26 October 2006

Probiotics boost innate immunity

A daily delayed-release tablet containing four probiotic strains boosted the innate immune system in healthy, non-elderly adults, says a pilot study.

A daily delayed-release tablet containing four probiotic strains boosted the innate immune system in healthy, non-elderly adults, says a pilot study.

“This study, which is one of the first to examine the effects of nutritional probiotic supplements on innate immunity in healthy adults, is an important step toward the investigation of their use in improving immune health and function,” wrote lead author Sheryl Berman in the journal Nutrition Research (Vol. 26, pp. 454-459).

The innate immune system refers to the immune system we are born with, and is the body’s first line of defence. The acquired immune system comes into action if a pathogen can get past the innate system and tailors the immune response specifically to deal with the invading organism.

Companies under pressure
The new research, by scientists at Bastyr University and the University of Washington in Washington State, is increasingly important as the current regulatory environment around the world means companies are under more and more pressure to provide evidence for the claims made on product labels.

In the US, there are no FDA-approved health claims for probiotics, but Danone's DanActiv is marketed for its immunity-enhancing properties, on the back of solid clinical evidence. Lifeway Foods, on the other hand, simply says its probiotic kefirs contain seven active ‘friendly' microorganisms.

Europe-wide health claims framework is currently in the works, but in the meantime the degree to which probiotics are marketed with solid health claims depends on the market. In the UK, for instance, Yakult is marketed for digestive health and Actimel for 'supporting the body's natural defenses'.

How the research was done
The new research used probiotic tablets formulated for delayed release by Nutraceutix, which also funded the study, and looks set to add to the science behind this form of probiotic. The four strains used were Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus salivarius, and Bifidobacterium bifidum and the tablets contained at least two billion organisms.

Ten healthy subjects were recruited (age range 24 to 54, five women) and given three probiotic tablets every day for eight weeks. Blood samples were taken to measure markers of innate immune function, including Natural Killer (NK) cell activity, phagocytes, neutrophils, and immunoglobulin A (IgA) levels.

The authors report a significant increase in the percentage of phagocytes (26 percent) and neutrophils (7 percent) after eight weeks of supplementation.

“These findings suggest the possibility that ingestion of these nutritional supplements by healthy individuals may help protect against bacterial and viral infections,” said Berman.

No enhancement of NK cell activity
However, no statistically significant enhancement of NK cell activity was observed, nor was there any change in IgA levels.

“Although the reasons for the lack of enhancing effects of probiotic supplementation on NK activity and salivary secretory IgA remain unclear, the baseline measurements for NK cell activity and salivary secretory IgA showed a high degree of within-volunteer variability,” said the researchers.

“Given the pilot nature of this study, it remains possible that probiotics do alter these immune parameters in healthy adults, but the small sample size limited our ability to observe an effect,” they said.

Taken overall, the researchers said the the results support the proposition that the four-species probiotic supplement does improve important aspects of the immune function in healthy individuals.

“Based on the preliminary findings of this study, conducting a larger, placebo-controlled, randomised clinical trial will be essential to determine if there is a difference in effects of these immune parameters over short- vs. long-term treatment periods,” concluded Berman. - (Decision News Media, October 2006)

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