If health is important to you, Fiber must be respected with, well, every fiber of your being. This might seem to be a bit of an overstatement but as we elaborate on the subject, it will be clear that dietary fiber may well be the problem nutrient in your diet as well as the one that deserves the most attention.

Yes, fiber is a nutrient. While it may not provide us with energy, it is a critical component of a healthy diet. As nutrients go however, fiber isn’t very ‘sexy’ and so gets very little mainstream attention. Between many Americans believing the Steak is a good source of dietary fiber and the strong correlation of fiber intake with some of our biggest lifestyle disease risks, we believe that education on the subject is a public health issue.

Less than 3% of Americans get even the minimum recommended intake of dietary fiber and yet, we hear very little about this severely lacking part of our diet. What are the repercussions of this shortfall? What is fiber exactly and how does one go about getting more? We’ll try and answer these and other questions below: –

What is Fiber?

Fiber is the indigestible portion of plant foods like fruits, vegetables etc. The term ‘Fiber’ may be a bit misleading as not all dietary fiber is, well, fibrous. These are mainly carbohydrates that cannot be broken down immediately and used for energy (they do help feed good bacteria in the lower digestive tract). Fibers support the movement of food through the digestive tract and control the release of energy. They also provide water and bulk to waste materials which facilitates their expulsion from the body. They are divided into soluble and insoluble fiber, depending on whether or not they dissolve in water.

soluble and insoluble fiber

What is the daily requirement?

The minimum daily requirement is 31.5 grams. Currently the majority of the population fails to get even half the amount: –


Based on the information we uncovered while researching this article however, it may be beneficial to get 2-3 times the minimum amount. This is especially true if you’re interested in disease prevention or reversal. Our official recommendation is 50-75 grams, which is easily attainable by adding more whole fruit, vegetables and cereals to the diet. Based on data from cultures where cardiovascular disease is virtually absent, we think it’s a good idea to err on the side of more fiber than less. After all, we evolved eating ~100 grams of fiber per day as the following table illustrates: –


It would be wise to increase fiber intake gradually, allowing the body to adjust accordingly.

What are the risks of not getting enough Fiber? / What are the advantages of eating a high fiber diet?

High fiber diets are protective against heart disease, colon cancer, chronic bowel disease and diabetes among other common lifestyle related conditions such as obesity. While these concerns are serious, it doesn’t downplay the suffering caused due to constipation and related issues. If 50% of the adult American population increased dietary fiber intake by just 3 grams/day, the annual medical cost savings would exceed $2 billion. Increasing intake by 15 grams/day could potentially save a whopping $80 billion.

Reduced intake of fiber is linked to our most common diseases, many of which are the leading causes of mortality. It plays an important role in managing key aspects of several of these factors: –

Hormonal Imbalance

Many undesirable conditions are caused due to an excess of hormones. Take breast cancer in women for example, a common marker for which is increased estrogen levels. The body dumps this excess estrogen into the gut where it assumes that there will be enough fiber to flush it out of the system.


Unfortunately, as the images above show, we eat a lot less fiber as compared to our ancestors. This causes the excess hormone to be absorbed back into the body.
The situation also affects men as having low levels of estrogen is a good thing since it facilitates a positive testosterone balance.

Cholesterol Regulation and Heart disease

By the same mechanism that the body uses to get rid of excess estrogen, excess cholesterol is also eliminated. Provided you are eating enough fiber of course. Fiber speeds up the transit of materials through the intestine by providing bulk and dilutes the waste stream which facilitates the removal of excess cholesterol. After all, we evolved eating tons of fiber-rich plant food and so it is not surprising for the body to assume that there will be enough fiber to get the job done.


High cholesterol has been linked to every form of cardiovascular disease and is quite possibly the only real factor in the build-up of arterial plaque. While there is sufficient evidence to prove these protective effects, the best part is that a high fiber diet may even reverse an existing condition brought upon by high levels of bad cholesterol: –


Therefore, fiber can not only prevent heart disease but may also be used to treat it. Heart patients that increase their intake of fiber after their first heart attack can actually reduce their risk of a second.

Weight management/Obesity

We’ve spoken about Metabolic syndrome or ‘syndrome X’ in our weight loss article. There appears to be an inverse relation between metabolic syndrome, inflammation, obesity and dietary fiber: –

relation between metabolic syndrome, inflammation, obesity and dietary fiber

Of course, we all know that fiber provides bulk to food and plays a big part in meal satiety.

Diabetes, blood sugar/insulin regulation

Fiber delays the release of sugars in fruit for example and therefore lowers its standing on the glycemic index. This slow, gradual release also helps in keeping insulin levels optimal. High fiber diets may have a protective effect against insulin resistance, effectively preventing diabetes and reversing pre-diabetic conditions.

Crohn’s disease and ulcerative colitis

Crohn’s is an autoimmune disease that affects nearly 1.4 million Americans. Very little is known about this condition and there is currently no cure. Switching to a different diet has shown an impressive remission rate of the condition: –

impressive remission rate

These numbers are better than anything achieved by current drug treatments. High fiber and fruit intakes were associated with a decreased risk of Crohn’s disease and ulcerative colitis, which should be of note to anyone looking to avoid getting them in the first place.

Elimination of heavy metals

Heavy metals such as lead and cadmium can pose serious health risks if allowed to accumulate in the body. There is an increase in elimination of these metals on a more vegetarian diet than otherwise. This is due to plant components such as fiber inhibiting their absorption.

Stroke Prevention

Increased fiber intake has been associated with a decrease in stroke risk. This is due to the fact that reduced fiber intake may lead to stiff arteries which increases risk of stroke and as we’ve established above, fiber helps reduce cholesterol and blood sugar levels which further complements the effect.

Plenty of benefits then. How does this translate to athletic performance? Well, we hope you’ll agree that having impaired circulation, stiff arteries or poor digestion won’t do you favors in any sort of exercise related endeavor. Therefore, increasing your fiber intake is essential to optimal athletic performance.


Plant foods and fiber seem to produce these impressive effects almost interchangeably. Indeed, fruits, vegetables, grains and legumes are essentially the only real sources of fiber.


Oats seem to have particularly strong effects on blood vessel health: –


It is therefore possible to attribute some of the benefits of fiber to increased intake of whole plant-based food and vice versa. Fiber serves as a marker for increased plant consumption, however there are many bio-active components in them that may have these beneficial effects. Whatever the case may be, we hope everyone can agree on the following conclusions: –

  1. Fiber is a dietary component of utmost importance, despite being largely ignored by the mainstream.
  2. We should all eat a more plant-based diet.

References and Image sources

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Matt Williamson
My name is Matt - fitness freak by choice. I intensively study and write about nutrition and health related topics. After reading and researching intensively on human health, I aspire to proliferate the wisdom that I acquired in a simple way.