Scientist - News - 15-05-2009:

Probiotics against Mexican flu?
Beintema, Nienke
also in German, click

Some online news sources are expressing hope that probiotics may help to prevent Mexican flu (also known as swine flu). They all refer to the same study published in March that suggested that B. coagulans prevents infection with an influenza A strain. The world should not hold its breath for this, says a Dutch expert.

Mexican flu is a hot topic in the media worldwide. Rumours and speculations about this mysterious virus, however, are circulating at a much greater intensity than the virus itself. Among the suggested ‘saviours of humanity’ are probiotics. Some internet sources refer to the general, proven immune-boosting potential of probiotics. Others, however, such as PR Newswire (the self-acclaimed ‘global leader in news and information distribution services for professional communicators’), refer to a study published in the March issue of the journal Postgraduate Medicine. This study concludes that Bacillus coagulans, marketed as ‘Sustenex’ by Ganeden Biotech, significantly reduces the risk of infection with influenza A (H3N2 Texas strain). PR Newswire and others suggest that this is good news in view of the current pandemic threat posed by Mexican flu.

Lacks transparency
A premature conclusion, according to dr. Ger T. Rijkers, medical immunologist at the University Medical Center Utrecht (The Netherlands). "First of all, in my opinion this article in Postgraduate Medicine should never have been published in the first place," he states. "The author is head of a contract-research company that was hired by Ganeden Biotech to perform this study. However, the article doesn’t mention any conflict of interest. To me that is highly suspicious. Secondly, I am not at all impressed by the results. The whole study lacks any form of transparency."
The study involved in vitro experiments with blood samples taken from ten individuals. Their blood cells were cultured and the levels of two immune marker molecules were measured before and after viral challenge: interferon-γ and TNF-α. The former, explains Rijkers, is most important as a marker for immunological defence; however, only the latter showed a significant increase after a viral challenge – but only of one of the tested viruses: H3N2. "For H1N1, the subtype that the recent virus belongs to, there was no significant difference," indicates Rijkers. "Moreover, the results were presented in a way that does not allow to see the actual data. You’d expect four columns in a table of results: the value in question before and after the viral challenge in the blood sample taken before administration of the probiotics and the same afterwards. However, only one column was presented indicating the differences. All in all this seems very obscure to me – let alone that the results can be extrapolated to Mexican flu."

Overrated
Rijkers does confirm the earlier results of other studies that suggested that probiotics can reduce the duration of – albeit not prevent – episodes of the common cold during the winter season. This condition is mostly caused by rhinovirus, not influenza. Given the proven effect of probiotics on the immune system – they activate so-called dendritic cells, which in turn promote the activity of the immune system’s T helper cells – he does not preclude a potential effect of probiotics on influenza viruses, including Mexican flu. However, he cautions against premature conclusions. "Apart from that," he notes, "I believe the threat of Mexican flu is highly overrated. Virologists make it seem as if man is completely defenceless against this virus. They seem to underestimate the potential of our immune system."

More information:
Original article in Postgraduate Medicine (March 2009)
(Click on the final link in the ‘Fast track’ section in the column on the left)
Wishful reporting on PR Newswire
Wishful reporting on Yahoo’s news site