After my most recent post "Nourishing the Gut" a reader wrote in with the following question: so I have read some where that there are certain kinds of fiber that are more beneficial to gut guys. What's the deal with that?
Let's take some time to talk more about fiber. Fiber is essential for optimal digestive health. It is recommended that we eat 25-30 grams of fiber per day however, the average American eats about 15 grams of fiber per day. That is an "F" in my book. And not F for Fiber, F for FAIL.
Fiber represents a group of carbohydrates or carbohydrate-containing compounds. We tend to classify fiber based on whether it is soluble in water. That is just a fancy way of saying, it absorbs water. Some fibers do, others done. Unlike most carbohydrates, fiber is not digested or absorbed in the small intestine. What does that mean? It means it makes it's way to your large intestine (also known as your colon) fairly intact. Why? Humans lack the digestive enzymes to properly break down fiber. Don't worry, we still need it. This just means, you aren't a cow, who can turn grass or hay into energy.
Soluble vs. Insoluble
So soluble fiber and insoluble are both very important, they just each provide their own benefits. Soluble is the kind of fiber that decreases blood cholesterol levels, it provides bulk to stool - which is a good thing. This type of fiber is in apples, the pulp in oranges, foods like oats, and dry beans.
Insoluble fiber remains VERY unchanged as it passes through your small intestine. It helps move contents through your guts. This type of fiber is what you find in the peels of fruits, like that apple from above, it's skin or peel is insoluble fiber. Insoluble fiber is in seeds, it is more often the type of fiber in vegetables and whole grain products, corn and brown rice.
Fiber is a "prebiotic" food. That just means, it is a food source for the biome of bacteria in your gut.
Okay, but the question above had to do with our gut guys, the friendly bacteria in our gut that we would like to support. The long and the short of it is this: the fibers that are more fermentable are the fibers these guys feast on. The few that are proven to be very preferential for the microbiome include: inulin (which occurs naturally in leeks, asparagus, chicory, garlic, onions, wheat, oats, and soybeans), oligofructose (bananas, onions, Jerusalem artichoke), galactooligosaccharides (which is found most beneficially in human breast milk, but can be found in dairy products and is often packaged as a prebiotic food right in yogurt).
Here are a few sources of great foods with a mixture of two of the above fiber types that our "gut guys" love:
This is just a sampling. To keep things simple. It is important that we eat a wide variety of plant based foods to ensure we are giving our bodies adequate sources of fiber. When shopping for any type of bread, look at the fiber, if per serving it is less than 5 grams of fiber, don't waste your money. Eat 2-3 servings of fresh fruit per day, and eat 4-7 servings of vegetables (cooked and raw). Choose brown rice over white, choose whole grain pasta over white, choose cruciferous vegetables like broccoli, brussels sprouts, cabbage, cauliflower, collard greens, kale, turnips, and bok choy. Eating a wide variety of plant based fruits and vegetables will make sure you are eating the types of fiber the microbiome loves.
WHY DOES THIS MATTER?
We carry around 3 pounds of gut bacteria in our body at any given time. That is as much as your brain weighs. You have GALT cells (gut associated lymphoid tissue) in the lining of your intestines that represents the largest mass of lymphoid tissue in the body, approximately 25% of the intestinal mucosa consists of lymph tissue. The immune responses that start in the gut have GREAT potential to affect all the areas of our body, and inflammation levels. These GALT cells feed primarily on short chained fatty acids, which is what you microbiome is turning the fiber you eat into.
Fiber + Gut Bugs = Short Chain Fatty Acids
Short Chain Fatty Acids + GALT cells = Healthy Immune Response
No wonder we in America are suffering from so many chronic, inflammatory diseases, and autoimmune diseases when we are getting an "F" when it comes to eating enough fiber.
I will mention if anyone reading this has considered a low FODMAP diet due to IBD, consult your healthcare provider before increasing the fiber in your diet.
Caitlin Johnson is a dietitian, wife, lover of ice cream, chef wannabe, California-girl, Christian, liver eating, "food-avore."
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