You probably already know that fiber is an important element of a well-balanced diet. Packed into foods like fruits, vegetables, and legumes, this indigestible carb has long been touted for promoting healthy digestion, supporting satiety and weight loss, and more. Recently, research has even identified its role in fighting inflammation.

However, despite its long list of benefits, most of us—yes, even the most health-minded people—don’t eat enough fiber. And, according to World Health Organization-funded research, this could have long-term health consequences much more serious than a little constipation.

The Research

Enter a new paper published in The Lancet that highlights exactly how our fiber intake affects our health in the long run. For the study, researchers reviewed and analyzed 40 year’s-worth of previous data—185 studies and 58 clinical trials, to be exact—to explore fiber’s ability to protect our health and predict risk of chronic diseases.

Related: 5 Things You Can Do Every Day To Fight Inflammation

While it’s not the first review to look at fiber and health, this review looked at the amount of fiber people ate and what type of foods that fiber came from. Whether foods were refined or whole, and their glycemic index (how much they affect blood sugar levels) were taken into account.

The goal: To determine exactly what fiber-filled foods—and how much fiber overall—to recommend for protecting against disease and death.

The review’s first major takeaway: People who ate higher-fiber diets saw a 15 to 30 percent lower risk for all-cause and cardiovascular-related mortality, incidence of coronary heart disease, stroke incidence and mortality, type 2 diabetes, and colorectal cancer compared to people who ate less than 15 grams of fiber per day.

In fact, for every eight-gram increase in dietary fiber eaten per day (about the amount in apple and two tablespoons of peanut butter), total mortality and incidence of coronary heart disease, type 2 diabetes, and colorectal cancer decreased by five to 27 percent. Talk about a return on your investment!

Related: What To Know If You Want To Cut Refined Carbs

The review reported a similar, though slightly weaker, effect in people who ate whole grains versus refined grains.

“The analyses presented […] provide compelling evidence that dietary fiber and whole grain are major determinants of numerous health outcomes and should form part of public health policy,” said Professor Gary Frost, Head of Nutrition Research at Imperial College London in the study press release.

So, What’s The Fiber Sweet Spot?

According to the Lancet paper, consuming between 25 and 29 grams of fiber per day generated the greatest health risk reduction.

While this falls in line with the Institute of Medicine’s recommendation that men and women eat 25 and 38 grams of fiber a day, respectively, it suggests the FDA’s general recommendation of 25 grams of fiber per day may be more of a minimum requirement.

The Takeaway

Though observational studies have only the power to highlight patterns and connections, the significant long-term health trends highlighted hear warrant we think twice about the fiber in our diets.

“Usually, when people start new diets they’re thinking about just the short-term not the long term. Hopefully this review will encourage a shift in this way of thinking,” says dietitian Keri Gans M.S., R.D.N. owner of Keri Gans Nutrition. Whether you’re keto or eat a whole-grain-rich diet, this research reminds us that we need fiber for so much more than regular trips to the bathroom. In fact, it’s darn near essential for our survival.

Finally convinced to turn up your fiber intake? Gans recommends incorporating plenty of produce and fibrous whole grains into your every meal to ensure you meet your needs. Imagine oatmeal with berries for breakfast, a cruciferous salad for lunch, and a side of quinoa with dinner.

For more inspiration, check out 10 high-fiber foods that are so much better than prunes.

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