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Science challenges remain in probiotics, gut health and immunity

Nutritional immunology professor Philip Calder, and Nutracon 2011 speaker, gives a sneak preview of his talk about emerging science in the digestive and immunity category of functional ingredients.

Philip Calder is a professor of nutritional immunology who will deliver a talk titled "Emerging Science: Assessment of Immune Function in Human Nutrition Trials" at Nutracon 2011. Calder teaches at the Institute of Human Nutrition within the School of Medicine at Southampton University, U.K.

Fi: What major developments have occurred in the understanding of immunity as it derives from metabolic activities in the gut?
PC: Up until relatively recently, the idea was that a change in gut microbiota, let’s say by consuming probiotics orally, had an impact on host immune function, but how that interaction between gut bacteria and the immune system came about was a bit of a black box. So I think the key developments have been a bit more in the nature of understanding that reaction. I think the nature of interaction is really twofold. One is that bacteria produce metabolites, chemicals and proteins that directly influence the host immune system. And two is that the bacteria might be able to directly link to – that is, bind to – cells of the host's immune system. So there's a physical interaction between bacteria and host.

Fi: How much of this understanding relates to the coding of the human genome?
PC: There’s a big drive to work out the genome of the gut microbiota. There are some big programs in that area. So that's more about understanding the gut bacteria themselves, and I think that’s been quite important. The human genome… in a way that’s less of an influence on the interaction we’re talking about. What’s more important has been some of the immunological advances: using good immunological tools to study the nature of interactions. Certainly sequencing the genome of the gut bacteria is a big step forward because then you have a better idea of what exactly you’re dealing with in the gut, which has been another bit of a black box, I think.

Fi: How much does the effective use of probiotics affect overall cellular inflammation?
PC: There are a couple of dilemmas here. In human studies it's very, very difficult to study the gut-associated immune system. And this is the direct site of the interaction of gut bacteria and the host. So what people are most commonly measuring in human studies are things that are circulating in the blood stream. And the blood stream is rather distant from the gut. One of the difficulties has been the inability to study the interaction at the site where it is occurring. The second is the question of whether there really are effects that can be demonstrated with probiotics. What is the immune benefit? Is there one? And is it strain specific, and so forth?

Fi: How strong is consumer acceptance of the efficacy of probiotics?
PC: Things like Actimel, Yakult, Activia and so forth, and the range of yogurtlike shots is increasing all the time. So I think there is a proportion of the population that accepts the idea. I don’t think the general consumer thinks that much about efficacy.  I think it's more holistic. They think these things are good for them, and they're tasty, so they buy them.

Fi: Health claims for probiotics have been taking a beating in the EFSA claims process. What's your view of how this process has worked?
PC: One of the problems has been that for many of the claims that have been put forward, the probiotic organisms have not been well characterized. The people wishing to make the claims can’t be 100 percent certain of the bacterium that the claim is based on. So a lot of the claims have fallen by the wayside for that reason.

But the ones that got beyond that have fallen by the wayside for other reasons. At the moment, the EFSA panel has taken the stance that simply changing the profile of gut bacteria is not in itself a health benefit, although they do accept a benefit if there is a particular reduction in the numbers of certain pathogenic bacteria. In other words, reducing pathogenic bacteria would be seen as a good thing, and altering other types of bacteria is neither here nor there. So this is the second stumbling block for both pre- and probiotics – the target of the gut microbiota isn’t that well accepted.

Then the third stumbling block: If just changing gut microbiota is not seen as a health benefit – how do you demonstrate a health benefit beyond that, which is where the effect on immunity might come into play. At the moment I don’t think there are any positive opinions based on dossiers around immune function and pre- and probiotics. Whatever evidence that has been produced has not been deemed by the panel as having been sufficient.

Fi: Is that having a chilling effect on this side of the Atlantic?
PC: This is a process that has started de novo a matter of a couple of years ago.  Because this is something that is relatively new, people have been watching it to see what happens. That’s why, almost surprisingly, it seems that the FDA and regulators in Asia and probably in Australia, have been looking very closely at what’s been happening with EFSA. It is possible that the outcome of the EFSA activities will have some influence on regulatory bodies outside of Europe. 

Fi: It seems as if health claims connected to probiotics are getting more vague. Is there a way to support health claims with science?
PC: Serious industry quite rightly does support this idea that science is important and that claims must be scientifically based. But I think in this area there is a bit of a mismatch between a reasonable amount of scientific endeavor and the poor response from the EFSA panel. Maybe if there were some positive opinions every now and then, people in industry would have a little bit more confidence.

Now in other areas, of course, there have been a number of positive opinions. Things like plant sterols and stanols and cholesterol lowering, for example. Omega-3 fatty acids and blood pressure, omega-3 fatty acids and triglyceride lowering – these have all had positive opinions. And the science in those areas actually is very strong; you have clearly defined biomarkers and you have plenty of studies evaluating the nutrient or the food against those biomarkers. So the system works [in that case]. In the gut health and immune area the biomarkers are less well described. So if you haven't got a well-described set of biomarkers it’s difficult to demonstrate an effect. 

Fi: What's your daily supplement regime?
PC: I do not use supplements. I eat plenty of fruit, vegetables, grains and oily fish.

Nutracon 2011 Highlights: Digestive Health & Immunity Track

Track chair: Gretchen Vannice, MS, RD, president, Omega 3 RD Nutrition Consulting

Get a healthy dose of probiotics in this Nutracon 2011 track, supplemented with several other gut health sessions such as evaluating an immune health ingredient, and much more. Nutracon is March 9-10, 2011, in Anaheim, Calif., co-located with SupplyExpo and Natural Products Expo West.

  • Robert Martindale, MD, Ph.D., on probiotics. Find out if probiotics are a fad or if the friendly bacteria are worth their clout in Martindale's talk titled "Emerging Science: Probiotics: Food Fad or Bacterial Therapy?"
  • Todd Runestad chairs a probiotics panel. Panelists, including Armin Salmen of Next Foods, will discuss how to position your probiotic.
  • Ewa Hudson on probiotic and prebiotic trends. Hudson is research program manager for the global Health and Wellness industry at Euromonitor International.
  • Science panel. Join a panel of doctors and scientists for "Emerging Science: The Importance of the Gut to Inflammation." This talk will include discussion about the use of proteins and peptides in products to reduce inflammation.
  • Regulatory roundtable. Get your questions answered on immunity claims with speakers Claudia Lewis of Venable, LLC; CRN CEO Steve Mister and Michelle Rusk, FTC senior staff attorney.
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