UC Davis 2026 Follow-Up Study Finds Avocado Oil Adulteration Spreads to Chips, Mayonnaise and Dressings
A 2026 UC Davis follow-up study confirms that avocado oil adulteration has moved into processed foods such as chips, mayonnaise and salad dressings. The study found 93% of chips labeled '100% pure avocado oil' were adulterated, along with 71% of mayonnaise (100% for U.S.-made samples) and 100% of salad dressings. Adams Group, whose Marianne's brand was used as a purity benchmark, highlights the need for rigorous testing and supply chain transparency.
SACRAMENTO, Calif. — Six years after a UC Davis study revealed that 82% of avocado oil sold in the U.S. was rancid or mixed with cheaper seed oils, a new 2026 follow-up study shows the problem has not abated—it has expanded. Adulteration is now widespread in the fast-growing "Made with Avocado Oil" categories, including chips, mayonnaise and salad dressings.
The economics help explain the persistence of fraud. Pure conventional avocado oil costs $4–5 per pound, while seed oils cost between $0.50 and $1.50 per pound. The premium on the label is real, but the oil inside often is not.
"A purity claim is only as good as the supplier behind it. Purity isn't a single test — it's a system. One that starts at the source, runs through every step of refining, and lives in the lot-level documentation behind every delivery. The brands that build it right in the next twelve months will own the category. The ones that don't will be the next headline." — Wayne Adams, CEO, Adams Group
Adams Group's retail brand, Marianne's avocado oil, was one of only two brands that tested 100% pure in the UC Davis 2020 research. In the 2026 study, Marianne's avocado oil was used as the benchmark for purity.
2026 UC Davis Study Findings
The findings from the 2026 UC Davis study are stark: 93% of chips labeled "100% pure avocado oil" were found to be adulterated. Mayonnaise fared no better—71% failed the same promise, but when looking specifically at U.S.-made data, that number climbs to 100%. Salad dressings were 100% adulterated across the board.
Consumers paying a premium for a cleaner oil are being misled at nearly every turn, and the brands responsible have continued making claims they cannot back up. The study makes one thing clear: in a category full of false promises, the label cannot be trusted.
Adams Group's Approach to Purity
Adams Group defines purity differently from the rest of the industry. As one of the only avocado oil refineries in the U.S., Adams Group controls the full processing chain from crude intake through finished ingredient delivery. Every incoming load undergoes authenticity testing before refining begins.
Bulk avocado oil costs up to five times more than seed oils, making adulteration a common and calculated business decision. Most suppliers test only the fatty acid portion of CODEX standards, which alone does not verify purity and can be adulterated by up to 30–40% with other oils and still pass. Adams Group tests all three CODEX markers: fatty acid profile, sterol composition, and tocopherol levels. The company rejects any load showing evidence of adulteration before refining begins.
Adams Group supplies wholesale avocado oil in Conventional, Certified Organic, and Regenerative Organic Certified® (ROC) formats, giving ingredient buyers the sourcing flexibility to meet both quality and sustainability commitments at scale.
Regulatory and Legal Implications
The FDA has identified avocado oil as one of the most frequent targets for economically motivated adulteration—a practice where a premium ingredient is quietly diluted or swapped out for something cheaper. Despite that warning, the industry's track record speaks for itself. What was once a reputational risk has become a legal one.
Following the 2020 and 2023 UC Davis studies, multiple class action lawsuits were filed against brands whose products failed purity testing, putting the entire category on notice. The 2026 findings raise the stakes even further. For brands in this space, the question is no longer whether consumers will notice, but whether their R&D and procurement teams have done enough to protect them when they do. Purity verification is no longer optional; it is the difference between brand equity and brand liability.
Call to Action for Brands
For brands carrying a "100% Avocado Oil" or "Made with Avocado Oil" claim, the 2026 UC Davis findings serve as a supply chain audit in plain sight. They give procurement teams one clear mandate: know exactly what is in your oil, and who can prove it.
To read the full 2026 UC Davis Study, visit: https://www.ucdavis.edu/food/news/avocado-oil-chip-youre-eating-may-not-be-made-pure-avocado-oil. For a full list of the 2026 UC Davis Study chips, mayonnaise and salad dressing brands tested and their results, visit: https://ucdavis.app.box.com/s/6ogs4l0ogplunooktwryr5b1m6k2xr9u.
About Adams Group
Adams Group is a fifth-generation, family-owned food company with over 100 years of agricultural heritage, operating one of the most integrated specialty oils, grains, and seeds businesses in North America. The company's state-of-the-art refinery and laboratory in Arbuckle, California processes avocado for ingredient customers across the food, beverage, and personal care industries. Adams Group supplies avocado oil in Conventional, Certified Organic, and Regenerative Organic Certified® (ROC) formats, each meeting CODEX international purity standards, with full lot traceability from crude intake through finished ingredient delivery. For more information, visit https://adamsgrp.com.
These chips were among the 54 avocado-labeled products tested for avocado oil authenticity in the Wang lab at UC Davis. (Natalie Lopez-Alvarez/UC Davis)