Researchers at the University of California, Davis bought 54 packaged foods that listed avocado oil as their only oil, tested them, and found that 48 contained cheaper oils not listed on the label.
That is 89 percent. Broken down by category: 93 percent of chips failed, 71 percent of mayonnaises failed, and 100 percent of salad dressings failed.
The study was published in Applied Food Research and announced by UC Davis on July 15. The products were bought in 2025 and 2026 from online retailers and California stores. UC Davis states plainly that they represent only a portion of the market.
The comparison built into the study is what gives the number weight. The same team ran the same tests on 20 processed foods labeled with olive oil. One failed.
How the Testing Worked
Every oil carries a chemical signature. Researchers measure fatty acids and sterols, which differ among oils in ways that persist in the finished product, and compare a sample against what pure avocado oil should look like.
The obvious objection is that processing might scramble the signature. Deep frying, blending, and emulsifying are harsh processes, and if they alter the fingerprint enough, a pure product could appear adulterated.
Wang's team tested that directly rather than assuming it away. They found fatty acids and sterols changed minimally through processing.
They also built in slack for natural variation. Geographic origin and avocado variety shift these markers, so the researchers allowed a 10 percent margin of deviation before calling a sample adulterated. Eighty-nine percent of the avocado products failed anyway.
Two features of this study make it more credible than most food-testing headlines. It included a control category, olive oil, run through identical methods, which is what turns a scary number into a meaningful comparison. And UC Davis states the study received no outside funding, which matters in a category where industry-funded purity claims circulate freely.
The university has also published a media kit listing the brands tested, the results, and the study's limitations.
Why Olive Oil Passed, and Avocado Oil Did Not
The gap is not about the plants. It is about scrutiny.
Olive oil authenticity has been studied, tested, and litigated for decades. Standards exist, testing infrastructure exists, and buyers along the supply chain expect verification. Avocado oil is a newer, more expensive category that has not been monitored to the same extent, leaving less protection against misleading labels.
Price is the motive. Pure avocado oil is substantially more expensive than common seed oils, and a label claim that costs nothing to print can carry a premium that the contents do not justify. UC Davis notes that avocado oil products in the study were priced comparably to olive oil products or higher. In contrast, the olive oil products were overwhelmingly authentic, and the avocado ones were overwhelmingly not.
Selina Wang, professor of cooperative extension in the UC Davis Department of Food Science and Technology and the study's lead author, pointed to the supply chain rather than at brands. Companies often buy oil through third-party brokers or from several suppliers at once, and without testing they may never learn what they received. Adulteration, she said, likely originates with suppliers.
"I don't think there is enough accountability throughout the supply chain," Wang said, describing suppliers of adulterated oil as able to hide behind several layers that make the origin hard to trace.
She added that food companies could do more to verify what they buy. Either way, the outcome for the shopper is the same.
What This Does and Does Not Tell You
This is a labeling and authenticity finding. It is not a safety finding and not a nutrition finding.
Nothing in the study suggests the adulterated products are dangerous. The undisclosed oils are ordinary edible oils. The harm identified here is economic and informational: people paid a premium for something they did not receive.
The study also did not test whether avocado oil is better for you than the oils used as substitutes. That is a separate question, and it matters because a substantial share of the people buying these products are specifically trying to avoid seed oils. For that shopper, the finding is pointed. They are paying extra to avoid an ingredient and, in most of the products tested, getting it anyway.
Whether avoiding seed oils is itself supported by evidence is a genuinely contested question that this research does not address, and readers should be wary of anyone using this study to settle it in either direction.
One more limit worth noting: the results describe 54 products purchased over two years from a specific set of retailers. They do not establish that 89 percent of avocado oil products on every shelf are adulterated.
What a Shopper Can Actually Do
There is no home test, and the failures here were invisible on the package. That constrains the useful advice.
Check the ingredient list rather than the front of the bag. A product marketed as "made with avocado oil" may legally list several oils, and the study focused on products where avocado oil was the only oil named. If other oils appear in the ingredients, the front-of-pack claim is telling you less than it seems to.
Treat price as weak evidence. Products in this study cost as much as or more than their olive oil equivalents and were mostly not what they claimed to be, so paying more bought nothing.
If avoiding seed oils is the goal, whole foods and cooking at home with an oil you buy in a bottle sidestep the problem. However, UC Davis's earlier work found that bottled avocado oil has its own issues: a 2020 study found that 82 percent of commercial bottled avocado oil was rancid or mixed with other oils, and a later study found that 70 percent of private-label oils were rancid or adulterated. Olive oil, by contrast, performed well in this study's control group.
Third-party certification exists but should be read skeptically, since several organizations offering it also sell testing services and publicity around findings like these.
The confirmed finding is that 48 of 54 processed foods labeled with avocado oil contained undisclosed, cheaper oils, compared with 1 failure in 20 olive oil products. The people most affected are shoppers paying a premium specifically for oil composition. The most reasonable action is to read ingredient lists rather than front-of-pack claims, and to weigh whether the premium buys anything. The central uncertainty is where in the supply chain the substitution happens, which this study could not trace.
Frequently Asked Questions
What did the study find? That 48 of 54 processed foods labeled as containing avocado oil were adulterated with cheaper undisclosed oils. By category, 93 percent of chips, 71 percent of mayonnaises, and 100 percent of salad dressings failed.
How were the products tested? By measuring fatty acids and sterols, the chemical fingerprints unique to each oil, and comparing them against pure avocado oil with a 10 percent margin allowed for natural variation.
Could processing have caused false failures? The researchers tested that specifically and found frying, blending, and emulsifying changed the markers minimally. They also used conservative criteria.
Did olive oil products have the same problem? No. Of 20 olive oil-labeled products run through identical tests, one failed. Olive oil authenticity has been scrutinized and standardized for decades; avocado oil has not.
Is adulterated avocado oil dangerous? The study did not identify a safety hazard. The substituted oils are ordinary edible oils. The harm identified is economic, since consumers paid a premium for something they did not get.
Who is responsible? The lead author said adulteration likely originates with oil suppliers and that brands may not know, while adding that companies could do more to verify what they buy.
How can I tell if a product is affected? You generally cannot from the package. Read the full ingredient list rather than front-of-pack claims, and treat a higher price as weak evidence of authenticity.
