What Is the Best Time of Day to Eat Fiber?

March 30, 2022

One reason fruits and vegetables are good for you is because they have dietary fiber. Even though not a nutrient, fiber is absolutely necessary for digestion, metabolic health, and immunity, among other things. That’s why you’ll see that all health guidelines mention increasing fiber intake for good health.

And while you probably already know you should be eating more fiber — polls show people in developed nations are eating half of the recommended daily intake — what may be less clear is when is the best time of day to do so.

Does eating fiber in the morning provide more benefits than at dinner time? The answer may surprise you. But before we answer that, here’s a quick primer on fiber and its importance.

What Is Fiber?

Put simply, fiber refers to non-digestible carbohydrates. Another way to define fiber is as complex carbohydrates that can’t be broken down by digestive enzymes. Fiber comes in many different forms but is roughly divided into:

Soluble fiber. This type dissolves in water to form a gel-like material and is fermented by beneficial bacteria, mostly in the colon. Fruits and vegetables are the main sources of soluble fiber.

Insoluble fiber. This type does not dissolve in water and is not always fermented by gut bacteria. Cereals and whole grains are the main sources of insoluble fiber.

You need both types in your diet since each type provides unique benefits. Soluble fiber, for example, increases the number and variety of beneficial gut bacteria. It also traps and eliminates bile in the digestive tract, which helps lower blood cholesterol levels. Insoluble fiber, on the other hand, helps prevent constipation.

Fiber intake has greatly decreased over the last two centuries with industrialization and the introduction of ultra-processed foods that are devoid of fiber. As a result, there has been a sharp rise in diabetes, dyslipidemia, high blood pressure, and heart disease in the general population. Paying attention to your fiber intake can help you avoid and treat these health problems.

Increasing Fiber Intake

A survey by the International Food Information Council found that most people know fiber is good and are striving to eat more of it. However, the same survey also found that many people overestimate their fiber intake, usually due to misleading food labeling. More specifically, it found that Americans eat around 15 g of fiber daily, or half of what the Institute of Medicine recommends (19 to 30 g per day, depending on age and sex).

To avoid this fiber gap, make sure your daily diet includes foods like:

Whole grains
Beans, lentils, and other legumes
Nuts and seeds
Fruits and vegetables

Whole grains are the most important source of fiber in western diets, providing more fiber per edible portion than fruits and vegetables. Barley, for instance, is particularly rich in fiber at 17g in a 100-g serving.

You can also get additional fiber in supplement form, like psyllium husk, inulin, methylcellulose, wheat dextrin, or yellow pea fiber. You can also get fiber from healthy convenience foods that have been fortified with fiber. Although, it’s best to get the majority of your daily fiber directly from whole foods as these contain different kinds of fiber.

Should I Eat Fiber in the Morning or at Night?

In a nutshell, any time of day is good enough for fiber. There really is no ideal time for fiber intake as fiber should be included with every meal. Nutrition experts generally advise spreading out fiber evenly throughout the day. Too much fiber during a single meal can cause side effects, like bloating, gas, abdominal pain, and constipation.

Eating 5 to 10 g of fiber with each meal is one way to go about this. This is usually how much is found in a single serving of plant foods. To track your fiber intake, use the Nutrition Facts labels to see how much fiber is in a serving of packaged food or see the USDA National Nutrient Database to check the fiber content of whole foods.

There are, however, different benefits to eating fiber in the morning than in the evening. Studies show that a fiber-rich breakfast leads to greater feelings of fullness throughout the day. On the other hand, fiber-filled dinners could help improve sleep quality according to a 2016 clinical trial on 26 adults. But all in all, fiber intake provides nothing but benefits when taken moderately, consistently, and throughout the day.

What About Fiber Supplements?

Manufacturers of fiber supplements or foods fortified with fiber generally provide instructions on how to consume their products. In most cases, they say to take a fiber supplement with a meal. Other than that, there is generally no best time in a day for these products.

You may, however, want to consider taking a fiber supplement with a meal that’s low in or completely lacks fiber. Depending on the type of supplements, it’s a good idea to drink plenty of fluids as many of these products use soluble fiber. Soluble fiber can cause constipation when taken in excess or without enough fluid intake.

Another thing to keep in mind is to not take certain fiber supplements at the same time as medication. Some fiber supplements are used as laxatives or have a laxative effect at certain doses. They may speed up digestion to prevent drugs from being properly absorbed.

Keep in mind that supplements should not be your main source of fiber. Get most of your fiber from whole foods and supplement only at certain times during the day. You need both soluble and insoluble fiber in balanced amounts to get the most benefits.

Summary

To recap, the best time of day to eat your fiber is anytime. Fiber is an essential component of a healthy diet that should be taken with every meal. Eaten in the morning, it helps you feel full throughout the day. Consumed before bedtime, fiber helps you sleep better.

If you take fiber supplements, choose to eat them with a meal that is low in fiber and can use a boost. Also, avoid fiber supplements that have a laxative effect when taking medication. Otherwise, stick to whole and fortified foods as your main source of dietary fiber for optimal digestion, health, and well-being.

References:

Quagliani D, Felt-Gunderson P. Closing America's Fiber Intake Gap: Communication Strategies From a Food and Fiber Summit. Am J Lifestyle Med. 2016;11(1):80-85. Published 2016 Jul 7. doi:10.1177/1559827615588079

McRorie JW Jr, McKeown NM. Understanding the Physics of Functional Fibers in the Gastrointestinal Tract: An Evidence-Based Approach to Resolving Enduring Misconceptions about Insoluble and Soluble Fiber. J Acad Nutr Diet. 2017;117(2):251-264. doi:10.1016/j.jand.2016.09.021

Uzhova I, Mullally D, Peñalvo JL, Gibney ER. Regularity of Breakfast Consumption and Diet: Insights from National Adult Nutrition Survey. Nutrients. 2018;10(11):1578. Published 2018 Oct 26. doi:10.3390/nu10111578

Yannakoulia M, Aggelopoulou D, Skenderi K, Koinaki S, Yiannakouris N. A Mediterranean-like breakfast affects energy intake and appetite-related feelings. Int J Food Sci Nutr. 2014;65(7):899-902. doi:10.3109/09637486.2014.931359

St-Onge MP, Roberts A, Shechter A, Choudhury AR. Fiber and Saturated Fat Are Associated with Sleep Arousals and Slow Wave Sleep. J Clin Sleep Med. 2016;12(1):19-24. doi:10.5664/jcsm.5384

González Canga A, Fernández Martínez N, Sahagún Prieto AM, et al. Dietary fiber and its interaction with drugs. Nutr Hosp. 2010;25(4):535-539. https://pubmed.ncbi.nlm.nih.gov/20694287/