Feeding rats with used cooking oil elevates malondialdehyde, TNF-α, and creatinine compared to tempe fried with used oil.
Level 5 - mechanism / opinion, no new human data
Animal study without human clinical data
PubMed 39280278 · doi:10.52225/narra.v4i2.853
What was done
Healthy male Sprague-Dawley rats (aged 2–3 months, 100–200 g) were randomly assigned to seven groups for a 4-week dietary intervention (15 g/day): (1) regular diet control; (2) tempe deep-fried in 5× used palm oil; (3) tempe deep-fried in 5× used coconut oil; (4) tempe deep-fried in 5× used olive oil; (5) 5× used palm oil alone; (6) 5× used coconut oil alone; and (7) 5× used olive oil alone. Blood samples were collected after four weeks to assess complete blood count and serum biochemistry including malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and creatinine.
What was found
Final body weight and weight gain increased significantly in all three fried tempe groups and the used palm oil group compared to control, used coconut oil, and used olive oil groups. Serum TNF-α and creatinine increased significantly in the used coconut oil and used olive oil groups (p < 0.05). Only the used olive oil group had a significantly increased MDA level compared to all other groups (p < 0.05). The abstract provides p-value thresholds but does not report exact numerical means or standard deviations.
Why it matters
Feeding isolated reused cooking oils resulted in greater inflammatory, oxidative, and renal markers than feeding a whole food matrix (tempe) fried in those same oils, suggesting that feeding pure used oil may not accurately reflect the physiological impact of eating fried whole foods.
Limits
This was an animal study conducted exclusively in male Sprague-Dawley rats over a short 4-week duration, limiting direct clinical translation to humans. Total sample size (n) and exact quantitative biochemical values were not reported in the abstract.
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