• Sarah Greenfield, RD

Key Takeaways from the Harvard Microbiome Symposium

Arriving at Harvard was exactly how you would expect. It was historic, filled with intelligent people and I felt like I was part of something very important. On October 10th, Harvard Medical School brought together the top researchers in the field of the microbiome to share their key-findings and the latest research on the gut microbiome. Armed with my notepad and my intense curiosity, I sat in a lecture room for 2 days straight feverishly taking notes. I wanted to get every last ounce of info from this conference and bring back the juicy tidbits. As with most scientific presentations, the research is very specific and usually leads to the conclusion that more research needs to be done. However, after I had a couple days to process all the information, I compiled some key-takeaways from this conference that you can use in your life to improve your microbiome and overall health!

1. Our society has shifted from infectious disease to chronic disease

Over the past century, the medical profession has been working to create medications to combat infectious diseases. Polio, mumps, sepsis, pneumonia, etc once deadly, have all been able to be managed with modern medicine. We have seen huge advancements in vaccinations and antibiotics, which have helped save hundreds of millions of lives, but now we see a significant rise in chronic diseases like asthma, diabetes and obesity. In fact about 41% of the population have at least one chronic disease with half the population expected to have one or more by 2025. Many physicians have been trained with the philosophy to kill the "bad bugs" and keep things as sterile as possible. This presents a problem for our long-term health and the diversity of gut microbiome. Science is finding the microbiome plays a protective role when it comes to chronic disease. As we decrease our diversity through medications, stress and the standard American diet, we increase the likelihood of developing a chronic disease or having children that are more prone to developing chronic diseases. Managing chronic disease requires dietary changes, lifestyle changes, weight reduction and a more selective approach to taking medication.

Key Takeaway:

•A 5% reduction in body weight has been linked to medically significant health benefits, such as reducing risk factors of developing type 2 diabetes, and lowers your cholesterol levels.

•Medication + Lifestyle changes are more effective than just medication alone

2. Substrates may be more important than strains

What surprised me the most from the entire conference was the diversity of our gut and the strains of bacteria in our gut is important, but its not as important as what are gut bugs are making. Bacteria produce a number of beneficial compounds like short-chain-fatty-acids (SCFA), proteins, vitamins and even neurotransmitters which all impact different aspects of health. Charles Mackay, a professor at Monash University in Australia, found people with type 1 diabetes had lower levels of butyrate and acetate, SCFA produced by the gut microbiome. The higher the levels, the more protective they were against chronic disease.

Key Takeaway:

•Gut diversity can be protective against type 1 diabetes

•The more diverse your diet, the more diverse your gut!

•Increase the amount of fiber you are eating for better health outcomes (men: 30-38 grams per day, women: 25 grams).

3. Don't need to mega-dose on probiotics

Up until recently, I was under the impression that the higher the dose of a variety of probiotic strains, the better. I now understand that the variety is not as important as the outcome you want to achieve. Erika Isolauri, a pediatric physician in Finland found that giving mothers lactobacillus rhamnosis GG reduced the risk of their babies developing immune-mediated disease. In this case, taking a well studied strain and giving it to pregnant mothers improved the health outcomes of their babies. Check-out this great website that lists different strains of probiotics that are available in the US and their key health benefits.

Key Takeaway:

•Find a specific probiotic strain to address your specific health concern

•The interactions that probiotics have in our bodies are complex, including a probiotic in your daily routine could be beneficial

4. Celiac Disease and Food Allergies are on the Rise

The first case of celiac disease was documented in 1938 and has been on the rise. Since 1974 the incidence of celiac has been doubling every 15 years. Why do we see this increase in celiac and other food allergies? It was once theorized that there was a window of tolerance, if you introduce a new food to a baby when they are 4-6 months old, they will be less likely to have a reaction. We are finding that this is not necessarily true. It seems that the diversity of the gut and permeability, may play a bigger. Gut permeability can be caused by the standard American diet, stress, autoimmune predispositions and eating foods that your body is sensitive too, all of which are linked to inflammation. These are all factors that can contribute to a lack of diversity. The microbiome seems to be at the core of many health imbalances, especially auto-immune diseases.

Key Takeaway:

•An increase in food allergies may be linked to a decrease in gut microbiome diversity

•Eat a diet rich in whole foods, healthy fats, fiber to decrease inflammation and feed the gut microbiome

5. Our diets are sterile

This concept made me take a step back. Robert Hutkins, a food scientist, expert in fermentation, PHD and professor, made a comment that since he had been in Boston, he was only eating sterile foods. The problem with eating sterile foods is that we don't get any good bacteria in our bodies. We historically have been able to maintain gut diversity through consuming small amount of dirt and bacteria on produce, but now everything is sterilized. If you buy boxes or bags of pre-washed greens, these have been bleached and "washed 3 times" or our apples have been washed and coated in a wash layer to prevent bacteria that could cause spoiling. Pasteurization is another technique use to ensure bacterial strains are killed. I am not suggesting we go out and eat dirt, or only get unpasteurized foods, its important to be aware of how little exposure our produce has to the natural environment and how important it is to get bacteria in our diet. If you look back through history, many cultures had fermented foods a staple in their diets. Kimchi, kefir, sauerkraut, miso and borsht are all examples fermented foods. These help keep our immune system strong and our gut bacteria diverse, which as you now can decrease risk for chronic lifestyle diseases.

Key Takeaway:

•Include more fermented foods in your diet on a daily basis

•Buy product at farmers markets or in their least packaged and processed form

These were the most important pieces of information I learned while attending the Microbiome Symposium at Harvard Medical School. Of course I walked away with more questions than I had before, but I was very honored to be among some of the greatest minds working to understand the complex role the microbiome plays in our health. I look forward to all the emerging research in this field and will be keeping a close eye on new publications. I hope you will incorporate one thing you learned from this article into your daily life. Remember we are not searching for the perfect diet, we are searching to be better than we were the day before.


Sarah Greenfield RD, CSSD


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Studio City CA 91602 



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