On February 28, 2018, FDA issued final guidance on Food Labeling: Scientific Evaluation of the Evidence on the Beneficial Physiological Effects of Isolated or Synthetic Non-Digestible Carbohydrates Submitted as a Citizen Petition. This Guidance explains FDA’s approach to reviewing scientific evidence in determining whether an isolated or synthetic non-digestible carbohydrate added to food has a physiological effect that is beneficial to human health and thus qualifies as “dietary fiber.”

Before 2016, FDA regulations did not define the term “dietary fiber.” In May 2016, FDA adopted a definition of “dietary fiber” for food labelling purposes that includes (1) non-digestible carbohydrates that are intrinsic and intact in plants and (2) isolated or synthetic non-digestible carbohydrates determined by FDA to have physiological effects that are beneficial to human health. Fiber-containing foods (like fruits and vegetables) are known to provide health benefits, but the physiological effects of isolated or synthetic non-digestible carbohydrates from other sources must be determined by evaluating such carbohydrates individually. Only non-digestible carbohydrates specified in FDA’s regulation may be listed as “dietary fiber” on a food label. But any interested person may request by citizen petition that FDA’s regulation to be amended and this Guidance describes the process FDA will follow when considering such requests.

FDA will perform three steps when evaluating whether an isolated or synthetic non-digestible carbohydrate has beneficial physiological effects: (1) assess publicly available scientific studies; (2) eliminate the studies from which scientific conclusions cannot be drawn; and (3) evaluate the overall strength of the scientific evidence. Regarding the first step, FDA indicates that it will primarily rely on human intervention studies, noting that FDA considers intervention studies superior to observational studies, research synthesis studies, and animal or in vitro studies, all of which have flaws that prevent scientific conclusions from being drawn from them. Next, FDA will evaluate each human intervention study individually to determine whether it is possible to draw scientific conclusions from it, considering factors such as the study design, measurement of end points, controls, length of evaluation, statistical analysis, and location. Lastly, FDA will consider the overall strength of the scientific evidence, looking at the number of studies, doses provided, types of food used, outcomes, consistency of findings, and relevance to the U.S. population.