From heart health to trim waist lines to healthy bowel movements, fiber’s got you covered.
This is Part II in my three-part series on low-carb diets and fiber. As explored in my previous post, the paleo and ketogenic (“keto”) diets are powerful therapeutic tools. It’s all too easy, however, to forget to eat enough fiber while following a low carb plan. In this post we’ll dive deep into the fantastic world of fiber and explore what this nutrient can do for you. In the next post I’ll share some strategies and recipes for increasing your fiber intake without having to “cheat” on Dr. Atkins.
Why Fiber is Important
Fiber’s healing benefits are numerous. This plant-based nutrient has been shown to:
Reduce the risk of cardiovascular diseases like coronary heart disease (CHD) and stroke. It also lowers the levels of harmful cholesterol while enhancing the levels of HDL, or “good” cholesterol, and has even been shown to help lower blood pressure.
Stabilize blood glucose (aka “blood sugar”), fight insulin resistance, and thus lower the risk of diabetes and other related conditions.
Improve the frequency and consistency of bowel movements, thus reducing both diarrhea and constipation and generally supporting colon health. Fiber has also been shown to alleviate the symptoms of irritable bowel syndrome (IBS).
Balance hormone levels in the body, in part by increasing the production of sex hormone binding globulin (SHBG). This is key for managing diseases associated with hormone imbalances, such as polycystic ovary syndrome (PCOS).,
Control appetite and support a healthy weight: Fiber-rich foods tend to be more filling than foods low in fiber, enabling us to eat less at mealtimes and stay full for longer. This is why people on a low-carb diet tend to snack more between meals. Fiber-rich foods also deliver fewer calories per bite than, say, protein-rich foods do.
So! Fiber is clearly an important part of a healthy diet. But what is it, actually?
What is Fiber, Anyway?
Fiber is a plant-based nutrient that typically passes through the digestive tract intact without getting broken down into its component sugars.
The types of fiber are typically sub-categorized into insoluble and soluble fiber:
Insoluble fiber, which promotes healthy bowel movements by more or less retaining its form while absorbing water, thereby creating soft yet bulky stools. In the process insoluble fibers help decrease the type of bowel pressure that otherwise leads to diverticula (pouches). By speeding up “transit time” (the speed at which food travels down the intestines for elimination), furthermore, insoluble fiber decreases the body’s exposure to the toxic metabolites being carried out in the stool. Sources of insoluble fiber include wheat bran, whole-wheat flour, nuts, beans, cauliflower, green beans, and potatoes.
Lignans, a type of insoluble fiber found in seeds and legumes, have been shown to have not only antioxidant activity, but also noteworthy hormone-balancing effects – namely in reversing estrogen-dominant states. Lignans can thus help regulate the menses, balance the hormones, and in turn prevent certain types of cancer. The richest source of lignans is in flax seeds, which I prescribe (ground up in a coffee grinder) to just about every woman in my practice with hormonal imbalances. Whereas whole flax seeds provide insoluble fiber, the ground seeds contain both soluble and insoluble forms.
Soluble fiber dissolves in water to create a gel-like material that is fermented in the colon. It also slows down the rate of the stomach’s emptying, thereby helping us feel full for longer after we eat. Soluble fiber also helps delay the body’s absorption of glucose (sugar) from food, thus tempering the “spike and crash” some experience after meals and lowering the risk of type 2 diabetes. On its way down the digestive tract, soluble fiber binds to bile acids, thereby helping to lower harmful cholesterol levels. Sources of soluble fiber include oats and oat bran, peas, beans, apples (with their skins), barley, fruits, and berries.
Inulin is a type of soluble, fermentable fiber that withstands digestion by the upper digestive tract and supports the growth of beneficial bacterial. Whereas probiotic foods (like plain yogurt and sauerkraut) contain live organisms that (theoretically) populate in our guts upon consumption, inulin is a prebiotic – a substance that feeds the healthy bacteria already residing in our digestive tracts. A common type of inulin is fructo-oligosaccharide, or FOS, which is sometimes added to probiotic supplements. Because it has a slightly sweet flavor, is low in calories, and does not trigger a rise in blood sugar or insulin levels, FOS is commonly used to enhance the flavor of low-calorie/low fat foods. Dietary sources of inulin include artichokes, garlic, leeks, onions, chicory, and soy products, and grains such as barley, flax, oat, and wheat. (Note: inulin and FOS may aggravate some individuals with untreated small intestine bacterial overgrowth, or SIBO.)
Take the Fiber Challenge
Are you ready to take the fiber challenge? The fiber challenge consists of eating 30 to 50 grams of (gluten-free) fiber per day. The average American consumes 8 to 12 grams of fiber per day (including gluten), so chances are it’s time to up your fiber game.
How much is 30 to 50 grams? Explore this handy chart (PDF) of gluten free foods and how much fiber they contain, courtesy of Riley Wimminger, MScN at Bridgetown Nutrition.
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Chart of fiber-containing foods courtesy of Riley Wimminger at Bridgetown Nutrition.
Image courtesy of artur-rutkowski for Unsplash.