The prevalence of food allergy has increased significantly over the years. In the U.S., United Kingdom, Canada and Australia, food allergies affect up to 8% of children and up to 5% of adults. Peanut allergy alone affects up to 5% of infants and young children. What is driving this epidemic is unclear, but there is likely an interplay between the environment and food allergy.
Decreased Exposure of Protective Environmental Factors
They hygiene hypothesis Hygiene Hypothesis and Increasing Allergies suggests decreased early life exposures to infectious agents (bacteria, parasites) leads to an imbalance in the immune system leading to more allergies. This can be attributed to overall improvements in public health and hygiene and an increased use of antibiotics for infectious diseases and anti-microbial exposure in soaps. Having less children in the family also leads to less microbial exposure with a potential of increased susceptibility to allergic diseases.
Urban lifestyles with lack of early life exposure to farming environments also have been identified as risk factors for allergy diseases, particularly asthma. How to prevent asthma and allergies in children
Other studies have shown that C-sections increase the risk of food allergies. C-section is associated with the abnormal bacterial colonization of a newborn’s gut in the absence of exposure to the protective bacteria in the birth canal. A pilot study introduced vaginal fluid at birth to infants delivered by C-section and it enriched the gut, oral and skin bacteria communities in infants, more studies are underway.
Vitamin D supplementation is another food allergy modifying factor. Lack of sunlight and less vitamin D, plays a role into increased allergies. A study showed that there were increased Epipen prescriptions in the northern US vs. the South, possibly related to decreased sun exposure which leads to less vitamin D, leading to more food allergies. Other studies were conflicting though.
The Western diet is characterized by the decreased consumption of omega-3 polyunsaturated acids (found in oily fish) and increased consumption of omega-6 polyunsaturated acids (found in margarine and vegetable oils). This has been shown to amplify the risk of allergies and asthma. Decreased consumption of dietary fibers has also been shown to play a role in increased allergies. Another study showed that cooked meats, oils and cheese that are abundant in Western diets induce inflammation.
The early introduction of foods, peanut, cow’s milk, egg and wheat into the infants diet was associated with decreased risk of allergy to these foods. When should we introduce allergenic foods in breast-fed infants?
Skin barrier impairment and increased skin water loss are risk factors for food allergy. Children with eczema are more susceptible. Results indicate that skin moisturizers in newborns can decrease rates of atopic dermatitis.
Increased Exposure to Negative Environmental Factors
Increased exposure to particulate matter, diesel exhaust particles, sulfur dioxide, nitric oxide and ozone has been associated with worsening asthma, airway reactivity and inflammation. Environmental tobacco smoke is the most significant indoor air pollutant.
Increased Exposure to Allergens Resulting from Global Warming
There are ways in which climate change could lead to changes in the prevalence of food allergy. Warmer temperatures and changes in carbon dioxide can lead to changes in production and allergenicity of pollen.
There seems to be a role of interplay between the environment and food allergy. Changes in the environment can lead to a rise of allergies in the world. This knowledge will enable mitigation of lifestyle and dietary changes, pollution and global warming.