FDA’s Rules for Dietary Fiber Are “Unreasonably Restrictive,” Associations Say


In public comments released today in response to FDA’s recent draft guidance on dietary fiber, two industry associations told the agency that the agency’s criteria for what is considered a dietary fiber are too stringent.

Photo © iStockphoto.com/matka_Wariatka

In public comments released today in response to FDA’s recent draft guidance on dietary fiber, two industry associations told the agency that the agency’s criteria for what is considered a dietary fiber are too stringent. Both the Council for Responsible Nutrition (CRN; Washington, DC) and the Natural Products Association (NPA; Washington, DC) urged FDA to reconsider its approach to defining a dietary fiber.

FDA published its draft guidance on fiber last November, explaining what criteria the agency would use to determine whether or not an ingredient meets the agency’s new definition of a dietary fiber. This new definition came about in 2014 when the agency announced it was redesigning the U.S. nutrition facts label-and, along with that, finally establishing the country's first-ever official definition for fiber.

In its final rule for the nutrition facts label published in May 2016, the agency proposed that the definition of a dietary fiber should be an ingredient that falls under any of the following:


  • 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.


While this definition seems to classify fibers in fruits or vegetables or ingredients like whole grains as fiber, it’s less clear whether the agency will consider some of the more advanced fiber ingredients companies use these days, such as insoluble and soluble prebiotic fibers like inulin, as dietary fibers unless they, as the agency says, “have physiological effects that are beneficial to human health.”

As Nutritional Outlook reported last June, suppliers of soluble fibers spent much of last year petitioning FDA and providing human clinical data on how their ingredients have beneficial effects on the body, hoping that the agency will say that they can call their ingredients dietary fiber on the nutrition facts label. FDA has not yet stated whether or not it will grant these petitions.

In their comments sent to FDA on February 13, CRN and NPA criticized FDA’s criteria for defining an ingredient as a dietary fiber, in CRN's words calling them “unreasonably restrictive.”

Both associations worry that under FDA’s current guidelines, companies would need to invest in new and costly scientific studies in order to demonstrate their ingredients have physiological benefits per FDA’s standards, including benefits like lowering blood glucose and cholesterol levels, lowering blood pressure, improving laxation and bowel function, increasing mineral absorption in the intestinal tract, or supporting weight management by enhancing satiety, NPA said.

In his comments, NPA’s CEO and executive director Dan Fabricant, PhD, told FDA point blank that “any non-digestible carbohydrates are beneficial to the digestive tract by their very nature” and therefore companies should not have to “perform additional expensive, wasteful” studies to prove physiological benefits.

Fabricant explained: “The presence of non-digestible carbohydrates in the intestines will cause less water to be resorbed during transit through the large intestine. Whether carbohydrates are non-digestible in the human gut due to the types of chemical bonds they contain or due to lack of enzymes (i.e., carbohydrate intolerance in small children), any undigested carbohydrates will cause an osmotic load that attracts water and electrolytes into the bowel. Water will always move across semi-permeable barriers (intestinal wall) from an area of lower solutes to an area of higher solutes. This will result in food having a shorter transit time in the gastrointestinal tract, providing a beneficial laxative effect. Non-digestible carbohydrates [NDCs] do not need additional expensive studies to show a beneficial physiological effect. They demonstrate a benefit by their very nature of being non-digestible, promoting an osmotic and bulk laxative physiological effect."

CRN advised the agency not to take too stringent an approach when reviewing the scientific evidence that does exist. For instance, the association urged FDA to consider studies in both non-diseased subjects and diseased subjects (such as those with IBS) and also to consider unpublished studies. “FDA should consider the unique challenges in conducting and interpreting nutrition research,” wrote CRN’s Andrea Wong, PhD, vice president, scientific and regulatory affairs, and Haiuyen Nguyen, director, scientific and regulatory affairs, in their comments to FDA. “Dietary fiber does not exert effects in the body in isolation from the diet or host gut environment, and its effects manifest over many years, as is the case with all nutrients. Therefore, scientific evaluation of the beneficial physiological effects of dietary fiber should consider quality evidence from studies of both healthy and non-healthy populations and studies of isolated NDCs and NDCs in combination with other food components, among the totality of available evidence.”

CRN also said the agency should not disqualify studies that companies did prior to FDA’s new definition. “If FDA applies the evaluation criteria outlined in the draft guidance, decades of scientifically valid and important research would be inappropriately excluded from the body of evidence reviewed and therefore the number of well-researched NDCs that should be labeled as dietary fiber would be substantially reduced,” CRN wrote.

In addition to calling FDA’s criteria overly restrictive, NPA pointed out that the agency has not done an economic analysis to show how its new definition will burden food and supplement companies if they need to invest in new studies-or if they are no longer able to label their ingredients as fiber at all.

“Dietary fiber declarations in the food and supplement industries have a large footprint in the market and serves as a significantly declared label component in many common products,” Fabricant wrote. “NPA believes the number of unique conventional foods and dietary supplements selling non-digestible isolated or synthetic carbohydrates as dietary fiber is enough to warrant an [Office of Management and Budget] review based on its economic significance.”

Finally, CRN pointed out, if companies are not able to call their ingredients fibers, they might remove them from products on shelves and put out of touch a “shortfall nutrient” that many consumers already don’t get enough of and need more of to support good health.


Also read:

At IFT, Fiber Suppliers “Confident” FDA Will Define Their Ingredients as Dietary Fibers

The Case for Soluble Fiber

Will a New EU Health Claim for Chicory Root and Other Healthy Blood Sugar Ingredients Win New Customers?


Jennifer Grebow
Nutritional Outlook magazine

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