“You need more fiber in your diet”. I’ve heard the phrase so many times it’s basically lost all meaning for me. My mom and mothers all over the world have been uttering these words for decades. When you ask them why, the general response is: “It’s good for you.”
Why is it good for you? We know a diet with enough fiber (25g/day for women and 38g/day for men) is associated with maintaining a healthy weight, lowering the risk of diabetes, lowers the risk of heart disease, lowers cholesterol, helps control blood sugar levels, and normalizes bowel movements.
But, what is it about a diet high in fiber-rich foods that provides so many benefits?
Some recent studies have begun to provide some answers. This article is going to touch on that research. It will tell you everything you need to know about the bacteria in your gut and how fiber influences those bacteria and the rest of the body.
If you’re looking for some more basic information about dietary fiber (what it is, what foods to get it from, etc.), click here.. It’ll take you to an article that acts as a good primer for what we’re going to discuss today.
Your intestinal bacteria and you
When we think of bacteria, we often think infection and disease – these little microbes have a bit of a bad rap. They’re not all bad. In fact, many, if not most, are quite critical to your health and wellbeing.
Living inside you in your intestine right now are approximately 300 to 500 different kinds of bacteria. And they’re not causing any problems, they’re living there to help you out.
How important is your microbiota? Well, its particular makeup can affect everything from your metabolism to your mood to your immune system. You’re basically at the mercy of microbes living right beside your poop – that’s a weird thought isn’t it?
Each person’s microbiota is as unique to them as their fingerprints. Your particular microbiota makeup is partially determined at birth (you acquire some of your mother’s as you slide through the birth canal into existence) and the rest is determined by your diet and lifestyle.
Dietary effects on intestinal bacteria is where fiber comes in.
Dietary fiber and your intestinal bacteria
Researchers are now learning how dietary fiber impacts intestinal bacteria.
Dietary fiber is unique because we can’t digest it. Digestion of whatever we eat (protein, fat, and carbohydrates) depends on biological machines called enzymes to break down the molecules and turn them into something we can use as energy.
Humans lack the enzymes required to break down fiber. So, it passes through our digestive system relatively intact until it gets to the intestine. Here’s where our little microscopic buddies spring into action and do us a real solid.
Many types of intestinal bacteria do have the enzymes needed to break down fiber. These bacteria lie on a layer of mucus, which separates them from the cells that make up the intestinal wall.
Intestinal bacteria break down the fiber passing through the digestive system and cast off the byproduct into the intestine.
Interestingly, these byproducts are now something the intestinal cells do have the enzymes to break down and use as energy. Intestinal cells take advantage and use these byproducts as a food source.
Alongside the use of bacterial byproducts as a source of energy, intestinal cells rely on bacteria in other ways.
Chemical signals, for example.
Signals from bacteria cause intestinal cells to produce mucus. And this mucus layer is really important; the mucus layer separates intestinal cells from bacteria. This, we’ve now learned, has some major effects on health.
Dr. Andrew Gerwirtz and his team at Georgia State University tested the effect of a low-fiber diet on the microbiota of mice.
They found that decreasing fiber content in the diet changed the bacterial species making up the microbiota. They also observed profound changes in the mucus layer: it got much thinner.
As a result, bacteria were much closer to the intestinal cells and were able to trigger an immune reaction.
Immune reactions are good in small doses. They are a critical part of beating infection, preventing disease, and healing.
Too much of a good thing, however, can cause some real problems; it can interfere with how the body uses calories in food, storing most of it as fat, for example.
This is what Gerwirtz and his colleagues observed in the mice left on a low-fiber diet for a few weeks. They began to put on fat and develop higher blood sugar levels.
Inflammation such as the kind observed in the intestine of the mice may not be limited to that area. The byproducts of fiber digestion from bacteria that intestinal cells use as food can also get into the blood stream and interact with other organs. There they act as signals to quiet down the immune system.
Who knew fiber and bacteria could have such a huge effect on you.
Dietary fiber is an integral part of a healthy diet because it helps prevent disease and mortality, it keeps you regular, and it helps manage weight.
We now know better than ever before how it does this: by keeping the bacteria in your intestine fed and happy.
In light of this new research, make sure you’re getting enough fiber in your diet. That means 25 grams per day for women and 38 grams per day for men.
If you can’t get this much from a diet rich in fruits, vegetables, and whole grains, consider a supplement. Please contact me about some options, I’d love to help you out.
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