Dr Kristin Wickens
Dr Kristin Wickens

10 April 2013

The health benefits of eating yoghurt have been known for centuries in some cultures but only in recent years have researchers really begun to understand the benefits of probiotics, especially in terms of their positive effects on allergic diseases.

New Zealand has one of the highest rates of asthma and allergies in the world, making finding some form of prevention especially important. Research funded by the HRC and co funded by Fonterra shows that a probiotic involving a bacterium named Lactobacillus rhamnosus HN001 can protect against the development of eczema in children by the age of two years and through to a follow-up at four years.

Dr Kristin Wickens, a principal investigator for the Wellington Asthma Research Group at the University of Otago's Wellington School of Medicine and Health Sciences, says the double-blind, placebo-controlled study, involving 474 infants at risk of allergic disease, tested two different probiotics supplied by Fonterra.

The researchers found that L. rhamnosus HN001 reduced eczema prevalance by a half at the age of two years but the other probiotic had no effect on eczema.

“We found that the effect on eczema persisted at four years, that is two years after they stopped the probiotics or placebo, suggesting that when they stopped taking the probiotic they didn't get a rebound effect where eczema occurred. In other words, it’s been shown to have quite long-term benefits on the children.”

Dr Wickens says that although it reduces the rate of eczema by a hugely beneficial 50 per cent, eczema is just one allergic disease. Ultimately they want to address the underlying immunity of the child to prevent what she calls the ‘allergic march’, where the allergic predisposition to eczema may also put the child at risk of developing asthma and allergic rhinitis (hayfever) as the child ages.

“We haven't been able to show yet whether it has an effect on the underlying allergic predisposition of the child. In fact by age four years our research showed only a small protective effective against that underlying allergic state that puts children at risk of all allergic diseases, including eczema, asthma hayfever and food allergy.”

The research team is currently preparing results from its six year follow-up for publication.

Dr Wickens says the probiotic approach sits within what is called the ‘hygiene hypothesis’.

“The idea is that since the middle of last century, people have been exposed to much more hygienic conditions.

“We have a lot less infection around because of antibiotics, and we clean our households with antibacterial products, so we’re wiping out all the bacteria in our environment. With less exposure to bacteria our immune system is deviating towards the allergy arm and we're getting more allergies,” she says.

“Probiotics are good bacteria with health benefits. They have potential to stimulate the Th1 arm of the immune system providing a healthy balanced immune profile. Without this stimulation the allergy Th2 arm becomes dominant.“

Dr Wickens says they are now wanting to look at the effect on the infant of the mother taking the probiotic from early pregnancy. Compared with the original study where the mother started the study capsule at 35 weeks gestation, an early intervention may have greater potential to alter the developing immune system of the foetus with long-term benefits for the protection against underlying allergic predisposition and allergic disease.

From the original study, they have limited data from mother’s breast milk and cord blood showing that if the mother has taken the probiotic it is associated with an increase in the level of Th1 cytokines that are protective of allergy. Cytokines are signalling molecules that help orchestrate complex bodily functions such as fighting infection (Th1 cytokines) or in the case of allergy (Th2 cytokines) become overactive and directed to the wrong things.

“Through their effect on cytokines, there is evidence that probiotics can influence the immune system and provide the protection that is necessary to stop allergies developing.”

“With the exception of one other study from Finland, all other probiotic intervention studies have started the intervention at about 35 weeks’ gestation, but for this new study we are starting at between 14 and 16 weeks. Hopefully this way we can influence the underlying allergic status of the child.”

“Our main aim with this new study would be to influence that whole spectrum of diseases from eczema and food allergy, to asthma and hayfever.”

They are currently recruiting women in Auckland and Wellington for the new study and are keen to get more participants. She says that this time the supplement is being taken by the mothers only (not the babies) for six months post-birth if breast feeding, which makes it a far easier intervention. The probiotic supplement used in the study is stronger than those available commercially, which makes it more likely to be effective.

The original two-year study was published in the Journal of Allergy & Clinical Immunology (October 2008) while the four-year follow-up was published online in Clinical & Experimental Allergy (July 2012).