Fiber
What is Fiber?
Fiber is a necessary part of the diet that helps keep you full, reduces the risk of developing chronic diseases, and has many health benefits. Many children with ASD do not meet daily fiber needs. Increasing dietary fiber can help improve digestive health, promote a healthy weight, and control blood sugars.
Foods containing can help keep you fuller longer, and they also feed the good bacteria in your gut!
Due to picky eating and the decreased intake of fruits and vegetables, many kids with autism don’t get enough fiber, which is a common cause of constipation.
Fiber can help reduce risk of many chronic diseases like heart disease, diabetes, and cancer, hypertension, stroke, GI disorders, and obesity. [1-2]
Soluble vs Insoluble Fiber
Soluble Fiber
Soluble fibers dissolve in water → create a gel when digested
Increases the time it takes for food to pass through GI tract and may delay the absorption of some nutrients, which can help reduce serum cholesterol, keep you fuller longer, and stabilize blood glucose levels. [1]
More easily fermented by bacteria in the gut
Examples:
Beta-glucans: found in oats and barley; effective in reducing serum cholesterol
Pectin: used to make jellies and jams
Gums: commonly used as stabilizers in ice cream or other frozen desserts
Guar gum
Xanthan gum
Insoluble Fiber
Insoluble fiber does not dissolve in water.
Increases the bulk of stool → decreases the time it takes for food to move through the GI tract
Often used to treat constipation
Examples:
Lignin: only non-carbohydrate fiber source; makes up the “woody” texture of vegetables, like celery
Cellulose & hemicellulose: make up the cell walls of plants
Functional Fiber
Functional fiber is a nondigestible carbohydrate that has been extracted or isolated from a plant and has been shown to have health benefits. [2]
Unfortunately, both children and adults on average do not get enough fiber. This is due to the lack of consumption of good dietary sources, such as whole grains, fruits and vegetables, legumes, and nuts. [2]
Food Sources of Fiber
Foods typically contain a combination of both soluble and insoluble fibers, though some have more of one type than the other, such as:
Soluble Fiber
Nuts & seeds
Oat bran & oats
Citrus fruits
Broccoli & sweet potatoes
Insoluble Fiber
**Animal products do not contain fiber** [1]
Source: Autism Dietitian Instagram
Recommended Intake
These recommendations are based on the Dietary Reference Intakes (DRI), a general term for a set of reference values used to plan and assess the nutrient intakes of healthy individuals. [3]
Males
o-12 months: NA
1-3 years: 19 grams/day
4-8 years: 25 g/d
9-13 years: 31 g/d
14-18 years: 38 g/d
19-50 years: 38 g/d
51+ years: 30 g/d
Females
o-12 months: NA
1-3 years: 19 g/d
4-8 years: 25 g/d
9-13 years: 26 g/d
14-18 years: 26 g/d
19-50 years: 25 g/d
51+ years: 21 g/d
Under-Consumption of Fiber
Too little fiber in the diet can lead to constipation and risk of developing diverticulitis (inflammation of part of the digestive tract, usually in the large intestine).
One study found that specific fibrous foods, such as apples, pears, and prunes were helpful in reducing the risk of diverticulitis. [4]
A low fiber intake long term can increase the risk of developing chronic diseases and obesity.
Children who are picky eaters and typically eat foods high in carbohydrates but low in fiber are at risk for eating too little fiber.
Over-Consumption of Fiber
An overconsumption of fiber in the diet can lead to diarrhea or constipation, bloating and gas, or abdominal discomfort.
Children who eat an excessive amount of oats and whole grains, fruits, and vegetables are at risk for over consuming fiber.
Supplements
Fiber supplements are often used for the treatment of constipation. Below are two commonly used fiber supplements and their benefits.
Psyllium
Psyllium is often used in the treatment of constipation. It brings water into the intestine, increasing the water in the stool, making it easier to pass. [5]
One study found that psyllium supplementation in constipated patients improved their intestinal microbiota. [5]
Inulin is naturally present in foods such as garlic, onions, wheat, artichokes, and bananas. It is often used to improve taste in certain applications; it is also often used in the form of a supplement due to its nutritional benefits. [6]
Studies have shown that inulin contributes to the health of the large intestine, may improve the absorption of minerals, helps with fat metabolism, and may assist in the treatment and prevention of obesity. [6] [7]
For more information on fiber supplements, see the prebiotics note.
DISCLAIMER: Before starting any supplement or medication, always consult with your healthcare provider to ensure it is a good fit for your child. Dosage can vary based on age, weight, gender, and current diet.
Fiber & Autism in the Research
Fiber Intake in Children
There is extensive research on dietary fiber and its effect on chronic diseases in adults, but very little research in children. [8]
Nine out of ten children do not meet their recommended fiber intake. The majority of fiber obtained in a child’s diet is from foods low in fiber. [8-9]
Fiber and Cognition
One study examined children aged between 7 and 9 and their dietary fiber intake on cognitive control. Results showed that the children who ate more fiber than their peers had better cognitive control and performance. [9]
Constipation
Prebiotic dietary water-soluble fiber isolated from partially hydrolyzed guar gum helped improve constipation and balance the gut microbiota in children with autism. [10]
Many studies have suggested that fiber contributes to the maintenance of the GI tract and its function, as well as the prevention and treatment of childhood constipation. [8]
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[1] Blake JS, Munoz K, Volpe S. Nutrition: From Science to You. 3rd ed. Pearson; 2016.
[2] Korczak R, Kamil A, Fleige L, Donovan SM, Slavin JL. Dietary fiber and digestive health in children. Nutr Rev. 2017;75(4):241-259. R, Kamil A, Fleige L, Donovan SM, Slavin JL. Dietary fiber and digestive health in children. Nutr Rev. 2017;75(4):241-259.
[3] Dietary Reference Intakes for Energy, Carbohydrate. Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2002/2005). This report may be accessed via www.nap.edu.
[4] Ma W, Nguyen LH, Song M, et al. Intake of Dietary Fiber, Fruits, and Vegetables and Risk of Diverticulitis. Am J Gastroenterol. 2019;114(9):1531-1538.
[5] Jalanka J, Major G, Murray K, et al. The Effect of Psyllium Husk on Intestinal Microbiota in Constipated Patients and Healthy Controls. Int J Mol Sci. 2019;20(2)
[6] Lattimer JM, Haub MD. Effects of dietary fiber and its components on metabolic health. Nutrients. 2010;2(12):1266-89.
[7] Ahmed W, Rashid S. Functional and therapeutic potential of inulin: A comprehensive review. Crit Rev Food Sci Nutr. 2019;59(1):1-13.
[8] Kranz S, Brauchla M, Slavin JL, Miller KB. What do we know about dietary fiber intake in children and health? The effects of fiber intake on constipation, obesity, and diabetes in children. Adv Nutr. 2012;3(1):47-53.
[9] Khan NA, Raine LB, Drollette ES, Scudder MR, Kramer AF, Hillman CH. Dietary fiber is positively associated with cognitive control among prepubertal children. J Nutr. 2015;145(1):143-9.
[10] Inoue R, Sakaue Y, Kawada Y, et al. Dietary supplementation with partially hydrolyzed guar gum helps improve constipation and gut dysbiosis symptoms and behavioral irritability in children with autism spectrum disorder. J Clin Biochem Nutr. 2019;64(3):217-223.
