Giving soon-to-be mothers and newborns doses of "good" bacteria may help prevent childhood allergies, new research suggests. Allergy experts say they offer the first good evidence that harmless bacteria can train infants' immune systems to resist allergic reactions.
Researchers in Finland used a type of bacteria found naturally in the gut -- called Lactobacillus GG (Lactobacillus rhamnosus), which is safe at an early age and effective in treatment of allergic inflammation and food allergy -- to try to prevent allergy development in at-risk infants.
Cultured bacteria that can potentially promote health are called probiotics.
Investigators gave a group of pregnant women probiotic capsules every day for a few weeks before their due dates. For 6 months after delivery, women who breast-fed continued on the probiotics, while bottle-fed infants were given the treatment directly. All of the babies were considered to be at high risk of developing allergies because a parent or sibling was affected.
By the age of 2 years, 35% of the children had developed allergic eczema, a condition in which the skin becomes irritated, red and itchy.
But children who had received probiotics were half as likely to develop the skin condition.
This cut in eczema risk is the most spectacular, single result to come out of studies on preventing allergic disease.
Exactly why friendly gut bacteria might protect against allergies is unclear, but the effect may be an "extension of the hygiene hypothesis."
This hypothesis holds that the worldwide growth in allergic disease is in part due to our increasingly sterile surroundings. When babies are exposed to germs early on, some experts suggest, their immune systems are steered toward infection-fighting mode -- and away from the tendency to overreact to normally benign substances. Support for this idea comes from studies showing that infants who have more colds and other infections have lower asthma rates later in life.
The results of this study suggest that intestine-dwelling bacteria may also play an important role in pushing the immune system away from allergic reactions.
The Lancet April 7, 2001;357:1076-1079
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