Australia has highest rate of food allergy sufferers, more research needed
Australia has the highest reported prevalence of food allergy in the world. This was a key issue addressed last week at the annual scientific meeting of the Australasian Society of Child Immunology.
Professor Johan Garssen of the Danone Research – Centre for Specialised Nutrition and Utrecht University –Department Immunopharmacology, Utrecht, the Netherlands, presented the latest research on possible ways to manage the problem of food allergies, which was a global phenomenon – although Australians appeared to be the most prevalent sufferers.
The prevalence of allergic diseases and asthma has increased dramatically over the past few decades, affecting an estimated 20% of the population in developed countries, especially children. The most dramatic increase in food allergy, earlier presentation and increasing persistence of disease was cows’ milk protein allergy with an estimated prevalence of 3% in the paediatric population.
Although the rates of allergic diseases in other regions of Asia are reported to be lower than in Australia, the rates of eczema, asthma and allergic rhinitis have already risen rapidly. Moreover, the Asian populations have been reported to be more susceptible to allergic disease in response to Western style environmental changes, as supported by evidence from immigration studies.
Professor Garssen considered a number of different hypotheses postulated to explain the increase in prevalence of allergic diseases in Australia and elsewhere. These were said to include a failure of immune tolerance, and environmental factors, such as microbial exposure (“hygiene hypothesis”), infections, diet and air pollution, both during pre-natal as well as during postnatal development. Several epidemiological studies support the hygiene hypothesis and have clearly shown that modifications of the pattern of microbial exposure and colonisation represent a critical factor underlying the rise in prevalence of atopic disorders.
Dietary factors have been implicated in the increased risk of allergic diseases and modern dietary changes appear to contribute to pro- inflammatory conditions.
Professor Garssen said that while it is well known that human milk is the best “immune” nutrition early in life (human milk can contribute to the immune defence of infants and accumulating evidence has indicated protective effects of breast feeding on different immunological diseases) as it contains a wide range of health protective compounds including carbohydrates, nucleotides, fatty acids, immunoglobulins, cytokines, immune cells, lysozyme, lactoferrin and other immune-modulatory factors.
Professor Garssen said an important group of immune-modulating compounds in human milk are non-digestible human milk oligosaccharides (HMOS). HMOS are known for their ability to selectively stimulate the growth and activity of bacteria that exert positive health effects. They have been described to promote the development of a tolerogenic environment in the gut, thereby reducing the risk of inappropriate immune responses like food allergy.
Although numerous medications exist to relieve allergic symptoms, no therapies have beendesigned to actually cure food allergy. For cows-milk protein allergy, hypoallergenic formulas with different extents of protein hydrolysation as well as amino acid-based formulas have been developed.
A major challenge in the fight against allergic diseases is the need for preventive measures early in life. The preventive use of cows- milk protein hydrolysates has been shown to be highly efficacious in reducing the incidence of allergy in high risk families.
The allergy protective effects of a specific mixture of prebiotic oligosaccharides, consisting of short chain galacto- oligosaccharides (scGOS) and long chain Polyfructose (lcPolyfructose) in a 9:1 ratio, have been demonstrated in both high and low risk families. This provided a basis for further exploring the role and underlying mechanisms of specific dietary factors as effective approaches to promote optimal immune development and reduce the prevalence of allergic diseases, although human milk was still the best.