What Is “Dietary Fiber”(for Purposes of Nutrition Labeling)?

FDA has issued two notices for publication in the Federal Register:

  1. A Request for Scientific Data, Information, and Comments (comments due within 45-days of publication); and
  2. A notice of availability about a draft guidance (comments due within 60-days of publication), Draft Guidance for Industry: Scientific Evaluation of the Evidence on the Beneficial Physiological Effects of Isolated or Synthetic Non-digestible Carbohydrates Submitted as a Citizen Petition (21 CFR 10.30).

Each of these documents pertains to the isolated or synthetic, non-digestible carbohydrates that presently are, and prospectively may be, within the meaning of “dietary fiber” for purposes of Nutrition Facts and Supplement Facts labeling. FDA also has issued a Science Review of Isolated and Synthetic Non-Digestible Carbohydrates, as well as Questions and Answers for Industry on Dietary Fiber.

In its May 20, 2016, final rule, Food Labeling: Revision of the Nutrition and Supplement Facts Labels, FDA provided a nutrition labeling definition for the previously undefined term, “dietary fiber”:

Dietary fiber is defined as non-digestible soluble and insoluble carbohydrates (with 3 or more monomeric units), and lignin that are intrinsic and intact in plants; isolated or synthetic non-digestible carbohydrates (with 3 or more monomeric units) determined by FDA to have physiological effects that are beneficial to human health.

21 C.F.R. § 101.9(c)(6)(i). The definition includes all intrinsic and intact, soluble and insoluble fiber from fruits, vegetables, and grains. The definition goes on to include seven dietary fibers that FDA already has determined to have physiological effects that benefit human health:

The following isolated or synthetic non-digestible carbohydrate(s) have been determined by FDA to have physiological effects that are beneficial to human health and, therefore, shall be included in the calculation of the amount of dietary fiber: [beta]-glucan soluble fiber (as described in §101.81(c)(2)(ii)(A)), psyllium husk (as described in §101.81(c)(2)(ii)(A)(6)), cellulose, guar gum, pectin, locust bean gum, and hydroxypropylmethylcellulose.

Id.

Stakeholders may request, through submission of a Citizen Petition, that FDA determine additional isolated or synthetic, non-digestible carbohydrates to have physiological effects that are beneficial to human health and, therefore, that such substances be included within the regulatory definition of “dietary fiber.” The draft guidance document represents FDA’s current thinking regarding the type of scientific evidence on which it will rely, and the scientific evaluation process it plans to use in determining the strength of the evidence for the relationship between an isolated or synthetic, non-digestible carbohydrate that is added to food and a physiological effect that is beneficial to human health.

In this regard, the Request for Scientific Data, Information, and Comments notes that, in addition to the seven dietary fibers already listed in the regulation, FDA has conducted a scientific literature review of clinical studies associated with 26 additional isolated or synthetic, non-digestible carbohydrates that are not listed as a dietary fiber in § 101.9(c)(6)(i). These substances are:

  1. Gum Acacia
  2. Alginate
  3. Apple Fiber
  4. Bamboo Fiber
  5. Carboxymethylcellulose
  6. Corn Hull Fiber
  7. Cottonseed Fiber
  8. Galactooligosaccharides
  9. Inulin/Oligofructose/Synthetic Short Chain Fructooligosaccharides
  10. Karaya Gum
  11. Oat Hull Fiber
  12. Pea Fiber
  13. Polydextrose
  14. Potato Fibers
  15. Pullulan
  16. Rice Bran Fiber
  17. High Amylose Corn/Maize Starch (Resistant Starch 2)
  18. Retrograded Corn Starch (Resistant Starch 3)
  19. Resistant Wheat and Maize Starch (Resistant Starch 4)
  20. Soluble Corn Fiber
  21. Soy Fiber
  22. Sugar Beet Fiber
  23. Sugar Cane Fiber
  24. Wheat Fiber
  25. Xanthan Gum
  26. Xylooligosaccharides

FDA’s review of these substances reportedly is consistent with the factors it provides in the draft guidance, and the clinical studies that it identified for the substances is summarized in its “Evaluation of the Beneficial Physiological Effects of Isolated or Synthetic Non-Digestible Carbohydrates.”

FDA is seeking comments both on its draft guidance and on its initial appraisal of the 26 substances. With regard to the 26 substances, it invites stakeholders to submit additional scientific data, information, and comments regarding:

  • The physiological endpoints that it has addressed in the science review for each of the 26 non-digestible carbohydrates, and
  • Other beneficial physiological endpoints and the relevant scientific data for a particular fiber.

This regulatory undertaking is of clear relevance to purveyors of conventional foods and dietary supplements that contain dietary fiber from a variety of sources.

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