Hygiene Hypothesis revisited

Dr. Adrian Morris — Sun, 22 Jan 2012 18:54:43 +0000

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

Can worms prevent allergies?

Dr. Adrian Morris — Sat, 17 Oct 2009 12:09:25 +0000

The current epidemic of allergic disease seems to be in part related to living in a much cleaner more sterile environment together with a lack of parasitic worm infestations. This leads to an early switch in the infant’s immune systems to reacting in a more allergy prone (TH2) manner and less of a bacteria and viruses (TH1) targeting manner.

In a recent study published in Clinical and Experimental Allergy, investigators found that if mice had their gut infested with parasitic worms, they developed fewer food and airway allergies, but the parasites gave no protection from skin allergies. This is the first evidence that intestinal worms can actually modulate the immune system and “protect” against developing allergies.

A similar study on Vietnamese children showed that if they were treated to eradicate their parasitic gut hookworms, they became much more likely to develop house dust mite allergies and asthma.

Reference: Gastrointestinal nematode infection interferes with experimental allergic airway inflammation but not atopic dermatitis. Hartmann S, Schnoeller C, Dahten A et al. Clin Exp Allergy 2009 (39) 1585-1596.

http://news.bbc.co.uk/2/hi/health/8268584.stm

Dr. Adrian Morris of Surrey Allergy Clinic Tests and Treats allergies » hookworm

Hygiene Hypothesis revisited

Can worms prevent allergies?