Issue 5 (October 19, 2026)

After my posts on class action challenges to “no sugar” claims on products that contain allulose, I thought I’d explore other Franco-esque vulnerabilities. I did not find many.

But fiber caught my attention in part because fiber claims have become as ubiquitous as protein claims on food and beverage products. And perhaps our understanding of fiber is as incomplete as our understanding of protein. While not all proteins are absorbed at the same rate into the body, not all fibers perform the function we think they do.

FDA has exercised its enforcement discretion with respect to counting some “isolated or synthetic non-digestible carbohydrates” as dietary fibers, provided that they have a beneficial effect. But this is a different scenario than Franco. In Franco, FDA announced that it would permit (via enforcement discretion) manufacturers to omit allulose from total and added sugar declarations; and in the course of litigation, FDA confirmed that allulose is, in fact, a sugar. Here, FDA announced that certain synthetic carbohydrates could be listed as dietary fibers so long as they have a beneficial physiological effect, including effects that are unrelated to digestion. On the surface, then, the exercise of enforcement discretion appears to be aligned with FDA policy goals, unlike the case with allulose.

Still, the beneficial effects that consumers expect from dietary fiber are only a subset of the beneficial effects that can qualify a synthetic carbohydrate as dietary fiber. Most consumers see “fiber” and think “digestive health.” But FDA’s non-exhaustive list of benefits for synthetic fibers include such things as mineral absorption and lowering cholesterol. In other words, consumers expect one benefit from dietary fiber, yet FDA credits synthetic carbohydrates when it confers any physiological health benefit.

Does this mean that dietary fiber is the next seam for class action plaintiffs to mine? I don’t think so, except in certain narrow cases. And even then, the exposure would arise from poor claim substantiation, not from a Franco theory of recovery. Federal preemption likely protects manufacturers who follow the regulations when they make “good source of fiber” claims or gram-or DV-based claims (Franco does not create the gap here that it does with allulose). Express preemption, however, does not reach structure-function claims on conventional foods. When manufacturers move beyond “good source” claims into statements about what the fiber does and the fiber in the product is not the type that delivers that benefit, they face exposure under state laws that mirror the FDCA’s general ban on false or misleading advertising.

This piece looks at that gap: what dietary fiber is as a legal matter, what consumers think it is, and what a "good source" claim means when the grams come from one kind of fiber rather than another.

FDA's definition is functional, not intuitive. Dietary fiber is "non-digestible soluble and insoluble carbohydrates (with 3 or more monomeric units), and lignin that are intrinsic and intact in plants" plus "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) (“Added Dietary Fiber”) (the labels “Intrinsic” and “Added” Dietary Fiber are mine, not FDA’s). Intrinsic Dietary Fiber includes the fiber in an apple or a bowl of oatmeal. Added Dietary Fiber includes ingredients that are either (i) isolated from a natural source, such as plants or seaweed, or (ii) synthesized, provided that they confer a beneficial physiological effect.

The regulation currently names seven isolated or synthetic fibers that meet that test: (i) beta-glucan soluble fiber; (ii) psyllium husk; (iii) cellulose; (iv) guar gum; (v) pectin; (vi) locust bean gum, and (vii) hydroxypropyl-methylcellulose. In June 2018, FDA announced that it would exercise enforcement discretion for eight more: (i) mixed plant cell wall fibers; (ii) arabinoxylan; (iii) alginate; (iv) inulin and inulin-type fructans; (v) high amylose starch (resistant starch 2); (vi) galactooligosaccharide; (vii) polydextrose; and (viii) resistant maltodextrin/dextrin. (If you were reading the last two sentences out loud: I’m sorry.) FDA has since granted petitions extending the same discretion treatment to cross-linked phosphorylated RS4, glucomannan, and acacia (gum arabic), bringing the total to eleven. FDA’s announcement meant that manufacturers could count these fibers as dietary fiber while FDA works on a rule to formally add them to the regulation.

The legal test for an added fiber to be a dietary fiber, then, is whether it has a beneficial physiological effect. FDA's non-exclusive list of effects includes lowering blood glucose, lowering cholesterol, lowering blood pressure, increasing the frequency of bowel movements, increasing mineral absorption, and reducing energy intake. (Preamble to 2016 final rule). One of these is enough. A fiber cleared for helping the body absorb calcium is just as much "dietary fiber" on the Nutrition Facts panel as one cleared for regularity. The panel shows a single number for total dietary fiber. Soluble and insoluble fiber may be listed separately on a voluntary basis, and each must be listed when the label makes a claim about it. 21 C.F.R. § 101.9(c)(6)(i)(A)–(B).

That single number (grams or percentage) can obscure what function the fiber performs. Of the isolated fibers, inulin and resistant maltodextrin were cleared for calcium absorption, polydextrose for reduced energy intake, and several others for lowering post-meal blood glucose (FDA science review). None of the eleven fibers now covered by enforcement discretion was cleared for regularity.

Consumers do not read fiber that way. In a large 2021 survey of 42,018 U.S. grocery shoppers, the most commonly cited benefit of fiber was improving bowel movements, chosen by 64.4 percent of respondents. Second was "supporting healthy gut bacteria," at 52.4 percent, which is not among the six effects FDA lists (though FDA describes its list as non-exclusive). Every other FDA-recognized benefit was identified by fewer than 40 percent. Reduced energy intake was identified by 4.7 percent, fewer than the 11.5 percent who picked the made-up option of improving skin complexion. On average, respondents identified 1.77 of FDA's six recognized benefits, and only 2.3 percent identified all six.

Belief also drives behavior. Respondents who recognized more benefits were much more likely to consider fiber when choosing food. Compared with people who recognized none, the odds rose from about three times as likely for one benefit to 14.3 times for all six. Adding the gut-bacteria belief pushed the top figure above 24 times. (Note that the study measured what people said they consider, not what they bought, and the sample skewed female and older.)

A February 2026 survey from the International Food Information Council points the same way. Seven in ten Americans believe fiber and/or whole grains are good for their health. Among the top reasons they give for eating fiber is to support gut health. They are also more likely to look for claims on the front of the package than to read the Nutrition Facts panel. About 28 percent look for "good/excellent source of fiber" statements, while 17 percent check the Dietary Fiber line.

Together, these studies suggest that consumers tend to read "fiber" as shorthand for regularity and gut health. Consumers form their impression from the front of the package and rarely check the nutrition fact panel or ingredient line for more information that might complicate their impression. The regulation treats fiber as a category of carbohydrates, each with its own documented effect. The shopper treats it as one nutrient with one familiar job.

The nutrient content claims sharpen the problem. A food may claim to be a "good source," or say it "contains" or "provides" fiber, if it has 10 to 19 percent of the Daily Value per reference amount customarily consumed. "High," "rich in," or "excellent source of" requires 20 percent or more. 21 C.F.R. § 101.54(b)-(c). With a Daily Value of 28 grams, that means about 2.8 to 5.5 grams per serving for “good source” and 5.6 or more for “high.” 21 C.F.R. § 101.9(c)(9). If the food is not “low fat,” any fiber claim must be accompanied by a disclosure of total fat per serving. 21 C.F.R. §§ 101.54(d)(1), 101.62(b)(2). Implied claims count too: under FDA's rules, saying a food is "high in oat bran" implies that the food is high in dietary fiber.

None of these rules asks which fiber supplies the grams. A "good source" claim is satisfied by any combination of qualifying fibers that adds up to the threshold. Picture a snack bar that reaches 15 percent of the Daily Value from a little oat bran, a larger dose of inulin, and some soluble corn fiber or polydextrose to round out the texture. The claim is accurate. But the grams do not all do the same thing:

A consumer who reads "good source of fiber" as "this will help with regularity" is drawing a conclusion that the product may not support, even though the claim itself is lawful.

Blends raise a second question about the arithmetic. Manufacturers that mix qualifying fiber with non-digestible carbohydrates that do not meet the definition must keep records showing how much of the non-qualifying material was added. 21 C.F.R. § 101.9(g)(10). Some products reach the threshold only because the enforcement-discretion fibers are counted. For those, the claim depends on FDA's stated intention to amend the rule rather than on the codified list. The better reading is that the regulation and FDA’s position still align. The definition requires a fiber to be “determined by FDA” to be beneficial, and FDA has made that determination for each of these fibers. But the determinations live in guidance and petition responses, not in the codified list. A plaintiff could argue, as in Franco, that guidance is not the regulation.

The deeper point is that "good source of fiber" is a claim about quantity, and consumers read it as a claim about function. With a single traditional food, the two roughly line up: an apple's fiber is an apple's fiber. With an engineered blend, they can come apart. Nothing in the nutrient content rules requires the manufacturer to explain that gap.

My earlier newsletter covered the Seventh Circuit's decision in Franco v. Chobani. There, the court held that FDA's enforcement-discretion guidance on allulose did not change the sugar regulation, so a state-law claim that paralleled the regualtion as written was not preempted. Fiber looks similar on the surface, because many fiber declarations rest on enforcement discretion. The cases are distinguishable, though. FDA's allulose policy cut against the sugar regulation. Its fiber policy is consistent with the fiber regulation, because FDA has made the benefit finding the definition requires. I think a Franco-style challenge to a fiber declaration is less likely to succeed, but the argument isn’t foreclosed.

The more realistic exposure comes from benefit statements. A "high fiber" or "good source of fiber" claim that meets the regulatory threshold is a defined nutrient content claim under 21 U.S.C. § 343(r) and 21 C.F.R. § 101.54. A state-law theory that a compliant claim is misleading should run into express preemption under 21 U.S.C. § 343-1(a)(5), which bars state requirements for these claims that are not identical to federal law. Benefit statements are different:

The structure-function statements, and any health claim that doesn't meet its federal conditions, are therefore where the exposure lies. A state-law claim that a structure-function statement is misleading tracks § 343(a), which § 343-1(a) does not preempt. Because the FDCA has no private right of action (21 U.S.C. § 337(a)), plaintiffs bring these claims under state consumer-protection statutes, such as the Illinois Consumer Fraud Act or California's UCL. They must frame them as state-law claims that parallel the federal standard, not as attempts to enforce the FDCA itself. If the fiber in the product doesn't deliver the benefit the label claims, those statements are vulnerable to a putative class action.

Fiber is one of the few nutrients where the legal definition, the science, and consumer understanding have drifted apart. The regulation asks whether an ingredient has a benefit. The consumer tends to assume it has the benefit, most likely regularity or gut health. And the nutrient content claim measures grams without regard to which benefit those grams deliver.

Practical Implications:

A plain "good source of fiber," with no benefit attached and an accurate gram count, remains the lowest-risk position. The moment the label tells consumers what the fiber does, counsel should be able to point to the specific fiber, and the specific finding, that backs it up.

#foodlaw #CPG #OutsideGC

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