Fiber and Your Microbiome

If you’re like me, you have heard a lot in the past couple years about the microflora inside our gut, and how critical it is to overall health.  We’ve been told to eat yogurt, eat fermented foods, take a daily probiotic, all in the name of giving power to the good bacteria inside us that helps us to digest our food and source the nutrients inside of what we eat.

And most of us know that fiber makes us feel full, but is feeling full the only thing fiber does for us?  I’ve read that fiber scrubs your intestines clean as it makes its way through you, but a recent study found that fiber’s benefits are more than just mechanical.  Fiber actually feeds the bacteria in our gut, which keeps our digestive system in good working order.

As it turns out, fiber is needed to give life to the bacteria inside us. What we once thought of as nothing more than gut-scrubbing filler is actually fuel for the bacteria.  Fiber, what we cannot digest from a plant, is actually digested by those bacteria, and is critical to them.  We can’t break down the fiber and use it as fuel, but the bacteria in our gut can.

The study looked at mice on a low fiber diet, and found that the population of the bacteria in the mouse’s gut shrank dramatically without enough fiber to sustain it.  More menacing was the fact that the mice on the low fiber diet actually experienced a shrinking of their intestinal wall, and a thinner mucus layer.  This meant the gut bacteria was much closer to the wall of the intestines, and to the rest of the body, which triggered an immune reaction.

Imagine your intestines as a pipe inside your home, and the bacteria is water traveling along inside of the pipe.  Everything is fine so long as the water is contained where it needs to be, inside the pipe.  If the water starts to leak out of the pipe due to thin walls, your home is in trouble.  Similarly, the body needs the bacteria in our gut to function, but the bacteria needs to stay safely in the intestines, and not travel outside and into the rest of the body.

With the dramatic rise of autoimmune diagnoses such as Hashimoto’s disease, lupus, or rheumatoid arthritis, the results of the fiber study make me to question whether our current epidemic of chronic inflammation gone wrong is tied to our low fiber diets.  The data certainly points in that direction, and there has been a lot of anecdotal evidence that rehabbing your diet can cure or drive into remission digestive disorders and even autoimmune diseases.

I loved this study, because was straightforward in terms of what you can do with the new discoveries: eat more fiber.  And not just one type of fiber, or from one source.  The study noted that some mice were given one type of fiber as a means of recovery, and other mice were given many types of fiber.  The mice eating one type of fiber improved from their inflammatory-inducing diet, but the mice who were given a wide variety of sources of fiber had the best recovery.  The researchers posited that the greater improvement from multiple sources of fiber was probably due to the fact that different bacteria require different sources of fuel.  Just as we need a varied diet, it looks like our gut bacteria does too.

This study adds to the growing literature that indicates the best diet for us is one full of variety, and full of plants.  To reduce inflammation and restore a healthy gut bacteria, ramp up your fiber intake from plant-based sources: vegetables, fruits, legumes, nuts, and whole grains.  It’s important to note that microbiome recovery is slower if you haven’t been eating as many plants, so as always, patience is the key.

I plan on putting this into action by trying to vary my foods more.  I can get into ruts quite easily, either through convenience or laziness, and this study shows how critical it is to get variety in your fiber sources, even if you have a healthy diet.  I tend to stay safe when it comes to cooking with new ingredients, but I see a shake up coming in my future.  Are you planning on making any changes?  Let me know!