Q: Angiogenesis function? This is new to me. Are there are references you can point me/us to? 

Franks I. Gut microbes might promote intestinal angiogenesis. Nat Rev Gastroenterol Hepatol. 2013;10(3). doi: https://doi.org/10.1038/nrgastro.2012.227. 

Hassan M, Moghadamrad S, Sorribas M et al. Paneth cells promote angiogenesis and regulate portal hypertension in response to microbial signals. J Hepatol. 2020;73(3):628-39. 

Q: Is there a recommended test for to assessing dysbiosis?  

The most direct measurement for now would be to have a GI map done on a stool sample.    

Q: Does wine (red/white/rosé) count as a fermented food/beverage?  

It’s more likely that the polyphenols in red wine contribute to the growth of beneficial bacteria as the benefits are seen in alcohol-free wine as well. Excessive alcohol consumption has also been found to break down the tight junctions and damage the intestinal epithelium.    

Q: Dr Osterberg discussed the negative effects of strenuous exercise and overtraining on the gut. What amount of overexercising could cause this effect?  

This is likely very dependent upon the individual’s fitness and training environment, diet, lifestyle, etc.  Some studies say that “overexercising” is anything over 60 minutes of moderate exercise, but the athletes in many of the studies I mentioned did much more than that, as do most elite athletes.  

Q: Thank you for your presentation! Can you please comment on “leaky gut” and lectin-containing foods? Many athletes are leaning on a plant-based intake and they are getting protein and fiber from lentils and legumes, but Internet info raises concerns about leaky gut.  

There may be some genetically susceptible people for whom lectins can cause an inflammatory reaction. I believe this is an autoimmune response, and I don’t have statistics on the prevalence of this, but if it’s like other autoimmune conditions, it would only affect a small number of people.  

Q: what would you say should be our one to two takeaways to teach our clients?  

Eat a wide variety of plant foods. Exercise regularly. Find ways to reduce psychological stress. 

Q: Are you providing a rationale for carbs? What does this mean for the keto people? 

Carbohydrate from plants is very important for health and supported by many epidemiological studies. A ketogenic diet reduces microbial diversity. For some people, especially those with seizure disorders, a ketogenic diet can improve symptoms, but it still reduces microbial diversity. 

Q: Can you recommend a reliable fiber-screener tool to use with clients?  

I don’t know of one, sorry. 

Q: Would you please explain the difference between prebiotics and probiotics?  

Prebiotics are fibers from plants that support the growth of beneficial bacteria in the gut. Probiotics are live bacteria that are ingested. 

Q: Are you aware of any literature addressing how long it takes to “change” or “shift” a person’s microbiota after changing their diet? Curious as to length of that process within the gut. 

Populations can shift very quickly — in as little as 24 hours. Most studies are short term, but the changes should last for as long as the dietary change is in effect.   

Q: Realistically, how easy/effective is the process of adding to/getting your micro biome and gut health back to normative levels after years of bad diet and overusing antibiotics?  

It’s a great question. A dietary change (from say Western to plant-based) would probably change microbial communities very quickly. The antibiotic piece is difficult to predict as it probably requires more than a “shift” but rather a repopulation.   

Q: Meditation and gut health — could you please provide sources?  

I didn’t have one when I made the comment — just a suggestion for reducing stress. But see below: 

Jia W, Zhen J, Liu A et al. Long-term vegan meditation improved human gut microbiota. Evid Based Complement Alternat Med. 2020. doi: 10.1155/2020/9517897. 

Q: With so much research proving a plant-based diet’s benefits for the gut, why would you say in your talk today that you’re not promoting the diet?  

I fully support and would recommend a plant-based diet. I think my comment was that I wasn’t necessarily promoting a vegetarian or vegan diet. An omnivorous diet can also be healthy as the study I cited showed poultry, fish and low-fat cheese were also strongly associated with a healthy gut microbiota.  

Q: How do you see the role of fermented food helping gut health?  

Eating fermented food is essentially eating food that contains probiotics. When food is fermented under the right conditions, an acidic environment is created, allowing for the growth of beneficial bacteria (many Lactobacillus species) and the inhibition of pathogenic bacteria. 

Q: Any caution regarding alcohol intake on gut health?  

Excessive alcohol intake can increase gut permeability and damage epithelial cells.  

Q: Do you have a theory for why the marathoners had that strain of microbiota spike so greatly after the marathon vs. during training? Was the exertion that much greater on race day, perhaps?  

It’s a great question! It may have been related to exertion or maybe fueling … or lack thereof?   

Q: Has there been any study comparing gut health and performance of athletes with plant-based diets (vegan & vegetarian) vs. those who consume meat?  

There are many studies comparing plant-based to omnivores in humans, but nothing that measured performance (that I know of). 

Q: Are there any good studies with recommendations for fermented food intake? Including frequency and amount? 

I don’t know of any specific recommendations.   

Cold weather training doesn’t place the same thermal stress on the gut. Blood flow to the gut is more easily maintained because it doesn’t have to be diverted to the skin for cooling. 

Q: Do supplemental probiotics need to be taken indefinitely, or do they eventually colonize in the body?  

It’s a great question. I’m not sure if it’s ever a case that they colonize, but I do think they help balance total communities in favor of beneficial bacteria. I think the amount of time you would need to take them would depend on the reason they’re being taken (diarrhea, food intolerance, immune function, etc.). 

Q: Does sodium bicarbonate supplementation impact gut microbiota?  

Great question! My guess is that most sodium bicarbonate is absorbed in the small intestine, so it would not impact microbiota to a large extent. 

Q: You discussed the Veillonella rat study, increasing run time in rats. There are now some probiotics that include this bacteria. Could taking these pre race improve performance? 

Interesting! I didn’t know this, but I can’t wait to see if supplementation helps!   

Q: You mentioned that high cardiorespiratory fitness and more intense exercise increases bacterial diversity. How is intense exercise different than exhaustive exercise? And how do we determine helpful vs. harmful levels of exercise?  

Intense exercise is exercise that is done at a high percentage of VO2 max. Exhaustive exercise is generally defined as exercise that continues until a certain minimum % VO2 max or max wattage can no longer be maintained. Intense exercise doesn’t have to be exhaustive. As for your second question, I don’t have a good answer in the context of gut microbiota. It’s likely multifactorial and based on many other factors in any individual athlete’s life, including diet, fitness, lifestyle, etc. 

Q: Toward the end you mentioned avoiding cutting blood flow to the gut? How would one be cutting circulation? 

Intense exercise, especially exercise in the heat, diverts blood flow away from the gut and to muscles (for fuel and oxygen) and skin (for cooling). This decreases blood flow to the gut and can damage the epithelium and increase the likelihood of gut permeability. 

Q: How would you compare “themed” diets like keto, paleo, etc. with their effect on gut health? 

Studies would suggest that the more plants and fiber the diet contains, more microbial diversity would be present in the gut. 

Q: What is a good way to determine if the gut is irritated by consumption of certain food? Should that food be cut out for good?  

There are certainly conditions that call for cutting out the food for good (celiac disease, for example). For some people, eliminating foods that contain certain components (FODMAPs) can help ameliorate symptoms of GI distress. When a person is in dysbiosis, they may respond to food components differently than they would if their gut is healthy. In general, I would recommend keeping as many plants in the diet as possible.  

Q: Comments on fecal transplants?  

Definitely works for certain conditions (C. diff). 

Q: From a sports medicine standpoint, do you think objective measures of gut health could realistically be something incorporated into a preparticipation exam? Or should it be more athlete specific during the season?  

Really good question! My guess is that it would be athlete specific simply because you’d have to have an athlete that was motivated and willing to make changes if you found dysbiosis. In my experience with athletes, if they don’t have a good reason to change their dietary habits (e.g., they feel bad), they won’t.       

Q: Do you have any information as to how bariatric surgery would affect the microbiome?  

It seems to have a large impact. Here is a study that outlines some of the effects: 

Ulker İ, Yildiran H. The effects of bariatric surgery on gut microbiota in patients with obesity: a review of the literature. Biosci Microbiota Food Health. 2019;38(1):3-9. doi: 10.12938/bmfh.18-018. 

Q: I know whole foods are best, but what do all of the additives and preservatives in various foods do to the gut?  

Zhou X, Qiao K, Wu H, Zhang Y. The impact of food additives on the abundance and composition of gut microbiota. Molecules. 2023;28(2):631. doi: 10.3390/molecules28020631.