Fiber is a dietary superhero. Are you eating enough of it?

I have a confession to make: I am a fiber fanatic.

I sometimes think of fiber as the Peter Parker of food — a seemingly boring, nerdy nutrient that's actually secretly a dietary superhero.

Fiber does so much more than just help keep us regular. For starters, it helps control blood sugar levels and lower cholesterol and inflammation.

In fact, one review of 185 studies and of dozens of clinical trials found that diets rich in fiber were linked to a lower risk of major health problems, including obesity, Type 2 diabetes, certain cancers and cardiovascular disease.

One reason that fiber is so important to good health is that it provides the primary fuel for the trillions of microbes that live in your gut. These gut microbes ferment the fiber, breaking it down to produce beneficial chemical messengers that influence your health throughout your body.

But Americans aren't eating enough fiber. According to the U.S. government's dietary guidelines, you should be eating 14 grams of fiber for every 1,000 calories you take in daily. But only around 9% of women and 3% of men in the U.S. meet the fiber recommendations.

So how do we add more fiber to our diets?

I spoke to Hannah Holscher, a nutrition and gut microbiome researcher at the University of Illinois, and Justin Sonnenburg, a gut microbiome researcher at Stanford University and co-author of the book The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-Term Health. Here's their advice on how to start adding more fiber to your diet.

1. Focus on getting fiber from a variety of plant-based foods

Researchers say your best bet is to get fiber from a variety of plant-based foods. That means eating different kinds of fruits and vegetables, whole grains, beans, seeds and nuts. Think sweet potatoes, avocados, pears, asparagus, brown rice, lentils and pumpkin seeds. Not only are these foods a good source of fiber, but they also contain other vitamins, minerals and phytonutrients that promote good health.

Experts say supplements can be helpful, but they shouldn't be your primary source of fiber. (If you take fiber supplements, check with your doctor to make sure they don't interfere with any medications you are taking.)

2. Rethink your salads

Swap around some of your salad ingredients. For instance, while iceberg lettuce has almost no fiber, subbing in cabbage or kale serves up a bit more. To really ramp up the fiber, toss in an artichoke (a medium one serves up 7 grams of fiber) or some roasted Brussels sprouts (which contain around 6 grams of fiber per cup). Or top off your greens with some chickpeas (they pack around 3 grams of fiber per one-fourth cup).

3. Give your meals an extra boost

Adding more fiber into your daily habits doesn't have to be hard. Some surprisingly snackable foods are high in fiber, like avocados. Add slices to a sandwich, or grab a side of guac with your tacos. Munch on some air-popped popcorn (nearly 6 grams of fiber in 3 cups). Sprinkle some chia seeds, which serve up around 4 grams of fiber per tablespoon, on your yogurt. Top off oatmeal or salads with walnuts or almonds. Or throw a cup of cooked kale, which has about 4 grams of fiber, into a lentil soup for a fiber-full meal.

4. Target high-fiber foods

If you want to maximize your fiber bang for your buck, check out this chart from the U.S. Department of Agriculture for some ideas of foods that pack a powerful fiber punch. You might be surprised to learn that just a half-cup of artichoke delivers nearly 5 grams of fiber and a cup of cooked sweet potatoes contains 6 grams of fiber.

5. Check out the freezer aisle

Raspberries and blackberries are some of my favorite sources of fiber — one cup of either has about 8 grams. But they can be expensive. So I buy them frozen as well as fresh. Frozen berries tend to be cheaper, last a lot longer and are great to blend into smoothies.

I also like to keep frozen artichokes and spinach on hand. Try sautéing them together with a bit of olive oil; then add in a dollop of goat cheese. This combo makes for a delicious topping for salmon or sea bass.

6. Take baby steps

If you don't eat a lot of fiber, the key is to start slowly. That's because high-fiber diets can cause gas and bloating in some people. The gas is a byproduct of the fermentation of fiber by the microbes in your gut. You want to be gradual about increasing your fiber intake in order to give your gastrointestinal tract time to adjust.

For example, if you like to eat white bread, try swapping out one serving per week with whole grain bread. The second week, eat two servings. Keep doing that until you've swapped all your servings of white bread to whole grain.

7. Keep track of how high-fiber foods affect you

As you increase your fiber intake, you may want to jot down how various high-fiber foods affect you. Everyone is different, and some folks might be more sensitive to certain types of fiber than others. For instance, I love chia seeds, but if I have more than 2 tablespoons in a day, my GI tract protests.

8. Don't forget to drink water

As you add more fiber to your diet, make sure to drink plenty of water as well. It can help the fiber move through your system and keep it from hardening, which can lead to more gas and constipation.

Listen to the full podcast episode to hear more about how fiber affects the gut microbiome — and for more tips on how to add fiber into your daily diet.

The audio portion of this episode was edited by Sylvie Douglis and produced and fact-checked by Clare Marie Schneider. The digital story was edited by Malaka Gharib. The visual producer is Kaz Fantone. We'd love to hear from you. Leave us a voicemail at 202-216-9823, or email us at LifeKit@npr.org.

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