You're Probably Not Getting Enough Fiber — Here's Why it Matters and How to Fix It

While many people, particularly those cutting back on meat, are usually concerned about whether they're getting enough protein, the fact of the matter is, there's another macronutrient most people should be far more focused on: while most Americans (even those eating plant-based) are getting enough protein, fewer than five percent of Americans are getting the recommended 25 to 30 grams of fiber per day.

"Protein deficiency is almost unheard of in America," says Anna Mitchell, a Registered Dietitian and owner of Nutrition with Anna LLC. "Yet most Americans are focusing their energy on protein."

For Julie Miller Jones, PhD, LN, CNS, an emeritus professor of nutrition at St. Catherine University in St. Paul, MN, and a member of the Grain Foods Foundation's Scientific Advisory Board, this is particularly worrisome in some subsets of the population. Jones notes that fewer than one percent of males between 14 and 55 years old are actually meeting their recommended daily intake for fiber.

And this holds even more true for those on restrictive diets like keto or gluten-free, explains Jaclyn Sklaver, MS, CNS, LDN, CISSN-Sports Nutritionist, and founder of Athleats Nutrition. The lack of whole grains and adequate fruits and vegetables while doing these diets can make meeting recommended fiber intake an elusive goal — and pose serious health risks as a result.

Why Is Fiber So Important?

Fiber is known for keeping you full and regular, but it does so much more than that. Not only are the brain and gut linked, meaning that fiber intake contributes to improved mood and mental health, but fiber is also an important factor in the management of weight thanks to improved satiety. "In the obesity fight, foods high in fiber improve satiety, which may help in averting obesity and helping dieters stick to their diets," explains Jones.

Consuming enough fiber can even reduce risk and symptoms of diabetes, according to Irazema Garcia, Diabetes Prevention Program (DPP) coach with First Mile Care, a Silicon Valley-based preventative chronic care company. "Fiber plays a role in glucose regulation, it can slow down the rate at which glucose is absorbed, aids in the detoxification process through regular bowel movements, and helps with satiety, which can lead to maintaining a healthy weight," says Garcia.

Studies have linked adequate fiber consumption with a reduced risk of cardiovascular disease, type 2 diabetes, heart disease, strokes and colorectal cancer. Jones adds that fiber is "critical" to a healthy microbiome and can reduce the risk of "nearly all chronic diseases."

Soluble vs. Insoluble Fiber: What's the Difference, and Do You Need Both?

Within the category of fiber, there are two major sub-categories: soluble and insoluble. The former, as its name suggests, dissolves in water, taking on a gel-like consistency that, Garcia explains, helps to keep you feeling full for a longer period of time.

Insoluble fiber, meanwhile, does not dissolve in the body. Rather, it adds bulk to stool, helping to move food through the digestive tract and promote regular bowel movements. This, explains Dr. Eudene Harry, an integrative and preventative medicine practitioner and former ER physician, can prevent constipation and reduce risk of conditions such as diverticulitis.

Jones says, "Most basically, insoluble fibers help with digestive functioning and feelings of fullness, while soluble fibers, especially gummy ones, can also impart satiety and do things like trap glucose and cholesterol to slow or inhibit their digestion and absorption."

On average, about three-quarters of fiber should be insoluble fiber, and one-quarter should be soluble, according to Claudia Hleap, RD, LD. Though Garcia adds that it is important to listen to your body's individual needs, "Our bodies work differently, and no two people will respond quite the same way."

How to Add Fiber to Your Diet

In an ideal world, our experts are unanimous: fiber should be gleaned from food. Luckily, high-fiber foods and recipes are not at all hard to come by!

Soluble fibers are found in oats, barley, nuts, seeds, lentils, legumes, and fruits. Chia seeds are also a fantastic source of soluble fiber, as in this tasty chia seed pudding, and Garcia recommends getting familiar with flax meal, which can be sprinkled on salads and soups, blended into delicious smoothies, or baked into crisp crackers. Perennial favorite avocado is an excellent source as well, so enjoy it in delicious guacamole or spread on whole-grain toast.

Insoluble fiber, meanwhile, can be found in nuts, seeds, and skin-on fruits and veggies. Leave the skin on the apples in this apple-walnut salad, or toss together a farro salad with cherries, apples, and nuts for a fiber-rich lunch.

At the end of the day, says Garcia, "The best fiber-rich foods are the ones you will actually eat. There is no nutritional benefit to buying fiber-dense food that will sit on the counter and spoil. Be realistic in your purchases and buy foods that will be eaten."

Of course, there are some side effects of adding fiber to your diet. (Yep, we're gonna talk about gas.) The secret is to take things slow: ramp up your fiber intake progressively, so that you can adjust to the change bit by bit. "Eating too much fiber at once is overwhelming to your digestive system and good bacteria, so you may experience bloating and gas," explains Emily Danckers, MS, RD, founder of Emily RD Nutrition Coaching. "However, as your body adjusts to a higher fiber diet, your gut bacteria increase and diversify, which may alleviate these negative side effects of eating a lot of fiber."

Fiber Supplements: A Last Resort (for Most)

Our experts all recommend adding fiber from food sources whenever possible. According to Harry, adding fiber from foods isn't just a more balanced approach — it also makes it difficult to ingest too much, leading not just to digestive discomfort, but the possibility of hindering the body's absorption of minerals like zinc or iron.

But if you're unable to add enough fiber to your diet naturally, a supplement can be one way to help. "I recommend fiber supplements to anybody who has slow digestion such as constipation or IBS-C, anybody who is on a gluten-free, calorie restricted, or ketogenic diet because they have almost no fiber in their diets," says Sklaver. "I will also recommend it to people who have high cholesterol or [are] trying to manage their blood sugar such as diabetics or prediabetics."

Sklaver's brand of choice is NOW, which makes plant-based acacia fiber that has little flavor and dissolves well in water. Jones, meanwhile, recommends psyllium (Metamucil or Konsyl) for constipation or issues linked to cholesterol or glucose reduction; Benefiber, meanwhile, may be helpful with managing blood sugar. While Hleap says she "rarely" recommends supplements, when she does, she, too, relies on Metamucil or Benefiber.

Ultimately, though, Jones notes that while "high-fiber foods are cheaper, better tasting, and much more fun than supplements," if you choose to go the supplement route, "the most important thing is to find one that is well tolerated by your gut and your pocketbook."

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• Our Best High-Fiber Recipes