FDA Acts on Dietary Fiber: Issues Draft Guidance and Report of Evidence for Twenty Six Isolated and Synthetic Non-digestible Fibers

By Riëtte van Laack –

As we previously reported, in May 2016, FDA published a final rule amending the nutrition labeling regulations. Among other things, FDA defined dietary fiber as non-digestible soluble and insoluble carbohydrates (with three or more monomeric units), and lignin that are intrinsic and intact in plants and isolated or synthetic non-digestible carbohydrates (with three or more monomeric units) that FDA determines to have a physiological effect that is beneficial to human health. The final rule identified only 7 isolated or synthetic fibers that would meet the definition of dietary fiber.  FDA indicated that there was insufficient evidence of a beneficial physiologic effect for more than twenty additional non-digestible carbohydrates, and that the Agency would issue a document summarizing that evidence.  In addition, FDA announced that it would issue guidance regarding the type of evidence and the scientific evaluation process the Agency would (and presumably did) use in determining the strength of the evidence for the relationship between an isolated or synthetic non-digestible carbohydrate and a physiological effect that is beneficial to human health.  On November 22, FDA announced the availability of both the report and the draft guidance.

In its report, FDA summarizes the results of the Agency’s scientific review of the evidence for beneficial physiological effects of 26 non-digestible carbohydrates: Gum Acacia; Alginate; Apple Fiber; Bamboo Fiber; Carboxymethylcellulose; Corn Hull Fiber; Cottonseed Fiber; Galactooligosaccharides; Inulin/Oligofructose/Synthetic Short Chain Fructooligosaccharides; Karaya Gum; Oat Hull Fiber; Pea Fiber; Polydextrose; Potato Fibers; Pullulan; Rice Bran Fiber; High Amylose Corn/Maize Starch (Resistant Starch 2); Retrograded Corn Starch (Resistant Starch 3); Resistant Wheat and Maize Starch (Resistant Starch 4); Soluble Corn Fiber; Soy Fiber; Sugar Beet Fiber; Sugar Cane Fiber; Wheat Fiber; Xanthan Gum; Xylooligosaccharides. As with the memorandum in which FDA described the isolated dietary fibers included in the final rule, the report provides brief summaries of each study that meets FDA’s criteria and lists studies that were not considered because they did not meet all criteria for inclusion (e.g., the study did not include a control group, or was in a foreign language). However, there is no final conclusion or comment regarding the strength of the evidence for any of the 26 fibers. 

Since the publication of the final rule, FDA has received several citizen petitions to amend the definition of dietary fiber by including additional non-digestible carbohydrates. Other than a footnote referencing the citizen petition for soluble corn fiber, FDA does not mention these citizen petitions and it is not clear whether FDA considered any non-public information provided in those citizen petitions in its review.

FDA asserts that its review is consistent with the approach laid out in the draft guidance, which the Agency issued on the same day. The approach laid out in the draft guidance appears similar to the approach described in the 2009 guidance for evaluation of health claims.

In addition to the draft guidance and the report, FDA published Questions and Answers for Industry on Dietary Fiber.

FDA invites additional scientific data and information and comments regarding the physiological endpoints that the Agency addressed in the review of scientific evidence for each of the 26 non-digestible carbohydrates, and possible other beneficial physiological endpoints, e.g., blood pressure and the data for any of these or other non-digestible carbohydrates.

Comments regarding FDA’s review of the 26 isolated and synthetic non-digestible carbohydrates are due January 9, 2017.  Comments regarding FDA’s draft guidance are due January 23, 2017.