Fiber helps feed beneficial gut bacteria. It speeds up digestion. It can change how other nutrients and chemicals are absorbed by the body. And some types of fiber absorb water in the digestive tract and help avoid constipation.

In fact, eating enough fiber is absolutely crucial to maintaining a healthy digestive system. And maintaining a healthy digestive system is central to overall well-being. 

The average healthy male under the age of 50 is supposed to eat as much as 38 grams of fiber a day — the equivalent of five full portions of kidney beans — and for women, the figure is 25 grams.

But there's more to think about than just how much fiber you are getting, namely how many different types. Because the term "dietary fiber" covers a wide range of different plant-based substances that your body needs to function healthily, I recommend to my clients that they eat a broad mix of different high-fiber foods. 

Incorporating the following foods high in fiber into your diet is a great place to start.

High fiber breakfast cereals

One of the reasons why breakfast is so essential to losing weight is that it's an easy time to introduce whole grains. Many common breakfast cereals — from Grape-Nuts to Shredded Wheat to Fiber One — are extremely high in fiber, and there are plenty of organic and/or all natural alternatives on the market for those trying to eat more sustainably too. (Your local farmers market can be a great place to pick up locally made granola.)

Keep in mind though, many breakfast cereals that tout their whole grain credentials are extremely high in sugar. The less processed a whole grain is, the better. Look for cereals that have at least 5 grams of fiber per serving on the nutritional label, and fewer than 25 percent of their calories from sugar — unless dried fruit is a major component. If cereal isn't your thing for breakfast, try whole grain muffins, toast, pancakes or waffles as an alternative to refined flour products. 

Beans, beans, beans

One of the best ways to eat more fiber is to incorporate more legumes into your diet. A portion of cooked kidney beans or lentils contains nearly 8 grams of fiber, and canned chickpeas or baked beans aren't too far behind. Try adding them as an addition to soups, stews and salads, or you could even explore recipes that use them as a main ingredient. One of my family's favorite meals is a simple dish of linguine, chickpeas, olive oil, parsley and lemon zest — sprinkled with a generous dose of Parmesan — and we've also recently discovered the joy of lentil tacos. (Really, they are delicious.) While I try to encourage my clients to eat minimally processed foods where possible, you can also find many foods containing legumes in the vegetarian section of the freezer aisle. Black bean burgers, for example, are an easy go-to snack when you're in a hurry.

Be warned though, as with any high fiber food, a rapid increase in consumption can lead to bloating and discomfort. Be sure to gradually increase the amount of legumes you are eating so your digestive system can acclimatize, and drink plenty of fluid — at least eight cups of water is the recommended amount. 

Fruits and vegetables

It goes without saying that we should all be eating more fruits and vegetables. Besides the vitamins, minerals and other micro-nutrients they contain, fruits and veggies are also one of the best sources of both soluble and insoluble fiber. Pear, sweet potato, and green peas are all considered high in fiber — as are apples, berries and even dried fruit, such as dates. To make sure you get a good dose of dietary fiber with your fruits and veggies, follow the standard nutrition advice to "eat the rainbow" (in other words, eat a wide variety of fruits and veggies), and be sure to eat them with the skin on where possible. Like beans, eating a side of veggies is a good place to start — but why not consider replacing a few meat-centric meals with vegetable-based entrees a couple of times a week? There's no shortage of delicious vegetarian and vegan recipes available these days to help you get started. 

Whole grains

Working more high fiber whole grains into your diet doesn't have to mean abandoning white bread or pasta all together. In fact, I often advise clients to start slowly, and to aim for half of your grain intake from whole grains. (Replacing all grains with whole grains can lead to getting too full too easily, meaning you don't eat some of the other important nutrients you need for health.) Consider replacing one or two portions of grain a day with a diverse range of whole grains — these might include whole grain wheat, quinoa, rice, oats, bran etc. If you find the flavor and texture a little intense, you can start by mixing whole grain and white pasta, or both brown and white rice together. You can also seek out breads made with a mix of different grains. My family really enjoys some of the sprouted grain breads available on the market these days. 

High fiber snack foods

From no-salt-added spelt pretzels to mixed vegetable chips, there are plenty of higher-fiber snack foods on the market these days. Even a bowl of peanuts, almonds or popcorn can be a good source of additional fiber. As I mention above, I would never encourage clients to focus on snack or processed foods for a significant portion of their daily needs, but if you are going to snack anyway, why not make sure your body is getting something out of it too? In general, aim for a minimally processed, low-sodium snack (you can get unsalted, unadulterated nuts in the bulk aisle at your supermarket), and make sure your snacking doesn't interfere with eating a full, healthy meal (with lots of fruits and veggies!) three times a day. 

Jenni Grover, MS RD LDN, is a registered dietitian and co-founder of Realistic Nutrition Partners in Durham, N.C. She specializes in child, maternal and prenatal nutrition, with a focus on whole foods.

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