Diet and Microbiota in Health and Disease Symposium

I am so fortunate to live close to Boston’s Longwood Medical area, a worldrenowned medical and academic district, full of top notch hospitals and research centers, and home to Harvard Medical School. Last week, I attended Harvard Medical School’s division of nutrition 16th Postgraduate Nutrition Symposium.

This year, the title was Diet and Microbiota in Health and Disease.harvard symposium

To me, this area of research is utterly fascinating. Certainly for those of us with GI issues, understanding the role of gut microbes in relation to symptoms and overall health is paramount. But our gut microbes play a big role for all human beings, in health and in the advent of disease.

I have been following this research as closely as possible for the past 10 years…and what I can tell you is the more I learn about gut microbes, the more I realize the little we know about the magnitude of their role in our body.

The symposium covered some interesting topics such as: the role of breast milk in early intestinal colonization, role of food additives, particularly use of emulsifiers and their impact on the gut environment, high fiber diets, microbiota and allergic inflammation in the lungs, gut microbes in relationship to inflammatory bowel disease and onset of celiac disease, how the gut microbes impact circadian rhythm, and changes in the gut microbiome in obesity. Much of what was reviewed was looking at animal studies and is not ready for prime time in clinical practice with real people. This research is quite complicated and although we have expanded our knowledge significantly in the last 10 years, we have a very long way to go. Many of the studies evaluated colonic or fecal microbe levels rather than culture small bowel bacteria or bacteria that resides on the bowel wall. These microbes likely are even more important to our health but are a bit harder to access. As much as I would love to review everything, I will review only some of the highlights:

Emulsifiers commonly used in food products (to prevent the food from rotting!), Polysorbate 80 and Carboxymethycellulose are linked with metabolic syndrome, inflammatory bowel disease and small intestinal bacterial overgrowth.  This presentation was provided by Andrew Gewirtz, PhD from Georgia State University.  Although these food additives are generally recognized as safe (GRAS) by the FDA, they may induce changes in the gut environment, changing the lining of the GI tract, allowing a new niche for bacteria to ‘hang out’ and potentially cause damage and degradation of the protective mucus barrier.

The digestive tract is coated by a layer of mucus.  Mucus consists of proteins called mucins that functions to keep the lining lubricated and protected. Typically, the mucin is produced by goblet cells in our intestinal tract on a regular basis unless, this goblet cell function is disrupted by microbes and their toxins. This disruption can lead to degradation of the mucus layer. 

Here is a great recap of Dr. Gerwirtz’s work. And here is a mice study linking emulsifier use to bacterial overgrowth. Please note: Some links will be the abstract only as I do not have access to the entire article.

Another interesting talk was presented by Gary Huffnagle, PhD from University of Michigan.  His topic was the impact on microbiota, diet and allergic inflammation in the airways.  The lung was believed to be a microbe free organ for years but we now know that there are microbes that reside there normally. The bacteria in your mouth and nose is different than the bacteria that exist in the lungs. The lung’s lipid layer is a less favorable environment for bacteria to grow which differs greatly from the mucus lining of the GI tract. When inflamed, the lung environment changes and bacteria can find a niche to grow.  Dr. Huffnagle reported on this study showing  that dietary fermentable fiber content changed the composition of the gut and lung microbiota, in particular by altering the ratio of Firmicutes to Bacteroidetes. The gut microbiota metabolized the fiber, consequently increasing the concentration of circulating short-chain fatty acids (SCFAs). Mice fed a high-fiber diet had higher levels of SCFAs and were protected against allergic inflammation in the lung, whereas a low-fiber diet decreased levels of SCFAs and increased allergic airway disease.

Eric Martens, PhD, a researcher from University of Michigan, spoke about the role of polysaccharides and microbiota.  Remember FODMAPs are short chain carbohydrates while polysaccharides are L-O-N-G chain carbs. Dr. Marten spoke about how our gut bacteria have more carbohydrate digesting enzymes than we do.  There is some evidence that a diet low in fiber may contribute to the erosion of the mucus layer, which as I mentioned previously, normally provides a healthy barrier in our intestine. Depending on your genes and risk factors, some bacteria that help our body digest some starch and pectin, in susceptible individuals, can also induce colitis or inflammation in the large intestine. An important point: the onset of disease often involve your genetic make-up, changes in the environment (use of antibiotics, drugs, diet, etc) and gut microbes.  Genetic susceptibility for some health conditions often needs to be present for the disease state to emerge.

Lindsey Albenberg, DO from The Children’s Hospital in Philadelphia, spoke about diet and the intestinal microbiome and implications of disease, noting that gut microbe alterations have been linked with many diseases including: diabetes, heart disease, asthma, colon cancer and inflammatory bowel disease.  Dr. Albenberg noted that the less microbiome richness–meaning a reduced variety of microbes and their genes present– is associated with the diseased state. The Westernized diet is associated with a decline in microbiome richness.  Dr. Albenberg reviewed a study on vegans and omnivores (animal and plant eaters) revealed the 2 diets led to different composition of gut microbes, though the short chain fatty acids production, a  by product of fermentation, –surprisingly–remained similar. Gut microbial metabolites differed on the different diets. This brings up an important point, the presence of gut bacteria, amounts and types, is important but so is the type and amount of metabolites they produce. Some metabolites are toxic.

High fat diets–can alter bile composition and therefore,  can encourage the growth of pro-inflammatory gut microbes.  In one study, a diet rich in milk-derived saturated fat led to a rise in taurocholic acid which, in turn, stimulated the growth of certain gut bacteria. In genetically susceptible mice, one of these microbial species (Bilophila wadsworthia) triggered intestinal inflammation and colitis.

I had 4 not surprising but major take-a-ways from this conference:

  • Eat food created in nature, in it’s most natural state when possible.  Food products can contain potentially detrimental emulsifiers and additives, which in sensitive individuals, likely elevate risk of health consequences such as obesity or detrimental changes in our gut microbiata or intestinal environment.
  • Eat more and a variety of types of fiber found naturally in foods, as tolerated.
  • Gut microbes play a major role in our health and disease but the research is truly in its infancy and extremely complex.
  • More research looking beyond the bacteria found in stool is important (the researchers agreed on this) and culturing bacteria in our small bowel is equally important—if not, more important. There is a lack of studies looking at small bowel bacterial colonies.

Gut microbes and their impact on health is a global topic. Recently, Jane Muir, a dietitian and FODMAP researcher at Monash University was featured on the news in Australia with other scientist discussing this very topic.  Here is a clip from that segment.

Humans never truly dine alone–our diet is intimately linked with the functioning of the trillions of microbes that inhabit our gastrointestinal tract, the gut microbiota. ~Peter Turnbaugh

27 replies on “Diet and Microbiota in Health and Disease Symposium

  • Aging Ophelia

    Extremely interesting, and clearly some of this info, our average GP’s don’t necessarily have in their back pockets. Thanks for sharing!

    In the precursor to this article, you mentioned a connection with gut bacteria and sleep– I wonder if you could point me towards a helpful article/study. My sister is dealing with a terrible set of sleep interruption problems, and she has had some serious gut problems in the recent past– which makes me wonder if she is experiencing them in tandem. Her symptoms are not being treated that way, and some fresh info might help. Thanks, Mari

  • Susan Hook

    My daughter is expecting her second child. Her first child (breast fed) had terrible colic and gas. Would greatly appreciate any references or related info. on “the role of breast milk in early intestinal colonization” presentation you mention briefly above.

    • katescarlata

      Susan, I missed that talk unfortunately so don’t have any notes to share! But, interestingly a low FODMAP diet while breastfeeding has been shown in one small pilot study to reduce crying episodes in babies with colic. We know breast milk is best for the babies health when possible–in most cases. My first child had colic while I breast fed and next 2 children tolerated breast milk without a problem.

  • Marcia

    My gosh, thank you very much for taking the time to share some of the things you learned at the conference!!

    I’m not a medical professional and likely wouldn’t have come across or have access to this information for many years (until and if it comes into the mainstream). I sincerely appreciate your amazing generosity in sharing knowledge, new research, recipes, tales of your adventures, etc. :o)

  • dianne

    Polysorbate 80 is in IBgard! If it is so bad for the gut and microbiome, shouldn’t they not include it in a IBS aid? There is also yellow and green food coloring in IBgard. So unnecessary and not helpful for the purpose of the product.
    Thanks for all the info! I would have loved to have gone 🙂

    • Christine

      Good find! I didn’t even realize this. My doctor recently prescribed me with IBGard. It’s really helped with my symptoms but now I am considering finding another peppermint oil supplement without this ingredient. Thanks!

    • katescarlata

      Ugh! Drives me crazy when supplement manufacturers use these ingredients! Even probiotics with added color?! Why?? I did not know IBgard has polysorbate 80—thanks for bringing this to my attention. If you have been prescribed this supplement—call the company and request they remove it! Don’t sit back–be part of the solution! I will do the same!

      • Christine

        So true, Kate! Since IBGard has that ingredient, do you know of any other peppermint oil capsules that are suitable? I’ve seen quite a few out there but many have soybean oil in them- not sure if this is okay. Thanks!

  • shirley

    I have had severe IBS/D for several years. I finished a prescript of diflucan 200 mg “just in case” the neuropathy and redness of my feet and lower legs was a fungal infection; there was no change for the feet and legs and I do not have athletes foot/foot fungus. The change was with the IBS; I did not have diarrhea and other IBS/D symptoms during the course of the med. However, since finishing the diflucan a week ago, my IBS/D has returned again to make my life miserable. I do not think I can stay on the diflucan. Any ideas would be greatly appreciated. I am also on lotronex, 2x per day. Thank you for your time….sc

  • Nina

    Thank you so much for sharing, this is so fascinating indeed. I am currently reading Brain Maker and find it very interesting to read about the studies that are explained (even though I don’t understand how some conclusions are made, like why we all should cut out gluten since none of the studies so far mentioned in the book stated it and while various of them say that e.g. the microbiota of Africans is generally much more diverse and “better”, I don’t think Africans avoid gluten even though they probably eat much less than there is in a standard western diet). What are your thoughts on the book if I may ask?

    • katescarlata

      Nina, I am not convinced that gluten is the evil it is made out to be. I think in a compromised intestine–it might be an issue. But, I don’t recommend a universal adoption of a gluten free diet. We don’t need gluten. But, many of us don’t need to avoid it either.

  • Marisa | Marisa Moore Nutrition

    Thanks for sharing your takeaways, Kate. I am fascinated by the diet and microbiota connection and read everything I can get my eyes on these day. The new findings explain many of the mysteries of health and disease etiology but prompts so many questions at the same time!

    • katescarlata

      I agree Marisa! The more I know, the less I realize I know! It is an exciting time to be a dietitian! We know what we eat modifies our gut microbes–so we all need to keep abreast of the research to provide the best evidenced based health education to our patients. Having the solid background and experience in nutritional science makes the registered dietitian the BEST source of credible application of nutritional interventions, especially for those who suffer with GI disorders!

  • DrAmyG

    I was thrilled to read more about the microbiome research. As a childbirth professional, we’ve been aware of how much cesarean birth affects babies and outcomes, with c/s born babies having so many more health problems. But we didn’t know why; the microbiome is now considered to be the explanation. Some doctors are even taking vaginal swabs from the mother and wiping it on the infant’s nose and mouth in the hopes it will help make up for not passing through the birth canal. There’s an old joke, “Humans were invented for viruses to get from place to place.” I think the updated version is that humans exist to provide an environment for bacteria to live!

    • katescarlata

      I know Dr. Amy, it is so interesting! I have heard of the use of vaginal swabs in newborns born via c-section–so interesting!! I have heard that we have evolved as a vehicle for our gut microbes to live! Yowza!

  • Angela Brown

    I am on fodmap and paleo diet combining both. Pls give me some advice on probiotics or pre-biotics. I felt better when my GP-integrated medicine doctor had me taking Olive leaf extract and by buying the most reasonably priced probiotics I could find. Right now I am not taking anything as another DR. has asked me to do a faecal test costing $400.00. He has assured me hae has helped a lot of people to get healthy. I woill let you know the results of this test. Why is it on the fodmap diet I cannot tolerate sugar and that is what Dr. Sue Shepherd advocates. There is also a company in London, UK that will ship probiotics to you that has been tested by the university hospital in London. Sounds promising. Yours Sincereley, Angela Brown

  • Zach

    Great info thanks! I was a little confused on one aspect of the video. Jane Muir said the best foods to feed our gut were foods such as rye, barley, onions, garlic and legumes. I was under the impression that these were hi-FODMAP and we have therefore been avoiding them. Can you please clarify for me? Thanks

    • katescarlata

      Zach, the low FODMAP diet is a learning diet–not long term. Yes, we are removing highly fermentable foods to calm GI symptoms–and then adding back the healthy FODMAP rich foods to our personal tolerance–methodically–in an effort to pinpoint our personal dietary triggers. FODMAP sources: fructans and GOS found in rye, onions, garlic and legumes are BIG IBS triggers BUT also feed healthy gut microbes. So it’s all about finding YOUR personal tolerance. Small amounts of rye might work for you–and if it does—then eat it –and your healthy microbes will get some lunch too! 🙂

  • Margaret VanDyke

    This was a very interesting article, Kate and I have re-read all the questions and answers in other parts of your blogs, yet I am still desperating seeking an answer to my problem. I have had SIBO more than once and the latest doctor put me through a whole battery of tests (all negative) then finally prescribed rifaxim. After two weeks on two capsules a day( Why didn’t he follow guidelines and give me three!) I seemed to be free at last. No symptoms!! I asked you a couple of times if I should take probiotics but you have been very busy. I finally decided to take VSL3. Now the SIBO seems to have returned even though I have strictly followed the FODMAP diet. (after about 5 weeks or so of freedom) Here is my BIG question: when I belch (always frequent in the evening but no other time) I often sense a “blooming” in my nose of the smell of ammonia. Is this methane? Should I try to talk my doctor into another course of rifaxim, or can you suggest an herbal treatment like oregano? I have no idea how much or in what form that should be taken though I have read here and elsewhere that it can work. Can you please help me?

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