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Probiotics Come with Bold Health Claims, but the Science is Shaky

posted by martyb on Wednesday January 27 2016, @03:36PM   Printer-friendly
from the avoid-the-amateur-biotics dept.

AndyTheAbsurd writes:

The "good bacteria," or probiotics, that fill the pomegranate drink are everywhere these days, in pills and powders marketed as super supplements. Probiotics are said to improve digestive and immune health. They're touted as potential treatments for conditions ranging from inflammatory bowel disease to eczema to tooth decay. Some marketing campaigns even hint that they can prevent the flu.

Scientific evidence, however, does not necessarily support those claims.

Studies in rodents and small groups of humans point to possible health benefits of consuming probiotics. But there have been only a few large human trials — in large part because Food and Drug Administration rules have dissuaded food companies and federally funded researchers from conducting the types of studies that could confirm, or refute, the proposed benefits of consuming "good" microbes.

http://www.statnews.com/2016/01/21/probiotics-shaky-science/

Original Submission

 
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  • (Score: 2) by quixote on Wednesday January 27 2016, @08:23PM

    by quixote (4355) on Wednesday January 27 2016, @08:23PM (#295532)

    If they aren't, you have bigger problems than bad bacterial flora in your large intestine.

    What affects the ecology of bacteria in the colon is the contents of the colon. That's composed of undigested food such as different kinds of fiber, the breakdown products of digestion, digestive acids from the liver, breakdown products from the bacteria living there, and so on.

    The reason yoghurt and sauerkraut and fibrous food help is not because of the bacteria they contain. Those (you hope!) got killed in the stomach. They help because by the time you've finished digesting them, what's passing through the large intestine is conducive to the growth of bacteria associated with good health.

    Changing diet can change intestinal ecology drastically, so, yes, what you eat matters for that. But not in the sense that eating, say, Lactobacillus acidophilus somehow makes it all the way to the colon and starts a "good" colony.

    It is possible to introduce specific strains of bacteria to the colon, but it's done from the other end and is called a fecal transplant. And, yes, there's very interesting research coming out showing that changing intestinal ecology can have far-reaching effects on health and disease.

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  • (Score: 2) by takyon on Wednesday January 27 2016, @08:36PM

    by takyon (881) <takyonNO@SPAMsoylentnews.org> on Wednesday January 27 2016, @08:36PM (#295536) Journal

    Are you sure Lactobacillus can't survive the stomach? They do excrete acid after all.

    Well, I looked it up and it turns out THEY CAN:

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1489325/ [nih.gov]

    Whether Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus can be recovered after passage through the human gut was tested by feeding 20 healthy volunteers commercial yogurt. Yogurt bacteria were found in human feces, suggesting that they can survive transit in the gastrointestinal tract.

    http://ajcn.nutrition.org/content/73/2/399s.full [nutrition.org]

    Bifidobacteria and lactobacilli are purportedly beneficial to human health and are called probiotics. Their survival during passage through the human gut, when administered in fermented milk products, has been investigated intensely in recent years. Well-controlled, small-scale studies on diarrhea in both adults and infants have shown that probiotics are beneficial and that they survive in sufficient numbers to affect gut microbial metabolism. Survival rates have been estimated at 20–40% for selected strains, the main obstacles to survival being gastric acidity and the action of bile salts. Although it is believed that the maximum probiotic effect can be achieved if the organisms adhere to intestinal mucosal cells, there is no evidence that exogenously administered probiotics do adhere to the mucosal cells. Instead, they seem to pass into the feces without having adhered or multiplied. Thus, to obtain a continuous exogenous probiotic effect, the probiotic culture must be ingested continually.

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1151822/ [nih.gov]

    Probiotics must survive in the acidic gastric environment if they are to reach the small intestine and colonize the host, thereby imparting their benefits. Lactobacillus species are considered intrinsically resistant to acid (51).

    [...] The increased survival of probiotic lactobacilli in acidic conditions in the presence of glucose has been reported previously (7). However, the mechanisms involved were not studied. In addition, it has been reported that lactic acid bacteria are capable of metabolizing glucose at low pH, albeit at lower rates (29, 54). The aims of this study were to evaluate the effect of glucose on L. rhamnosus GG survival in simulated gastric juice, to compare the protective effect of glucose on L. rhamnosus GG survival at low pH with that for other probiotic lactobacilli, and to elucidate the mechanisms responsible for the protective effect of glucose in acidic conditions.

    See bolded portion and compare to:

    The reason yoghurt and sauerkraut and fibrous food help is not because of the bacteria they contain. Those (you hope!) got killed in the stomach.

    I was about to say that effects could be seen before anything reaches the stomach. For example, bacteria in the mouth affect tooth decay, and tooth decay is linked with heart disease (I'm not sure about the causality).

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    • (Score: 0) by Anonymous Coward on Wednesday January 27 2016, @09:33PM

      by Anonymous Coward on Wednesday January 27 2016, @09:33PM (#295578)

      Just because some bacteria is good for your gut doesn't mean it's also good for your teeth.

      • (Score: 2) by takyon on Wednesday January 27 2016, @09:56PM

        by takyon (881) <takyonNO@SPAMsoylentnews.org> on Wednesday January 27 2016, @09:56PM (#295588) Journal

        Every part of your body has different kinds of bacteria living on it. The microbiome is necessarily a complex subject

        It means that the introduction of certain bacteria could be considered an oral health treatment.

        On the subject of bacteria good for your gut being good for your teeth, I found this:

        http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897872/ [nih.gov]

        Several studies suggest that consumption of products containing probiotic lactobacilli or bifidobacteria could reduce the number of mutans streptococci in saliva.32–40 The tendency toward a decreased number of mutans streptococci in the saliva seems to be independent of the product or strain used; however, such effect has not been observed in all studies.41 The discrepancies between results cannot be explained by only the use of different probiotic strains, as different results have also been obtained using the same strains.

        [...] The first studies of the use of probiotics for enhancing oral health were for the treatment of periodontal inflammation.43 Patients with various periodontal diseases, gingivitis, periodontitis, and pregnancy gingivitis, were locally treated with a culture supernatant of a L. acidophilus strain. Significant recovery was reported for almost every patient. There has been significant interest in using probiotics in treatment of periodontal disease recently, too. The probiotic strains used in these studies include L. reuteri strains, L. brevis (CD2), L. casei Shirota, L. salivarius WB21, and Bacillus subtilis. L. reuteri and L. brevis have improved gingival health, as measured by decreased gum bleeding.

        [...] The interest in oral probiotics has been growing during the last decades. Most of the studies have been conducted with probiotic strains originally suggested for gut health; however, it is important to realize that each of the suggested health benefits should be studied for each bacterial strain individually. Thus, a probiotic bacterium in the mouth is not necessarily an oral probiotic. Furthermore, it is quite possible that the same species are not optimal for all oral health purposes; e.g., different properties might be desired in respect to dental and gingival health.

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    • (Score: 2) by quixote on Friday January 29 2016, @11:18PM

      by quixote (4355) on Friday January 29 2016, @11:18PM (#296749)

      Interesting! And good news for those of us trying to improve our large intestine bacteria.

      It is still true, though, that the largest effect on those bacteria is the environment they're given. If your diet is meat+sugar, just as an extreme example, the occasional dose of probiotics won't help much. If you have one of those healthy Mediterranean diets they're always on about, you'd be very likely to have good intestinal flora without any added probiotics. (Although yoghurt is or can be part of that diet, so there's that.)

      Anyway, cool to learn something new with good links to sources. :D