Health Benefits of a High-Fiber Diet

Fiber has no sex appeal. The admonition to eat more "roughage" is as old as the hills. Heard it a million times. Been there, done that.

The problem is, most people aren’t doing it. In fact, though optimal health requires about 30 grams of fiber per day, Americans average only about 15 grams—half the recommended daily amount. 

Most people know that adequate fiber intake ensures regularity and protects against diseases of the digestive tract, from constipation to hemorrhoids to cancer. But are you aware that fiber and heart health are closely related, as are fiber and type 2 diabetes prevention? A 2019 meta-analysis published in The Lancet involving 243 studies and 4,635 individuals concluded that a robust intake of fiber from vegetables, fruit, legumes, and whole grains was associated with a 15–30 percent reduced incidence of heart disease, stroke, diabetes, colorectal cancer, and death. 

Your daily fiber intake also influences your weight and a wide range of other health concerns. Let's take a closer look at all these benefits of fiber.

Fiber and Heart Health

Want to dramatically decrease your risk of cardiovascular disease? Fiber is key. A  meta-analysis of more than 20 studies spanning almost 25 years of research reveals that every 7 grams of additional dietary fiber consumed per day confers a 9 percent reduction in cardiovascular disease.

Fiber also lowers cholesterol. Soluble fiber reduces cholesterol by binding to bile acids (much like cholesterol-lowering drugs called bile-sequestering agents) and causing them to be excreted. With fewer bile acids available in the intestine, less cholesterol is absorbed.

In addition, fiber slows the manufacture of cholesterol in the liver. This is important since a mere one-point reduction in cholesterol levels decreases the risk of heart disease by 2 percent. Adding just 5 to 10 grams of fiber per day can lower cholesterol by about 5 points, resulting in a 10 percent reduction in the risk of heart disease.

Fiber and Weight Loss

The benefits of fiber for weight loss are unmatched. Simply put, if you want to achieve and maintain your ideal weight, one of the most important things you can do is to increase your intake of fiber-rich foods.

First, fiber-rich foods take longer to eat than foods without fiber—you can’t chow down on apples and broccoli the way you can on chocolate and ice cream. This allows time for the signal of fullness to reach your brain, enabling you to stop eating before you’ve overstuffed yourself.

That feeling of satiety stays with you longer, too, because fiber slows the rate at which food leaves your stomach. Studies have shown that volunteers fed a high-fiber breakfast eat less at lunch than those who eat a breakfast that contains the same number of calories with no fiber.

Second, fiber prevents the roller coaster ride of dramatic spikes and just-as-sudden drops in blood sugar levels that leave you feeling tired and hungry. A fiber-rich lunch can help you resist that mid-afternoon candy bar. And if you grab an apple instead, chances are you’ll eat less at dinner, too.

Fiber and Type 2 Diabetes

The benefits of fiber for diabetes prevention are well-proven. Fiber protects against diabetes by increasing insulin sensitivity and helping with appetite control. In a large study that followed more than 160,000 women, those who consumed the most fiber-rich foods experienced a significant decrease in diabetes risk compared to women with the lowest intake. 

And if you already have diabetes, a high-fiber diet is one of the most powerful tools for controlling blood sugar. In patients with type 2 diabetes—and those with insulin resistance who are on their way to developing diabetes—blood sugar remains abnormally elevated, especially after eating. This prompts the release of increasing quantities of insulin from the pancreas, resulting in high levels of insulin in the bloodstream as well.

The conventional approach to this problem is to prescribe blood sugar-lowering drugs. But nature offers a much simpler and safer solution in the form of fiber-rich plant foods. Fiber slows absorption in the gastrointestinal tract, promoting a gradual rise in blood sugar levels, followed by a gradual release in insulin. It also improves the body’s sensitivity to insulin, combating insulin resistance and helping insulin to do its job of ushering glucose into the cells.

In one trial that compared a diet containing 24 or 50 grams of fiber daily, blood glucose levels were slashed by 10 percent with the high-fiber diet. This is remarkable because the drop was equal to that achieved by taking oral diabetes drugs! As an added bonus, the high-fiber diet boasted significant reductions in total cholesterol, LDL cholesterol, and triglycerides—something diabetes drugs could never do.

Fiber and Osteoarthritis

There's another little-known boon of this versatile macronutrient: It may also reduce risk and progression of osteoarthritis.

An observational study involving more than 6,000 participants spanning several years revealed that people who consumed the highest amounts of dietary fiber were much less likely to develop osteoarthritis of the knee—even after controlling for age, weight, activity level, smoking, and other common risk factors. Furthermore, among those who had arthritis, high fiber intake was associated with less knee pain, stiffness, and worsening of symptoms.

Add More Fiber

In order to realize the many benefits of fiber, you’ll need to add a variety of fiber-rich foods to your daily diet. Aim for a total of 30 grams each day. If you’re still coming up short, consider supplemental fiber sources, such as glucomannan, psyllium, or ground flaxseed. One tip: Buy whole flaxseeds and grind them yourself using an inexpensive coffee grinder. Cracking them open releases all their omega-3 oils, lignans, and other beneficial compounds. Pre-ground seeds can become oxidized and rancid, so grind them just prior to use to ensure freshness.

Below is a sampling of some other fiber-rich foods you can (and should) add to your diet.