When you fry potato chips over and over, a specific type of fat called trans-epoxy fatty acid builds up more than other similar fats.

Scientific Claim

During deep-frying of potato chips in high-oleic sunflower oil, concentrations of trans-epoxy fatty acids increase with frying cycles, exceeding those of cis-epoxy fatty acids by the second day.

Original Statement

“The concentrations of both E,E-9-/13-hydroperoxy-LA and E,E-9-/13-hydroxy-LA increase with the frying cycles, which is also found for the concentration of trans-epoxy-FA. The increase in trans-epoxy-FA is more pronounced than that of the corresponding cis-epoxy-FA, exceeding their concentrations on the second day of frying.”

From study:Trans-Hydroxy, Trans-Epoxy, and Erythro-dihydroxy Fatty Acids Increase during Deep-Frying

Evidence Quality Assessment

Claim Status

appropriately stated

Study Design Support

Design cannot support claim

Appropriate Language Strength

definitive

Can make definitive causal claims

Assessment Explanation

The claim uses definitive language only for observed concentration changes under specific conditions, which matches the abstract’s descriptive reporting. No causal or generalizable claims are made. Based on abstract only - full methodology not available to verify

Evidence from Studies

Supporting (1)

Trans-Hydroxy, Trans-Epoxy, and Erythro-dihydroxy Fatty Acids Increase during Deep-Frying

Cross-Sectional Study

In Vitro

2023 May 17

The study found that when potato chips are fried repeatedly in this special oil, harmful trans-epoxy fats build up faster than their cis counterparts, and by the second day, there’s more of the trans kind — just like the claim says.

Contradicting (0)

No contradicting evidence found

Source Study

Trans-Hydroxy, Trans-Epoxy, and Erythro-dihydroxy Fatty Acids Increase during Deep-Frying

Score: 3

DOI: 10.1021/acs.jafc.3c00964

Similar Assertions

When oil is reused for frying, one kind of breakdown product (erythro-dihydroxy) builds up more than another (threo-dihydroxy), because it comes from a different type of fat that forms more during heating.

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As oil is reused for frying, a specific type of oxidized fat called E,E-hydroxy-LA becomes more common.

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When oil is reused for frying, some unstable fat breakdown products disappear, but the stable ones they turn into don’t change much in amount.

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Scientists think that looking at the balance between different types of broken-down fats might help tell how much oil has been used for frying.

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When you fry potatoes over and over using avocado or olive oil, the oil gets more acidic, more oxidized, and loses some of its natural antioxidants.

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