic (Atopic) asthma can be triggered by allergens such as pollen, pets and dust mites.  In 80% of people with allergic asthma, there is usually the presence of one or more allergic conditions.⁽¹⁾ These are:

• Atopic dermatitis (AD) – skin irritation, such as hives and eczema
• Food allergy (FA) – for example milk products, peanuts and egg white
• Allergic rhinitis (AR) – seasonal allergies like hay fever

The Atopic March

The atopic march or allergic march refers to the natural progression of allergic disease from infancy to adulthood. It usually starts with AD, and progresses to FA, then AR and finally asthma. If you have one allergic condition, it increases the risk of developing the other conditions as well.

AD and FA have the highest incidence in the first 2 years of life, whereas AR, wheezing and asthma often start at school age.⁽¹⁾

Atopic Dermatitis (AD)

AD affects between 11 and 20 percent of UK children. AD is most commonly diagnosed in the first six months of an infant’s life, before FA, AR, and asthma development. AD is the result of epithelial cell defects in a person with a genetic and/or environmental tendency for Type 2 inflammation. ¹ Epithelial cells are found in the outermost layer of the skin and act as a barrier to minimise water loss and protect the body from foreign substances, including toxins, bacteria and allergens like dust mites and pollens.

The filaggrin (FLG) gene gives instructions to make a large protein called profilaggrin in the epithelial cells. The profilaggrin molecule contains filaggrin protein that plays an important role in the skin’s barrier. It acts as the skin’s moisturising factor to maintain the hydration of the skin.

FLG gene mutations are strongly associated with AD. 20 to 30 percent of people with AD have an FLG gene mutation compared with 8 to 10 percent of the general population without AD. ⁽²⁾ These mutations result in the abnormally short profilaggrin molecule that cannot produce filaggrin proteins. As a result, a lack of filaggrin impairs the skin's barrier function, allowing excess water to be lost, causing dry skin.

Food Allergy (FA)

The current prevalence rates of food allergy are believed to be between 4 to 8 percent. The percentage of children with at least one food allergy was 8.2% during the first 5 years of life, with a peak age of diagnosis between 12 and 17 months. 

The incidence of egg, milk, peanut and soy allergies over the first 5 years of life ranged from 1.1% to 3.4% with a peak age at diagnosis between 12 and 17 months for egg and peanut allergies. The peak age of diagnosis for soy or milk allergy is between 6 and 11 months. ⁽³⁾ 

The presence and severity of AD correlate positively with the risk of developing FA. Children with AD are six times more likely to develop an FA compared to healthy peers. ⁽¹⁾

A long term study on the Isle of Wight found a significant association between FLG mutations and FA at 10 years and 18 years. The study associated FLG mutations with all causes of FA rather than one specific food allergen. ⁽⁴⁾ 

FA in early childhood is often due to milk and egg allergies which tend to go away while in older children and adults, peanut and seafood allergies become worse and tend to persist. 

FLG mutations can lead to FA through 2 different mechanisms:

• Skin barrier dysfunction
• Subsequent inflammation caused by AD 

FLG mutations have an indirect effect on FA during childhood through AD. Therefore, children with both AD (eczema) and food sensitisation would be more likely to develop childhood asthma if they have the FLG mutation.

Dairy allergy

A dairy allergy, also known as cow’s milk allergy (CMA), is an allergic reaction induced by cow’s milk protein. It is distinct from lactose intolerance.  This allergy is common in infants and affects about 1 in 50 infants under one year old. ⁽⁵⁾ It is detected when breastfed infants start cow’s milk-based infant formula. 

Fortunately, half of these children will outgrow their allergy by the time they reach one year old, and most children are allergy-free by the age of three years old.  However, dairy allergy may be lifelong in a small minority of children. 

Dairy allergy can occur in two forms: Immediate reactions which are typically IgE-mediated (Type 1 reactions) or non-IgE-mediated. ⁽⁶⁾

IgE-Mediated CMA

Immediate allergic reactions to milk can happen within minutes of having small amounts of cow’s milk. The symptoms can range from mild (for most) to rare life-threatening whole-body allergic response called systemic anaphylaxis.

Symptoms of IgE-Mediated CMA

• Urticaria (hives)
• Angio-oedema
• Eczema exacerbation
• Vomiting
• Diarrhoea
• Bloody stools
• Gastro-oesophageal reflux
• Abdominal pain
• Rhinitis
• Irritability

Non-IgE-Mediated CMA

Delayed reactions to cow’s milk can be present for up to 72 hours after ingesting large volumes of milk. These reactions are generally not life-threatening. 

Symptoms of Non-IgE-Mediated CMA

• Gastro-oesophageal reflux
• Eczema exacerbation
• Diarrhoea/Constipation
• Bloody stools
• Feeding problems
• Irritability – Colicky 

Given the concerns over dairy allergy, studies have been carried out to examine whether the absence of dairy in young infants at high risk of allergy would reduce the subsequent development of allergic diseases like asthma. 

A study in South Wales reveals that rates of atopy and asthma were significantly higher in adulthood for those who avoided cow’s milk as infants.  This suggests that early and prolonged exposure to cow’s milk may be beneficial to avoiding dairy allergies later. ⁽⁷⁾

Asthma

AD is strongly associated with the development of asthma and allergic rhinitis (AR).  The relationship between AD and respiratory allergy is affected by AD severity. It is estimated that around 20% of children with mild AD develop asthma while over 60% with severe AD start having asthma. ⁽¹⁾

Hence, AD is associated with increased asthma severity, and also greater asthma persistence into adulthood. FLG mutations co with asthma development and severity in patients with AD.  Nevertheless, it is important to remember that not everyone with AD will develop asthma and not every patient with asthma has AD before that.

People with food allergies have a higher risk of developing asthma.  In a study in Philadelphia, the presence of FA was associated with the development of asthma and rhinitis. ⁽³⁾  About 35% of patients with food allergies in this study went on to develop asthma. Moreover, patients with multiple food allergies were at a much higher risk of developing asthma than those with just one food allergy.  Other studies also show the frequency of food sensitisation in children with asthma is higher than in the general population. ⁽⁸⁾

As a whole, asthma is made worse by food allergy more often in

• Younger children
• Children with AD
• Children with a higher total concentration of IgE 

However, food allergies do not immediately result in asthma conditions after ingestion. Urticaria or rash generally develops before the asthma symptoms. There is also an increased risk for wheezing and bronchial hyperreactivity (BHR).

Exclusion diet

Children who followed a diet without cow’s milk and egg had a significant improvement in lung function compared with those who had no dietary restrictions. Children with food allergies who went on an exclusion diet had better asthma control in 55 percent of the cases. ⁽⁸⁾

Summary

There is a correlation between dairy ingestion and asthma. However, dairy allergies are part of the wider picture of food allergies. The presence of one or more food allergies during childhood is a risk factor for the subsequent development of respiratory allergy and asthma. This is part of the natural history of allergic diseases known as the atopic march.