Quest Nutrition, maker of Quest Bars and other high-protein products, has been the subject of several class action lawsuits since 2013. The best-known Quest Bar lawsuit challenged the company’s fiber labeling and settled in 2014, but Quest has since faced additional suits over misleading “white chocolate” marketing, erythritol disclosures, and, most recently, lead levels in its protein shakes.
The 2013 Fiber Class Action
The original Quest Bar lawsuit, David Takeda v. Quest Nutrition, LLC, and General Nutrition Centers, Inc. (Case No. 2:13-cv-6656), was filed in the U.S. District Court for the Central District of California. The plaintiff alleged that Quest Bars understated their calorie counts by at least 20 percent and overstated their dietary fiber content by more than 750 percent because the bars relied on isomalto-oligosaccharides (IMOs) as a fiber source.1PricePlow. Isomaltooligosaccharide
The parties filed a notice of settlement on October 6, 2014, indicating they had reached an agreement and would file a stipulated dismissal with prejudice as to the plaintiff.2PricePlow. Quest Bar IMO Fiber Lawsuit Settlement Notice The specific settlement terms were not made public.
Why IMOs Were the Problem
Although IMOs were marketed as a fiber, research showed they are substantially broken down by enzymes in the small intestine rather than passing through undigested. Studies estimated IMOs deliver roughly 70 to 80 percent of the digestible energy found in sugar and can produce blood glucose and insulin responses comparable to glucose itself.3Alex Leaf. Isomalto-Oligosaccharides Are Not a Fiber A 2022 paper in Food Chemistry concluded that IMOs should be reclassified as “slowly digestible carbohydrates” rather than dietary fibers.4ScienceDirect. Isomalto-Oligosaccharides Reclassification Study
The FDA reached the same conclusion. After reviewing a citizen petition from IMO manufacturer BioNeutra, the agency declined to add IMOs to its official list of non-digestible carbohydrates that qualify as dietary fiber on nutrition labels.3Alex Leaf. Isomalto-Oligosaccharides Are Not a Fiber
Reformulation
Quest eventually switched away from IMOs. The company said it had heard reports that “IMO fiber, depending on the type, could change its chemical composition from a fiber to a carbohydrate” in some people and moved to soluble corn fiber, which it described as “far superior” though more expensive.5Muscle & Fitness. A Closer Look at the Ingredients in Your Quest Bars The transition was confirmed by mid-2016.6PricePlow. Quest Bars Soluble Corn Fiber Unlike IMOs, soluble corn fiber is among the isolated fibers the FDA recognizes as qualifying for the dietary fiber declaration.7Regulations.gov. Top Health Ingredients Citizen Petition for IMO Dietary Fiber Classification
The 2020 White Chocolate Lawsuit
In July 2020, a separate class action was filed in the U.S. District Court for the Southern District of New York. In Jenny Jolly v. Quest Nutrition LLC (Case No. 7:20-cv-05125), the plaintiff alleged that Quest’s “White Chocolate Raspberry” protein bars were misleadingly marketed as containing white chocolate when the product did not meet the legal definition of white chocolate, which requires specific dairy ingredients and nutritive carbohydrate sweeteners.8Top Class Actions. Quest Nutrition Class Action Lawsuit Claims Protein Bars Have No White Chocolate
The complaint, brought by attorney Spencer Sheehan, asserted claims under New York consumer protection law, the Magnuson-Moss Warranty Act, and common law theories including fraud and unjust enrichment.9ClassAction.org. Jolly v. Quest Nutrition LLC Complaint No public updates on the outcome have been reported as of 2026.
The 2026 Lead Content Lawsuit
The most recent lawsuit against Quest was filed on March 11, 2026. In Tinamarie Barrales v. Quest Nutrition, LLC (Case No. 26STCV07966), filed in the Superior Court of California, County of Los Angeles, the plaintiff alleges that several Quest protein drinks contain lead at levels exceeding California’s Proposition 65 threshold without the required safety warnings.10ClaimDepot. Quest Nutrition Lawsuit Claims Protein Shakes Contain Lead Above Limit
The complaint targets seven ready-to-drink products: Quest Protein Shakes in vanilla, chocolate, salted caramel, and coffee, and Quest Protein Milkshakes in vanilla, chocolate, and strawberry. Independent laboratory testing conducted in November 2025 reportedly found that daily consumption of a single bottle of the vanilla protein shake would result in lead exposure of 0.65 micrograms, or 130 percent of the state’s maximum allowable dose level of 0.5 micrograms per day. The vanilla milkshake tested at 2.9 micrograms per day, or 580 percent of the allowable limit.10ClaimDepot. Quest Nutrition Lawsuit Claims Protein Shakes Contain Lead Above Limit
The lawsuit seeks an injunction requiring compliant warning labels, consumer restitution, disgorgement of profits, civil penalties, and a product recall. The case remains pending as of mid-2026, and the allegations have not been proven in court.
The Erythritol Class Action
Quest also faces class action litigation as of 2026 involving erythritol, a sugar alcohol used in some of its products. The claims fall within a broader wave of “health and safety disclosure” lawsuits, in which plaintiffs argue that companies market products as healthy while allegedly omitting material information about potential cardiovascular risks associated with erythritol.11Juris Law Group. Class Actions Newsletter Food and Beverage May 2026 Specific details about the case, including the plaintiff’s name, case number, and court, have not been publicly reported.