Most Americans get less than half the recommended minimum daily fiber intake, which is problematic as the benefits of fiber go way beyond bowel regularity.

“Hippocrates, the father of western medicine, believed that all disease begins in the gut.” Of course, he also thought women were hysterical because of their “wandering uterus.” So much for ancient medical wisdom.

Even though a condition like constipation can have a “major impact…on physical, mental and social well-being,” it’s “often overlooked in health care.” This may be because poop-talk is “taboo,” but constipation can have “a severe influence on…everyday living,” both psychologically and physically. Constipation can literally hurt, causing “abdominal discomfort and pain, straining, hard stool, infrequent bowel movements, bloating and nausea.”

No wonder “laxatives are among the most commonly used drugs…Most are quite safe when used judiciously, intermittently,” but because people use them so frequently, laxatives end up being one of the most common causes of adverse drug reactions. Perhaps treatment should instead address the underlying problem that causes constipation, such as lack of dietary fiber. You probably don’t need a meta-analysis to demonstrate that “dietary fiber can obviously increase stool frequency in patients with constipation.” I discuss this in my video Friday Favorites: Is Fiber an Effective Anti-Inflammatory?.

“Populations in most Western countries must be considered on world standards to be almost universally constipated.” In the Western world, constipation is an epidemic among the elderly, but among those centering their diets around fiber-rich foods, it’s simply not a problem.

Where is fiber found? As you can see at 1:37 in my video, a patient summary in the Journal of the American Medical Association sums it up with an illustration of whole, unrefined plant foods. For those of us who may be smug about our hearty intake of fruits and vegetables, we need to realize that “fruits and leafy vegetables are the poorest source of plant fiber.” Why? Because they’re 90 percent water. Root vegetables have more fiber, but the real superstars include legumes, such as beans, split peas, chickpeas, and lentils, and we can’t forget whole grains. What about fruits? Gram for gram, fiber from fruits does not seem to have the same effect. It may take 25 grams of fruit fiber to double stool output, something just 10 grams of whole-grain fiber or vegetable fiber can do, as you can see in the graph below and at 2:08 in my video.

And that’s not all fiber can do. If you eat some whole-grain barley for supper, your good gut bacteria are having it for breakfast the next morning. This releases butyrate into our bloodstream, a compound that seems to “exert broad anti-inflammatory activities.” This could help explain why researchers found that “significant decreases in the prevalence of inflammation were associated with increasing dietary fiber intakes for all group.” As you can see at 2:44 in my video, the group with the highest fiber intake in the study had decreased inflammation—and that was with getting just the minimum recommended daily intake of fiber. So, if you have knee pain, for instance, should you eat more fiber-rich foods?

“Dietary Fiber Intake in Relation to Knee Pain Trajectory” is a study that followed thousands of patients. Researchers found that a high intake of dietary fiber, which is to say just the minimum recommended intake, was “associated with a lower risk of developing moderate or severe knee pain over time.” What’s more, two Framingham studies found that higher fiber intake was related to a lower risk of having symptomatic osteoarthritis in the first place.

Don’t a variety of diseases have an inflammatory component, though? How about “fiber consumption and all-cause, cardiovascular, and cancer mortalities”? Researchers found that, compared with those who consumed the least amount of fiber, those who consumed the most had 23 percent less cardiovascular disease mortality, a 17 percent lower risk of dying from cancer, and 23 percent lower mortality from all causes put together. “Unfortunately, most persons in the United States consume less than half of the recommended intake of dietary fiber daily.”

Researchers suggest all sorts of potential mechanisms for which fiber could be life-saving, such as improving cholesterol, immune function, and blood sugar control, but it may also have more of a direct cause. If you ask people to bear down as if they’re straining on stool, they can experience a rapid increase in intracranial pressure—that is, pressure inside your skull. And, if you look at trigger factors for the rupture of intracranial aneurysms and ask hundreds of people who had strokes or bleeds within their brains, one of the biggest trigger factors noted was “straining for defecation,” multiplying your risk by seven-fold.

This is one of the reasons legumes and whole grains are emphasized in my Daily Dozen checklist, which compiles all of the healthiest of healthy foods to ideally fit into your daily routine. It’s available (for free, of course!) as an app (Dr. Greger’s Daily Dozen) on [iPhone] and [Android], and you can learn all about it in my video Dr. Greger’s Daily Dozen Checklist.

If you buy processed grain products, how do you know they contain enough fiber? Check out The Five-to-One Fiber Rule.