What do we need to know about fiber? Dietary fiber consists of the non-digestible carbohydrates, mostly from components of plants. The human body does not make the types of enzymes needed to break the bonds in these fibers, so they pass through the body relatively intact. There are two types of fiber—soluble and insoluble. Soluble fiber attracts water as you digest your food, and turns into a type of gel. You can get soluble fiber in oat bran, nuts, seeds, and beans (to name a few). Insoluble fiber is found in whole grains and green leafy vegetables. You need both types of this fiber for optimal health.
Fiber Nourishes Your Gut Your gastrointestinal tract is home to trillions of beneficial microbes, called the gut microbiome, that live in a symbiotic relationship with you. This means that you benefit them and they benefit you. Just like you, these microbes need to eat to live and grow, so they obtain nourishment from the undigested part of the food, (fiber), that is passing through your intestines by fermenting it. Fiber that promotes the growth of the intestinal microbiome are called prebiotic fibers, and that not all fibers are considered prebiotic. A healthy gut microbiome can protect you against disease-causing bacteria because the good bacteria competes for space in the intestines, blocking the bad guys from taking hold. It can also help you absorb otherwise non-absorbable nutrients like certain antioxidant polyphenols, and produce vital micronutrients (like vitamin K5). Fiber Keeps You Feeling Full Longer Because fiber is so difficult for your body to break down, it stays in your gastrointestinal tract longer compared to simple carbohydrates like table sugar. Having food in your system helps you feel full for longer. This is the reason some studies show high-fiber diets help you eat less, which can impact weight management. Fiber Supports Healthy Cholesterol Levels Eating a diet high in fiber is associated with reduction of risk for cardiovascular disease, mostly because it helps to reduce “bad” cholesterol, low-density lipoprotein (LDL). Fiber (soluble fiber in particular) can support the reduction of “bad” LDL cholesterol without negatively impacting “good” high-density lipoprotein (HDL) cholesterol. Soluble fiber can be found in foods like oats, barley, lentils, some fruits and vegetables, and psyllium fiber supplements. Think of soluble fiber like a sponge, and dietary fat and cholesterol-carrying bile acids as liquid that you want to soak up and get rid of. The fiber soaks up particles the fat and bile acids from the intestines and holds on to them until they are excreted (in poop). The fiber not only helps to rid the body of dietary fat that can contribute to the cholesterol circulating in your blood, but it also helps to reduce your body’s production of cholesterol. Bile acids are particles involved in your body’s production of cholesterol, so ridding the body of some bile acids with fiber can reduce the amount of cholesterol produced by your body. Fiber Supports Healthy Blood-Sugar Levels Consuming a meal that’s mostly sugar or simple carbohydrates causes a wave of sugar into your bloodstream. High-fiber meals, however, help slow the emptying of the stomach, resulting in a trickle of sugar into the bloodstream. A slower release of sugar into the blood helps maintain a constant energy stream, rather than energy peaks and lulls. So, eat whole grains, legumes, fruits, and veggies as your carbohydrate sources to support healthy blood glucose levels. Fiber Makes You Go As in “go” we mean to the bathroom! Pooping is a fact of life, but when it’s difficult to go, it’s really not fun. Fiber helps you poop through several mechanisms that increase the weight of the stool, making it easier to pass. Insoluble fiber is the kind of fiber that does not absorb water (wheat bran, vegetables, or flax seeds). It adds physical bulk to the stool, making the stool larger.