Evaluation of the deleterious health effects of consumption of repeatedly heated vegetable oil.
Level 5 - mechanism / opinion, no new human data
Preclinical animal study
PubMed 28959587 · doi:10.1016/j.toxrep.2016.08.003
What was done
Peroxide values were measured in repeatedly heated cooking oil (RHCO) compared with unheated or singly heated oil. Wistar rats were administered RHCO (heated repeatedly three times) to evaluate histopathological changes in the jejunum, colon, and liver, alterations in antioxidant enzyme levels, blood biochemistry (glucose, creatinine, cholesterol, protein, and albumin), and hematological parameters.
What was found
RHCO demonstrated a higher peroxide value than unheated or singly heated oil. Histopathology showed significant tissue damage in the jejunum, colon, and liver of rats fed oil heated three times. Treated rats showed altered antioxidant enzyme levels, elevated blood glucose, creatinine, and cholesterol, and decreased total protein and albumin levels. Hematological parameters showed no statistically significant differences between groups. The abstract reports no numerical values, effect sizes, or variances.
Why it matters
Repeated heating of cooking oil is a common culinary practice, and these animal findings illustrate that thermal oxidation products can drive oxidative stress, organ damage, and metabolic disturbances.
Limits
The study was conducted entirely in Wistar rats, limiting direct generalizability to human health. The abstract omits sample size, duration of exposure, specific oil composition, and all quantitative measurements and confidence intervals.
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