long periods of physiological stress can change the composition of microorganisms in the gut

http://www.the-aps.org/mm/hp/Audiences/Public-Press/2017/27.html

Prolonged Military-Style Training Causes Changes to Intestinal Bacteria, Increases Inflammation
Physiological stress increases intestinal permeability in Norwegian soldiers

Bethesda, Md. (May 4, 2017)—A new study finds that long periods of physiological stress can change the composition of microorganisms residing in the intestines (intestinal microbiota), which could increase health risks in endurance athletes and military personnel. The study, published ahead of print in the American Journal of Physiology—Gastrointestinal and Liver Physiology, is the first to study the response of the intestinal microbiota during military training. The manuscript was chosen as an APSselectarticle for May.

Healthy intestines are semi-permeable and act as a defense both to let nutrients into the bloodstream and keep bacteria and other potentially harmful substances out. Physical stress can increase intestinal permeability (IP), which allows more materials out of the intestines and raises the risk of inflammation, illness and symptoms such as diarrhea.

A group of 73 Norwegian Army soldiers participated in a military-style cross country skiing training exercise. Over four days, the group skied approximately 31 miles (51 km) while carrying 99-pound (45 kg) packs. The researchers collected blood and stool samples before and after the training exercise. The soldiers took 24-hour urine tests before the exercise and on the third day of the trek, before which they drank a solution of water mixed with the artificial sweetener sucralose and mannitol, a sugar alcohol. The human body does not break down sucralose during digestion, but gets rid of the sweetener through urination. Levels of excreted sucralose are commonly used as a marker for IP.

The microbiota and the composition of substances produced during metabolism (metabolites) in the soldiers' blood and stool changed significantly by the end of the aggressive training period. Sucralose excretion rose considerably, indicating an increase in IP. Concentrations of several compounds that are products of bacterial metabolism of amino acids and fat decreased in the stool, and levels of more than half of the different compounds found in the volunteers’ blood changed during the military training session.

Changes in IP were associated with changes in inflammation, the composition of the intestinal microbiota before training and changes in several metabolites possibly derived from the microbiota. “[Previous] human studies have demonstrated that drastic changes in diet impact intestinal microbiota composition by altering the availability of metabolic substrates for intestinal microbes. Our findings contrast with those reports in demonstrating alterations in microbiota composition that most likely were not solely attributable to diet, and which were more pronounced than is commonly reported in human diet studies,” the researchers wrote.

Intestinal microbiota appear to be one influencing factor in the gut’s response to physical stress. “Our findings suggest that the intestinal microbiota may be one mediator of IP responses to severe physiologic stress, and that targeting the microbiota before stress exposure may be one strategy for maintaining IP,” the researchers wrote.

The article, “Changes in intestinal microbiota composition and metabolism coincide with increased intestinal permeability in young adults under prolonged physiologic stress,” is published ahead of print in the American Journal of Physiology—Gastrointestinal and Liver Physiology. It is highlighted as one of this month’s “best of the best” as part of the American Physiological Society’s APSselect program. Read all of this month’s selected research articles on the APSselect website.

 

I (and a lot of others) report coming down with me/cfs at a point in their life where they were very fit, and doing a lot of exercise.

You have to wonder whether screwed up gut bugs might make a person more susceptible?

 

I don't have the wherewithal at the moment to process this study thoroughly. However, several questions come to mind.

These soldiers were exposed to extreme physical stress that most people don't experience. Can this physcal stress even be comparable to a specific stressor such as a virus or other factors that started someone's me/cfs and/or the stress that goes with having this illness vs the "normal" stress of every day life? My uneducated guess is that they are all different. No I am not saying psychological stresses are the main reasons for getting ME. But this piqued my curiosity.

I also wonder if any tests were given after more than three days where the body would have more time to recover.

Apologies if these questions have been answered in the study. I'll try to read it tomorrow and if I'm repeating anything, will delete that information.

It's quite an interesting topic.

By the way, I often feel like I'm carrying around a ninety pound backpack. It's exhausting.

 

I'd buy that for a dollar.

Seems more and more studies point the finger at the gut microbiota these days... kinda like (one of) the last great uncharted territories of the body's health.

However, one must as usual beware of angles such as this... instead of getting drugs to treat, correct or even protect the flora and fauna of the gut, there is always a risk of being blamed instead and 'manning up' and avoiding stress and meditating til til you hover around the room will be the therapy of choice! Cos, ya know, it's our fault after all.

 

I can't help but chuckle.

Intestinal Permeability.

Sounds eerily similar to Leaky Gut Syndrome.

Yet another thing the "quacks" have talked about for decades ;-)

 

Interesting.

These people were tested and found to have changes but how did that affect their functioning after? Sounds like there needs to be long term follow up.

What I would also be interested in is when these studies are done attempts to understand why some people do not have the changes noted.

@TenuousGrip

You may want to have a look at Ian Lipkin's (Columbia University-Epidemiology) work on ME/cfs:

http://advances.sciencemag.org/content/1/1/e1400121


Washington Post article: https://www.washingtonpost.com/news...e-to-do-with-your-gut/?utm_term=.e4f82e9f6814

I'm not suggesting that the research discussed in this thread conclusively proves anything. I have no way of knowing this.

 

Fascinating, @Snowdrop . Thanks for those.

As usual, I was painfully aware of this line:

It almost seems as though ... a few hundred more of these ... and a few more generations ... and it'll be hard for physicians to keep calling us all whack-jobs ;-)