Introduction
Fiber is a type of carbohydrate that the human body is unable to fully digest. It comes almost exclusively from plants and is considered a very important part of the human diet, especially for the microbiome and for overall human health. This NutriWiki will dive into the different types of fiber, how much you should consume, and whether to count them toward your daily carbohydrate intake.
Summary
Fiber is a type of indigestible carbohydrate. It is often categorized as soluble fiber or insoluble fiber. Its intake is associated with lower risks of chronic disease, but it is not entirely clear whether that is due to the fiber itself, or the overall dietary pattern that comes with higher fiber intake. Fiber intake appears to be especially important for colon health. The current guidelines recommend roughly 14 grams per 1,000 kcals per day.
Discussion
What is fiber?
Fiber is a type of carbohydrate, specifically a polysaccharide (meaning many sugars), that is found in almost exclusively in plants. It is often categorized into two major categories: soluble fiber and insoluble fiber. Soluble forms are considered soluble in water and often turns into a “gel-like” substance and slow down digestion. Insoluble forms are not soluble in water and often stimulates the gastrointestinal tract and is important for digestion, but too much can also cause issues.
It is most often found in fruits and vegetables, as well as many whole grain products such as wheat, oatmeal, and barley. It is also found in nuts, some seeds (e.g. flax seeds), as well as in a wide variety of legumes (aka beans).
How much do you really need?
Guidelines used to be based on male vs female, but the rationale for that was actually based on calorie intake, with males, on average, requiring more calories than females. However, those guidelines have been updated to be more in line with individual caloric intake.
The most current guidelines recommend roughly 14 grams per 1,000 kcals per day. However, some individuals may require more or less depending on their digestive needs. Some conditions such as IBS or diverticulitis can also alter the daily requirements.
Do I count fiber toward my carbohydrate macros?
As fiber is not digestible, we do not really get meaningful calories from it. Some of it may be digested by your microbiome and turned into short-chain fatty acids, but in humans this caloric content is minimal. As such, there is a question of, “Should we include them in our daily macros and calorie count”.
The answer is, it depends, but be consistent. We generally recommend that individuals do include these in their total calorie count as we find that most people don’t need to really worry about net carbs as the difference between total calorie intake in a day from net carbs and total carbs is fairly minimal. For more information see our NutriWiki article on this very topic!
Is there such a thing as too much fiber?
Yes. Too much can cause gastrointestinal issues. This can occur in people consuming very high fiber diets, or even just in people going from low fiber diets to moderate fiber diets as any large change in intake can cause gastrointestinal issues.
If you are consuming a diet that lower in fiber consider slowly increasing the intake instead of jumping right to the recommendations/guidelines. If you are consuming more than the guidelines, considering slowly decreasing the total intake until you are closer to the guidelines/recommendations.