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Do You Eat Enough Fiber?

Zoe Schilling

PharmD. Candidate, 2022


Did you know the recommended daily fiber intake is 25-40 grams per day? Unfortunately, most Americans consume roughly 16 grams each day. If this describes you, then you could be missing out on the many wonderful benefits of fiber.

Health Benefits of Fiber:

-regulate digestion

-improve bowel movements

-lose weight

-balance cholesterol

-regulate gut microbiome

-and more! What is Fiber?

Fiber is a non-digestible carbohydrate that your body cannot break down, so it passes through the body without counting towards calories. In other words, fiber is essentially “zero calories.” However, fiber produces several positive impacts in your digestive tract and adds “bulk” to your food which produces satiation and keeps you feel full longer. Some common healthy sources of fiber include whole grains, nuts and seeds, as well as fruits and vegetables.

Soluble verses Insoluble Fiber:

Fiber comes in two varieties: insoluble and soluble. Insoluble fiber is found in whole grains, wheat cereals, and vegetables such as carrots, celery, and tomatoes. Soluble fiber sources include barley, oatmeal, beans, nuts, and fruits such as apples, berries, citrus fruits, and pears. Both soluble and insoluble fiber are positively linked to heart health and improved gut microbiome.

Recommended intake:

Women should try to eat at least 21 to 25 grams of fiber per day, while men should aim for 30 to 38 grams per day.

Here is a nice link to the CDC’s website with a helpful chart displaying high fiber foods and serving size recommendations:

Fiber Aids Digestion and Helps Regulate Bowel Movements:

Fiber works by both "bulking up: the stool and retaining water. Dietary fiber increases the weight and size of your stool. It can also soften your stool, thus helping you more easily defecate. Likewise, it will be easier for you to remove toxins and other wastes from your body. If you’ve ever taken the over-the-counter constipation medication “Metamucil” this is exactly how this drug works.

Fiber Leads to Weight Loss:

Sources of dietary fiber are shown to lead to weight loss because fiber is filling and not absorbed by the body in terms of calories. When you eat more high-fiber foods, you have less room in your diet for foods that are not as nutrient-dense, such as refined carbohydrates. Hence, fiber provides satiation, or the “hunger-satisfying” feeling. Think your tummy gets volume added, expands in your stomach, and then you are not as hungry as soon after or during a meal.

(Think about how you feel about eating a pasta dinner with white bread and chocolate cake for dessert… extremely full temporarily, but hungry again 1-2 hours later right? That is because that meal is heavily weighted in refined carbohydrates, and little to no fiber.

Compare that to a big spinach and kale salad with avocado, flax seeds, carrots, celery, chicken with an apple for lunch… you may not be hungry for 4-5 hours due to the heavy fiber content in that meal)

Fitness tip: Eat vegetables with EVERY meal and drink 1-2 cups of water with EVERY meal.

Gut Microbiome Benefits:

This is a really complicated topic and rather difficult to comprehend, but basically all you need to know is that your body has trillions of organisms like bacteria, fungi, viruses, and other forms of life that collectively make up your gut microbiome. Don’t be scared, we actually NEED certain organisms in our guts to be fully healthy. Everyone has these gut microbiota- some more bad organisms than good, hence the rising prevalence of gastrointestinal diseases like celiac disease, inflammatory bowel syndrome, small intestinal bacterial overgrowth (SIBO), etc.

Dietary fibers, are subjected to bacterial fermentation in the gastrointestinal tract and can impact the gut metabolic activities. The small intestine cannot digest fiber. Instead, it passes into the colon, where microbes are able to break the fiber down. This process results in the production of short-chain fatty acids (SCFAs). Experts believe these SCFAs are important for many factors which can positively impact health.

If you are still interested in this subject, I highly recommend you watch this YouTube video of Dr. Sonnenburg, the bestselling author of The Good Gut:

A recent study published in Cell Press on July 12, 2021 demonstrated how high-fiber diets increased microbiome-encoded glycan-degrading carbohydrate active enzymes (CAZymes). Additionally, the high-fermented-food diet steadily increased microbiota diversity and decreased inflammatory markers. In lay-person terms, this study shows how certain foods can help produce more GOOD bacteria, eliminate bad bacteria, and improve overall gut microbiome.

Wastyk HC, Fragiadakis GK, Perelman D, et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021;184(16):4137-4153.e14. doi:10.1016/j.cell.2021.06.019

Dr. Katrine Whiteson, the co-director of the University of California, Irvine (UCI) Microbiome Initiative says that the “lack of fiber intake in the industrialized world is starving our gut microbes, with important health consequences that may be associated with increases in colorectal cancer, autoimmune diseases, and even decreased vaccine efficacy and response to cancer immunotherapy.”


· If you are constantly hungry or suffer from some sort of gut imbalance or gastrointestinal disorder, fiber could positively impact your health in many ways.

· By adding “bulk” to your food volume, fiber helps keep you full for longer amounts of time and can therefore help you lose weight by eating less.

· Fiber increases the weight and size of your stool, relieving constipation and removing toxins from the body.

· Fiber helps produce more “good” bacteria in your gut and restores normal gut microbiota which can lead to improvement in chronic disease states and reduce inflammation.



Holscher HD. Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut Microbes. 2017;8(2):172-184. doi:10.1080/19490976.2017.1290756

Wastyk HC, Fragiadakis GK, Perelman D, et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021;184(16):4137-4153.e14. doi:10.1016/j.cell.2021.06.019

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