Quest Nutrition misleadingly promotes its products as healthy, a new class action lawsuit alleges.

On Sept. 23, 2026, Sue Colby filed a class action lawsuit against Quest Nutrition LLC in the U.S. District Court for the Central District of California.

The lawsuit claims Quest sells its protein bars, cookies, candy and baked goods as healthy foods while sweetening them with erythritol, a sugar alcohol researchers reportedly linked to heart attack and stroke risk.

The marketing at issue

Quest, a subsidiary of Simply Good Foods, markets its snacks as high in protein and low in sugar, and its packaging promises "only quality ingredients," according to the complaint. Retailers stock the products in nutrition and sports-nutrition aisles and at supplement chains such as GNC and The Vitamin Shoppe, which the lawsuit says reinforces their image as health foods.

The proposed class action reportedly covers at least 45 products:


  • Protein bars (28 flavors)

  • Cookies (six regular and four frosted products)

  • Bake shop items (four products, including donuts, brownies and muffins)

  • Candy (three products)

The research behind the lawsuit

The filing claims food companies add erythritol in gram-level amounts far beyond the traces found naturally in fruit. The lawsuit relies most heavily on a 2023 Cleveland Clinic study in Nature Medicine that reportedly found participants with elevated blood erythritol levels were roughly twice as likely to suffer a heart attack, stroke or death within three years.

The same researchers allegedly found that a single erythritol-sweetened drink raised blood levels more than 1,000-fold within minutes, keeping them high enough to affect platelet function for at least 48 hours, according to the proposed class action. A 2024 follow-up study reportedly found erythritol, unlike glucose, made platelets in healthy volunteers more reactive, and its authors called for discussion of whether to ban the sweetener, the complaint claims.

A 2025 University of Colorado Boulder study allegedly found erythritol-impaired cells lining the brain's small blood vessels, which the lawsuit ties to stroke risk.

Colby says she bought a Quest chocolate chip cookie dough protein bar after reading the brand's ingredient quality and mission claims. She paid a premium over other protein bars and claims she would have skipped the purchase or paid less had she known those claims were misleading, the complaint alleges.

The legal claims

The complaint brings four claims:


  • California Consumers Legal Remedies Act, which bars misrepresenting a product's characteristics, benefits or quality

  • California Unfair Competition Law, which prohibits unlawful, unfair and fraudulent business practices

  • California False Advertising Law, which prohibits untrue or misleading advertising

  • Unjust enrichment, which applies when a company profits unfairly at someone else's expense

Colby seeks compensatory, statutory and punitive damages, restitution, attorneys' fees and a court order requiring Quest to stop the challenged marketing and correct the public's impression of its products.

What the Quest Nutrition lawsuit means for buyers

Colby seeks to represent a nationwide class of people who bought the listed Quest products for personal use plus a California subclass. The three California law claims cover only the subclass, while the unjust enrichment claim includes buyers nationwide.

If Quest does not correct the alleged violations within 30 days of a pre-suit notice her attorneys mailed, the lawsuit says Colby plans to seek additional damages under the Consumers Legal Remedies Act.

As of this writing, there is no settlement, no claims process and no money available.