Probiotics—”good” bacteria found in healthy mammals’ intestinal tracts—help regulate digestion and control the harm done by infectious bacteria and yeasts. New research shows that giving probiotics to pregnant women and their babies is safe and may prevent infections. However, it’s unlikely that they can curb the recent increase in childhood allergies.
Lower exposure to bacteria in early childhood may stop the immune system from developing as it should. Allergic children also often have different types of bacteria in their intestines, specifically, less lactobacilli and bifidobacteria.
A team from the University Central Hospital of Helsinki, Finland decided to investigate whether probiotic supplements could add these missing bacteria.
The researchers gave either a probiotic mixture (2 lactobacilli, bifidobacteria, and propionibacteria) or a placebo at random to 1,223 mothers whose infants were thought to be at high risk of allergies, for the last month of their pregnancy. Once born, their babies were given the same mixture plus a prebiotic galacto-oligosaccharide from birth until they reached six months.
At five years old, the children were examined for symptoms of eczema, food allergy, allergic rhinitis (hay fever), and asthma. The probiotics did not protect children from allergies, except those who had been born by Caesarean section. This group had a 53 percent lower chance of developing an allergic disease.
The study is published in the Journal of Allergy and Clinical Immunology.
Researcher Dr. Mikael Kuitunen said that “it is possible that stronger and longer stimulation of the infant immune system possibly by varying the strains of bacteria, may result in better allergy-preventive effects.”
The same team previously found a beneficial effect of probiotics and prebiotics against food allergy and eczema, but these new results cast doubt on the earlier findings. They have also investigated the long-term safety of giving probiotic and prebiotic treatment to newborn infants, and its impact on infection rates. They say that “live probiotic bacteria and dietary prebiotic oligosaccharides (together termed synbiotics) are increasingly are being used in infancy, but evidence of long-term safety is lacking.”
In their study, carried out between November 2000 and March 2003, 1,018 pregnant women whose babies were deemed to be at high risk for allergy were randomly given either a mixture of four probiotics or placebo for four weeks before delivery. Their infants received the same probiotics plus prebiotic, or placebo, every day for the first six months.
“Infants in both groups grew normally,” report the experts in the journal Pediatrics. There were no differences in mortality rates or feeding-related behaviors such as colic. Babies taking the synbiotics needed slightly fewer courses of antibiotics than those on placebo, and suffered fewer infections, an average of 3.7 compared with 4.2.
“Feeding synbiotics to newborn infants was safe and seemed to increase resistance to respiratory infections during the first two years of life,” the researchers concluded.
Despite mixed findings, positive results in the field of pre- and probiotics have led to enthusiasm in the scientific community, the food industry, and among the public.
Dr. Kuitunen says that allergic disorders are generally caused by an overreaction of the immune system in response to “antigens” in the environment. Dietary approaches to reducing the risk of allergies or controlling symptoms “have not been satisfactory regarding long-term prevention, and new approaches are urgently needed,” he writes. This realization has led to new ideas based on the consumption of beneficial live probiotic microorganisms.
Basically, the aims are to restrict the growth of damaging microorganisms, to strengthen the gut’s defenses, and to stop “hypersensitivity reactions.” Probiotics of the groups Lactobacillus and Bifidobacterium are most often used. They have been shown to regulate inflammation and oversee “the development of the immune system during the critical period of life when these functions are immature and inexperienced and the risk of allergic disease is heightened,” says Dr. Kuitunen.
The action of each probiotic strain differs, as each strain is a unique organism itself with specific properties. A combination is probably needed to “counter the plethora of allergic disease,” especially as every individual will have a different gut mixture to start with. At present, experts are trying to identify specific strains with anti-allergenic potential, as well as the dietary question of how different foods and food combinations can interact and support these strains of “friendly bacteria.”
Kuitunen, M. et al. Probiotics prevent IgE-associated allergy until age 5 years in cesarean-delivered children but not in the total cohort. The Journal of Allergy and Clinical Immunology, Vol. 123, February 2009, pp. 335-41.
Kukkonen, K. et al. Long-term safety and impact on infection rates of postnatal probiotic and prebiotic (synbiotic) treatment: randomized, double-blind, placebo-controlled trial. Pediatrics, Vol. 122, July 2008, pp. 8-12.
Isolauri, E. et al. Probiotics: use in allergic disorders: a Nutrition, Allergy, Mucosal Immunology, and Intestinal Microbiota (NAMI) Research Group Report. The Journal of Clinical Gastroenterology, Vol. 42, July 2008, pp. 91-96.