Allulose is a structural variant of fructose. It has the same chemical components, linked together in the same way, but the three-dimensional structure is different. In biological systems, shape matters. However, in the world of regulation and law, where words and categories matter, this nuance and its downstream effects are ignored. That difference lies at the root of a raft of lawsuits over the meaning of “sugar-free” and offers several lessons that may benefit an informed consumer, like yourself.
Allulose
Allulose is a naturally occurring sugar created by enzymatic modification of fructose. Before its commercial introduction, it was estimated that we might consume roughly 95 mg/day, primarily from dried fruits such as figs and raisins, fruit juices, and “ingredients” like maple syrup or molasses. In 1994, scientists identified the enzymes that convert fructose to allulose, enabling large-scale commercial production from corn.
The FDA has approved allulose as Generally Recognized as Safe (GRAS) on three separate occasions, in 2011, 2014, and 2017, for use as a sugar substitute in “low-calorie” foods. Human studies have not identified any significant toxicologic effects, and the “practical” upper limit on human consumption is constrained by transient bloating and GI discomfort associated with poorly digestible carbohydrates. [1] It seems the maximum allulose we can tolerate is roughly 45 grams/day. That limit was pushed higher in animal studies in rats, where allulose constituted 3% of their total diet for 12 to 18 months, and no adverse toxicological effects were identified. Scaling that to humans, with greater uncertainty, suggests we might tolerate even double the already established human limits.
While allulose has roughly 70% of the sweetness we attribute to sucrose, its physiological behavior is quite different. The portion absorbed through the small intestine is primarily excreted unchanged in our urine. That means allulose delivers about 0.2 to 0.4 calories per gram, compared with the standardized 4 calories for carbohydrates. The rest passes to our colonic microbiome, where it is converted into short-chain fatty acids, generally considered a positive nutritional feature but also the underlying cause of the aforementioned bloating.
Allulose’s impact on carbohydrate metabolism is quite different than what we would anticipate for a sugar. In animal models, allulose consumption was associated with improved glucose tolerance and insulin sensitivity. In human studies, the effect “pointed” in the same direction but was less pronounced.
Metaphorically speaking, while it looks like a duck, it does not walk like one. That distinction between categorization and physiology led the FDA to issue guidance on the labeling of allulose in our foods.
Squaring the Circle
In 2020, the FDA, in an effort to align categorization with physiology, issued guidance to manufacturers on how to correctly label allulose.
- Calories – while existing regulation would require allulose to be counted at 4 calories per gram, like other carbohydrates, the FDA set the calorie estimate at 0.4 calories per gram, in line with allulose’s physiologic action.
- Total Carbohydrate – once a carb, always a carb. Despite allulose’s minimal impact on blood glucose and its lower caloric contribution, the FDA rejected replacing a chemical classification with a physiologic one.
- Total Sugars – by regulatory definition, total sugars include monosaccharides such as allulose. However, the FDA recognized that newer sugars challenge a definition based solely on chemistry. Total sugars are listed on food labels “to assist consumers in maintaining healthy dietary practices.” Because allulose does not cause dental caries (cavities) and has negligible glycemic responses, the FDA did not require allulose to be included in the count of total sugars.
- Added Sugars – allulose was not required here because added sugars are a subset of Total Sugars, and the FDA applied the same reasoning.
The regulatory wrinkle in all of this is that the FDA solved the squaring of the circle between category and physiology not by providing a definitional answer but by “enforcement discretion.” Redefining categories is hard work, especially when building consensus among nutrition stakeholders who bring strong opinions and less-certain science to the table. The guidance repeatedly references the FDA’s current thinking, which it will reconsider in “future rulemaking,” effectively kicking the hard work down the road. Enforcement discretion is immediate and non-binding, but inherently uncertain.
Enforcement discretion allowed labels to reflect what allulose does rather than simply what its chemistry says it is. But discretion is not regulation, and the gap between them has allowed the plaintiff’s bar to walk across it and bring class-action lawsuits.
When Guidance Meets the Law
The 2020 FDA guidance dealt with how allulose appears on the Nutrition Facts panel. In addition to not redefining categories, the FDA did not rewrite the separate rules governing claims such as “zero sugar.” While enforcement discretion may allow manufacturers to omit allulose from the sugar line, a claim of “zero sugar” violates the regulatory definition still in effect
In Franco v. Chobani, Jason and Abigail Franco contend that Chobani’s “Zero Sugar Yogurt” contains 4 grams of allulose, a sugar, making the labeling deceptive. The initial litigation raised questions about federal preemption of state regulations, leading to the case’s dismissal. The Seventh Circuit reversed, reinstating the suit. The court noted that allulose remains legally a sugar under existing regulations, irrespective of the FDA’s regulatory guidance and enforcement discretion. The case is now proceeding without a determination of whether consumers were deceived or whether Chobani was liable.
Franco has become a template, and additional cases have been filed against Liquid Death, WK Kellogg, and KIND, all exploiting the same gap between allulose’s physiologic treatment under FDA guidance and its formal status under unrevised regulation. While FDA enforcement may have changed, the courts are applying the definition, not the discretion.
The FDA accommodated the science, recognizing the physiologic exception but left the legal categorization intact. The result is to shift the determinations from the regulator to the court.
Science Enters the Courtroom
Moving a scientific question from a regulatory agency to the court changes who decides and how decisions are made. The FDA's task is to integrate our current scientific knowledge and determine which conclusions best reflect the available evidence. The FDA process accommodates uncertainty and heterogeneous evidence that the courts do not. Moreover, the FDA makes policy judgments about how much evidence is sufficient to protect consumers. That is not the court's role.
The court's task is to determine what the law says and apply it to the particular dispute before it. The court interprets legal texts, using the tools of legal interpretation as embodied in evidentiary law, e.g., the Daubert Decision [2]. The Supreme Court’s decision in Loper Bright is clear. Congress may delegate policymaking to regulatory agencies, but interpreting statutory language remains a judicial function.
The Cost of a Regulatory Shortcut
Enforcement discretion served as a regulatory hack, an expedient providing the desired practical outcome without undertaking the more arduous task of rulemaking. It worked for the FDA and manufacturers until they entered the court, and the shortcut has now come back to bite them both.
Had the FDA completed its task, redefining carbohydrates or granting an exemption for allulose based on its distinct physiologic behavior, Franco might still have raised questions about deceptive marketing, but the peculiar dispute over whether something the FDA says need not be counted as sugar is nevertheless legally a “sugar” would largely disappear.
That is the larger lesson of allulose. Enforcement discretion is useful precisely because it is faster and easier than rulemaking, but it cannot substitute indefinitely for it. When scientific understanding outgrows a regulatory definition, an agency eventually has to reconcile the two. Otherwise, the unresolved contradiction does not disappear; it simply moves somewhere else.
In this case, it moved to court. Judges can interpret and apply the rules the government has written, but they cannot finish the scientific and regulatory work the FDA chose to leave undone. Franco and the lawsuits following it are the predictable cost of regulating by workaround — and a reminder that we should expect regulatory agencies not merely to acknowledge when their rules no longer fit the science, but to fix them.
[1] Poorly digested (absorbed) carbohydrates in the small intestine pass into the large intestine, where our microbiome happily ferments them, producing gases that we experience as bloating.
[2] Daubert is the legal standard federal judges use to determine whether scientific expert testimony is sufficiently reliable and relevant to be presented in court. Rather than requiring scientific consensus, judges consider factors that make the testimony generally accepted within the relevant scientific community.
Chuck Dinerstein, MD, MBA
Director of Medicine
Dr. Charles Dinerstein, M.D., MBA, FACS is Director of Medicine at the American Council on Science and Health. He has over 25 years of experience as a vascular surgeon.
