The importance of eating plenty of fiber is not exactly a new concept. Facts: It improves digestion and helps prevent disease—and you probably need to consume more of it.

The daily recommended fiber intake for adults is 25 to 38 grams, but the average person only hits about 17 grams a day, says Wendy Dahl, Ph.D., an associate professor at the University of Florida who researches fiber, probiotics, and the microbiome in health and disease.

Though we can’t digest fiber ourselves, the trillions of microbes in our digestive tract can—and we reap plenty of health benefits in the process, Dahl explains.

“High-fiber diets are associated with decreasing the risk of so many chronic diseases,” says Dahl. (Think diabetes, heart disease, even cancer.) “They’re even linked to lowering all-cause mortality.” Given this, Dah believes eating fiber-filled plant foods is one of the best things you can do for your health.

Although everyone needs fiber for optimal health, a select few groups can really benefit from a conscious effort to increase their intake. Here’s who—and why.

1. People With IBS

People with IBS (including IBS-C, IBS-D, or a combination of both) might be wary of adding anything that might mess with their digestion to their diet. However, fiber has been proven time and again to improve the symptoms of IBS. Fiber acts as a bulking and softening agent, making intestine motility easier, according to research published in the International Journal of Molecular Medicine.

That said, some people with IBS may be extra sensitive to certain high-fiber foods, like raw vegetables, nuts, and beans. “Natural food sources are best, but they can lead to gas, bloating, and indigestion for many of us,” says dietitian Nancy Farrell Allen, R.D.N., Academy of Nutrition and Dietetics Spokesperson.

Read More: 10 High-Fiber Foods You’ll Actually Enjoy Eating

For these people, fiber supplements are a great way to access the benefits of fiber without wreaking havoc. “The benefit of supplements is that some are non-gelling or gluten-free, offering a lower risk of uncomfortable indigestion,” Allen says.

A supplement shouldn’t replace healthy foods—but it does offer a useful boost if you’re wary of introducing more foods.

If you deal with constipation, Dahl specifically recommends an insoluble fiber supplement (like wheat, rye, or oat bran), which can support laxation.

2. People With High Cholesterol

Your body needs cholesterol to function, but a high amount of LDL (a.k.a. “bad cholesterol”) can be hard on the body. (It raises your risk for heart disease and stroke, the CDC says.)

However, fiber can help decrease high cholesterol, according to research published in the American Journal of Clinical Nutrition. This effect occurs through one of its many health-enhancing mechanisms: reductions in bile acid reabsorption. Basically, this means that less cholesterol gets into the bloodstream.

Read More: Everything You’ve Ever Wondered About Cholesterol, Explained

Plus, “mounting research suggests a relationship between dietary fiber intake and inflammatory status,” says Dahl. This, too, could be huge for fiber’s role in cholesterol and overall health.

To support healthy cholesterol, consider adding a water-soluble fiber supplement—like psyllium—to your routine to boost your overall intake. 

3. People With High Blood Pressure

Similarly, fiber intake is also associated with decreasing high blood pressure and its adverse health effects. Large-scale research (like this JAMA Internal Medicine meta-analysis) suggests it’s is crucial for preventing high blood pressure, too.

How? Research points to several of fiber’s many functions, including its impact on digestion and food absorption and association with lower body weight. 

Though different types of fiber (think soluble versus insoluble) may offer specific benefits, the key here is to consume a mix. “Most whole foods contain a mix of both of these,” says Dahl. “Choosing whole grains, beans, fruit, vegetables, nuts, and seeds will provide a perfect balance.”

Make sure you’re hitting at least 25 to 38 grams per day and talk to your doctor or nutritionist about whether you may need even more.

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