This holiday, don't forget your gut microbiome.
Gone are days when we saw the plethora of microorganisms that colonize our bodies as mere hitchhikers.
Today, we appreciate that our gut microbiota plays a crucial role in our health. We need to keep our tiny partners-in-crime happy; if we don't, things can go sour rather quickly.
Dr. Sven Pettersson — a professor of metabolic disorders at the Lee Kong Chian School of Medicine in the Nanyang Technological University in Singapore — and colleagues explain in a review article in the journal Cell, out earlier this month, that our gut microbiome naturally changes throughout our lifetime.
What starts out as a simple collection of a handful of bacteria matures into a complex microbial ecosystem, heavily influenced by factors including our diet, lifestyle, hormones, and immune system.
Imbalances in our gut flora are linked to a steady rise in conditions such as food allergy, eczema, asthma, autism spectrum disorders, chronic fatigue syndrome, irritable bowel syndrome, and cancer.
So, as the year draws to a close and we sit back and take stock over the holidays, let's look at what can we do to look after our gut microbes, especially at a time marked by calorific excesses.
1. Don't forget your fiber
While we cannot digest fiber ourselves, microorganisms readily use it as a food source. If there isn't enough fiber in our diet, microbes start to gobble up the mucus barrier in the gut as an alternative food source. This allows microorganisms to cross the now "leaky" gut barrier, causing havoc.
A leaky gut can put us at risk of colitis, inflammation, and metabolic syndrome, among other conditions.
Writing in the journal Cell Host & Microbe, two research groups report what happens when we switch to a Western-style diet — which is low in fiber — even just for a short period of time.
Within just 3–7 days, mice fed a low-fiber diet showed signs of a leaky gut, drastic weight gain, high blood sugar, and insulin resistance. This was accompanied by widespread bacterial death in the gut, which tipped the balance in favor of some of the more unsavory bacterial species, such as Bacteroides and Actinobacteria.
"Diets that lack fiber," explains study co-author Gunnar C. Hansson, a professor in the Department of Medical Biochemistry at the University of Gothenburg in Sweden, "alter the bacterial composition and bacterial metabolism, which in turn causes defects to the inner mucus layer and allows bacteria to [encroach], something that triggers inflammation and ultimately metabolic disease."
Add fiber to reverse symptoms
Prof. Hansson and colleagues found that bacteria that degrade fiber, such as Bifidobacterium, were greatly reduced on the Western-style diet. But, they also showed that adding Bifidobacterium or inulin — a type of prebiotic plant fiber — to the mice's diet could improve gut health.
The second research group, which was led by Andrew Gewirtz — a professor at the Center for Inflammation, Immunity & Infection at Georgia State University in Atlanta — found that inulin supplementation can restore gut health and reduce the signs of metabolic syndrome to some extent.
However, before you rush off to stock up on inulin to counteract the excesses of your holiday diet, Prof. Gewirtz issues a warning.
"Simply enriching processed food with purified fibers might offer some health benefits, but we're not ready to recommend it until we understand more of the very complex interplay between food, bacteria, and host."
Prof. Andrew Gewirtz
Instead, you could opt for holiday foods that naturally pack a fiber punch instead. Check out these handy recommendations in the American Heart Association's (AHA) Holiday Healthy Eating Guide.
2. Treat your gut to some chocolate
Cocoa — which is the dry, non-fatty component of chocolate — contains a host of molecules that are increasingly making health news headlines. Rich in antioxidants and fiber, cocoa has been linked to a string of health benefits, from lowering cholesterol to benefiting fetal development during pregnancy.
When it comes to our gut health, cocoa consumption has been shown to reduce inflammation, potentially alleviating the symptoms of inflammatory bowel diseases (IBD) such as Crohn's and ulcerative colitis.
Earlier this year, we reported on research that showed that cocoa components can reduce bacteria in the Clostridium family, which are often found in the guts of those with IBD. When human study subjects drank high-cocoa chocolate milk over a period of 4 weeks, Lactobacillus and Bifidobacterium species shot up in numbers in their guts.
However, it is also worth remembering that not all chocolate is created equal. Unsweetened cocoa powder and dark chocolate with a high cocoa content are the closest you can get to the cocoa formulations used in scientific research.
So, why not pick out a nice piece or two of dark chocolate when the boxes of festive treats are making the rounds.
3. Work your holiday pounds
Earlier this month, Medical News Today reported on two studies that demonstrate the power of exercise: it can directly affect the diversity of your gut microbiome.
One of the studies looked at the effects of exercise in mice. One group was active, while the other was sedentary. The researchers transplanted fecal material from both groups into the colons of mice bred under germ-free conditions.
The results showed that the mice that had received fecal transplants from exercise mice had more bacteria in their colons that can metabolize fiber into molecules called short-chain fatty acids (SCFAs), which are beneficial to health. These mice also had lower levels of inflammation.
In humans, similar findings hold true. The second study revealed that just 6 weeks of exercise led to an increase in SCFA levels and SCFA-producing microbes in both lean and obese individuals.
However, while both experienced this increase, it was more pronounced in lean individuals.
Don't let that put you off, though, whatever your weight. Whether you are off for a brisk walk after a big family meal or dancing around the living room to silly Christmas songs, get moving to give your gut a head start.
4. Don't let the holiday stress get to you
Writing in the journal Scientific Reports, a research team from the Department of Microbiology and Molecular Biology at Brigham Young University in Provo, UT, found that when female mice were exposed to chronic unpredictable stress, their gut microbiome changed drastically.
The bacterial diversity shifted in favor of members of the Lachnospiraceae, Ruminococcaceae, and Peptococcaceae families. In fact, this profile resembled the microbiome of mice fed a high-fat diet. So, even with the best diet in the world, stress may still tip the balance in your gut microbiome.
While the researchers observed these particular changes only in female mice, holiday stress is a ubiquitous phenomenon that both sexes are known to experience.
But fear not: we have put together this handy guide on "How to reduce Christmas stress" for practical tips to manage over the holidays.
Your gut health in 2018
With this collection of tips, your gut microbes will — hopefully — thank you for getting them safely through the holidays and off to a good start in the new year.
No doubt 2018 will continue to see new research into how our microbiome shapes our health, and, importantly, what we can do to keep our guts in tip-top shape.