You may roll your eyes when you hear the old motto "you are what you eat," but it turns out there is actually more truth embedded in the phrase than you think....especially when we bring our gut microbiome into the picture.
Though we may not hear or see them, trillions of microorganisms--bacteria, fungi, yeasts, viruses--are residing within us. At this very moment, they are on the surface of our fingers, hands, mouth, ears, tongue, and gastrointestinal tract. While it is probably hard for you to wrap your head around this idea, these microbes play a MAJOR role in supporting our immune and digestive health. They help us to extract energy from the non-digestible components of food (for example, fiber), synthesize certain vitamins (like vitamin K), and ward off the harmful microorganisms that try to invade our mucosa--just to name a few!
United at Birth
So, when do these microorganisms invade our bodies without us knowing.. and HOW?!
Believe it or not, we are colonized with our mother's vaginal microbiome as soon as we pass through her birth canal. For those of us who are born via Cesarean section, most of the microbes we obtain are from the surface of our mother's skin. From there, these microorganisms pretty much take claim over our entire bodies; they form tiny communities within us, carry out numerous, versatile tasks, and evolve as we grow and develop.
A Two Way Street
What makes our human microbiome so unique is that no two people have the same one. Research shows that the actual composition differs from person to person and is largely dependent on our individual lifestyle, dietary behaviors, antibiotic use, and disease state. There is a growing body of evidence that shows the flip side is also true; the species of bacteria we "cultivate" in turn shape our body composition, the way in which we utilize nutrients, and our overall health.
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Take this as an example:
Numerous studies over the past several decades have reported differences in the gut bacterial profile between persons who are overweight and those who are lean. Their main finding: overweight individuals with a high-fat, high-sugar diet tend to have a greater concentration of Firmicutes bacteria. This particular species of bacteria is extremely efficient at extracting energy from food, and thereby likely to contribute to weight gain.
Microbiome research, however, is still in its infancy. Scientists are now looking into the activity of microbes (i.e. the proteins and metabolites they produce) to obtain a better understanding of their role in preventing and treating disease.
Eat Your Way to Gut Health
While there is so much that is yet to be discovered, we do know a thing or two about the foods that influence our gut microbiome. Eating dietary fiber, for instance, is associated with a highly diverse and "good"microbiome. Fiber is the part of plant-based foods (whole grains, fruits, vegetables, nuts, and beans) that the human body cannot break down. It is best known for its ability to pass through the body undigested, facilitate bowel movements, and flush cholesterol and harmful substances out of our bodies.
Fiber is also an important component of prebiotics. Prebiotics are non-digestible, plant-based food ingredients that are broken down for energy in our large bowel. Here, they act as fertilizer for our gut by selectively nourishing the "good" bacteria that already exists there. Dietary fibers that fit the criteria for prebiotics include: inulin, trans-galactooligosaccharides (say that 10 times fast!), resistant starch, pectin, beta-glucans, fructooligosaccarides, arabinose, wheat dextrin, and lactulose.
Another group of "functional" foods that often go hand-in-hand with prebiotics are probiotics. Probiotics, primarily found in dairy products and fermented foods, are defined by experts as live microorganisms that confer health benefits on the host (aka us). Though most of these health benefits are in the area of bowel regularity, recent research suggests that probiotics also play a role in gut immunity. For example, certain probiotic strains, particularly Bifidobacteria and Lactobacilli, have been found to modulate the immune response of intestinal mucosal cells. These species are capable of increasing the number of beneficial bacteria in our gut and inhibiting the growth of harmful species, potentially reducing the risk of certain intestinal viruses.
A variety of pre- and probiotic supplements are also available on the market; however, it is important to keep in mind that these supplements do not always guarantee the same diverse live cultures as natural food sources do. With that said, be a smart shopper!
PROBIOTIC-RICH FOODS
- Greek Yogurt
- Kefir (fermented milk drink)
- Aged cheeses (i.e. parmesan, cheddar, gouda)
- Sauerkraut (lacto-fermented cabbage)
- Kimchi (spicy Korean fermented side dish)
- Natto (fermented soybean)
PREBIOTIC-RICH FOODS
- Whole grains (fiber, wheat dextrin)
- Garlic, Jerusalem artichokes (inulin)
- Legumes (fiber)
- Bananas (fructooligosaccharides)
- Nuts and seeds (arabinose)
- Oats and barley (beta-glucans)
The Bottom Line
Although research is ongoing, the evidence that supports the consumption of dietary fiber, prebiotics, and probiotics to support our gut function and overall well-being is quite convincing!
References
Chakraborti, C. K. (2015). New-found link between microbiota and obesity. World Journal of Gastrointestinal Pathophysiology, 6(4), 110–119. http://doi.org/10.4291/wjgp.v6.i4.110
L.D., K. Z. (2017). Probiotics and prebiotics: What you should know. Retrieved from https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/probiotics/faq-20058065
Round, J. L., & Mazmanian, S. K. (2009). The gut microbiome shapes intestinal immune responses during health and disease. Nature Reviews. Immunology, 9(5), 313–323. http://doi.org/10.1038/nri2515
