By now you’ve probably heard that fiber really “gets things moving”. Sure, that’s a big part of its magic, but its benefits extend FAR beyond digestion. Fiber supports heart health, helps regulate blood sugar, aids in weight management, and nourishes your gut. In short, it’s one of the most powerful, and accessible, daily tools for supporting your overall well-being.
Improves digestion
There are two kinds of fiber: soluble and insoluble. Most fiber-rich foods contain a mix of both, but they work in distinct ways. You can think of insoluble fiber as the bulking agent, helping waste move through your colon quicker and more efficiently. Conversely, soluble fiber acts more like a sponge, dissolving in water to form a gel-like substance that softens your stool and slows its transit through your digestive tract. Soluble fiber also happens to be an incredible source of food for your gut bugs – more on that later. For now, just know this: if you frequently get backed up, boost your intake of insoluble fiber (along with plenty of water!); if you’re more on the loose-stool side of the spectrum, opt for soluble fiber.
Supports heart health
Every time you eat a meal, your liver secretes a digestive fluid called bile into your small intestine where it helps to break down fats. Bile is made in part from cholesterol, and under normal circumstances, your body recycles most of it in order to save energy and avoid starting from scratch. But here’s where fiber comes in. Soluble fiber (that gel-like substance we talked about earlier) binds with bile in your digestive tract and carries it out of your body with your poop. This forces your liver to create more bile by pulling cholesterol from your bloodstream, effectively lowing your circulating cholesterol levels (especially LDL, the “bad” cholesterol. Research shows that adding just 10 grams of soluble fiber can significantly reduce both LDL and total cholesterol levels (7). On top of that, soluble fiber slows the absorption of dietary fats and the digestion of carbohydrates – both of which support cardiovascular health.
Feeds your microbiome
Unlike other nutrients, fiber passes through your digestive system largely undigested until it reaches your colon. There, beneficial gut microbes ferment it, producing short-chain fatty acids (SCFAs) like butyrate, acetate, and propionate. These metabolites are hugely valuable as they fuel the cells that line your intestines (called enterocytes), support tight junction integrity (which helps prevent leaky gut), and modulate your immune system.
Butyrate, in particular, is crucial for maintaining a healthy gut barrier. It upregulates genes that produce tight junction proteins, essentially reinforcing the seal between your intestinal cells. This helps keep inflammatory compounds and pathogens out of your bloodstream, which can wreak havoc on your immune system.
SCFAs also help shape your gut ecosystem by feeding beneficial bacteria like Faecalibacterium prausnitzii and Roseburia, while creating a more acidic environment that inhibits harmful microbes like Clostridium difficile. Clinical trials suggest that high-fiber diets that enhance SCFA production can reduce dysbiosis by increasing populations of Bacteroidetes – an important commensal gut bug (2).
Regulates blood sugar levels
Because soluble fiber slows overall digestion, it also slows the breakdown and absorption of carbohydrates. This means that glucose enters your bloodstream more gradually, leading to a smaller blood sugar spike post-meal. Better yet, SCFAs in your gut stimulate the release of gut hormones like GLP-1 and peptide YY, which enhance insulin secretion and reduce your appetite (4). SCFAs also reduce glucose production in your liver, contributing to a lower fasting blood sugar level. This is why taking a fiber supplement, like partially hydrolyzed guar gum (PHGG) or psyllium husk can be especially helpful for people with Type 2 Diabetes, as it allows them to process high-carb meals without adverse blood sugar effects (1, 3). Clinical trials show that viscous/soluble fibers like PHGG and beta glucan can significantly reduce hemoglobin A1c (HbA1c) levels – a measure of your average blood sugar over a 3 month period and the gold standard for pre-diabetes and diabetes diagnoses (5).
Aids in weight management
Ever notice how a big, beautiful salad full of beans, veggies, seeds, whole grains (like quinoa) and nuts keeps you full way longer than a more calorie-dense meal like a sandwich? That’s all thanks to fiber. Here’s the science behind it. Insoluble fiber (think: roughage) is bulky and takes up a lot of space, so it stretches your stomach and triggers stretch receptors that send fullness signals to your brain. Meanwhile, soluble fiber slows down gastric emptying which also keeps you feeling more satiated for longer. It also reduces hunger hormones, like ghrelin, and increases satiety hormones, like GLP-1 (6).
Vegetables, legumes and other high fiber foods are typically low in calories, meaning you can eat a much larger volume of them without hitting the caloric intake you would with more energy-dense foods. And because soluble fiber can bind to some dietary fat and sugar in your gut, it reduces their absorption and blunts their impact on your blood sugar. This is why sometimes nutritionists say to “eat your fruits and juice your vegetables”. Without fiber to act as a buffer to slow things down, the natural sugars in fruit juice get absorbed extremely quickly into your bloodstream, causing blood sugar and insulin spikes. Over time, this can cause metabolic dysfunction and bigger issues like insulin resistance, hyperglycemia and even diabetes.
