The recent epidemic of allergic disease seen in developed countries has been difficult to explain. We have seen four-fold increases in allergic diseases such as asthma, rhinitis, eczema and food allergies. Changes in lifestyle and eating habits seem to be implicated and clean, sterile and infection-free “westernised” homes seem to be the probable trigger. One’s first year of life plays a pivotal role in allergic sensitisation and if an infant’s immature immune system is not correctly stimulated, it can transform into allergy-prone mode, particularly in children with a genetic predisposition to develop allergies (this is called atopy).

 Factors that seem to reduce the likelihood of developing allergies include:

• A home with 2 or more older siblings living in close proximity.
• Pet ownership (especially dogs & early exposure to animal farms)
• Exposure to parasite or hookworm infections (IgE was designed to combat worms).
• Exclusive breastfeeding for 4 months (confers immune protection).
• Early introduction of probiotic bacteria (acidophilus GG promotes gut immunity)
• Micro-bacteria in spoilt food and drinking water
• Dietary anti-oxidants, folate, fish oils and vitamins (such as Beta carotene)

 Factors that seem to promote allergic sensitisation include:

• Lack of older siblings (who carry germs that switch off allergies)
• Advancing parental age (aging genes predispose to allergy)
• Birth by Caesarian section (lacks exposure to protective vagina bacteria).
• Sterile Westernised homes (no germs to stimulate the immune system)
• Predominantly sterile indoor environment (no exposure to dirt )
• No household pets (faecal endotoxins & germs)
• Early use of paracetamol and antibiotics (alter immune responses)
• Lack sun exposure (lack of Vitamin D effects genes)
• Obesity and sedentary lifestyle (smaller lungs cause asthma).
• Parental indoor smoking (maternal during pregnancy and infancy).
• Withholding of potentially allergenic foods such as peanut and egg exposure in early infancy (4 months is better than 12 months).
• Diesel exhaust particles (make aero-allergens more potent)

 Reference:  Tan T, Ellis JA, Saffery R, Allen KJ. The role of genetics and environment in the rise of childhood food allergy. Clinical and Experimental Allergy 2012 (42) 20-29