BackgroundThe metabolic effects of consuming mildly oxidized lipids as compared to highly oxidized lipids are not well documented.ObjectiveOur objective was to investigate if food containing heated soybean oil (SO) alters fat mass and glucose tolerance in C57BL/6J mice at 5 and 10 weeks.MethodsSix week old male C57BL/6J mice were purchased and were randomly divided into four groups (n=8/group) and were fed a low fat diet with either unheated SO or SO heated for 3 (3h‐HO), 6 (6h‐HO), or 9 (9h‐HO) hours for 5 weeks. Food consumption was recorded every 3–4 days, and body weights were recorded every week. Blood glucose levels were measured after a 16 h fast.ResultsThere were no significant differences in weight gain between the groups. Average daily food consumption for mice fed unheated oil, 3h‐HO, 6h‐HO, and 9h‐HO was 18.64g, 19.08g, 19.28g, and 19.68g, respectively. Mean blood glucose levels for mice fed unheated oil, 3h‐HO, 6h‐HO, and 9h‐HO were (mean ± SD) 97.38 ± 21.37 mg/dL, 76.75 ± 9.71 mg/dL, 83.63 ± 12.92 mg/dL, 98 ± 19.38 mg/dL, respectively (overall significance, p = 0.038; 3h‐HO vs. 9h‐HO, p = .094).ConclusionA 5 week exposure to heated oils does not alter weight gain when compared to unheated oil; however, fasting blood glucose levels were higher in the 9h‐HO group compared to 3h‐HO group (p>; 0.05), which might indicate the beginning signs of glucose intolerance.

The objective of this study was to investigate if the level of oxidation of soybean oil determines the accumulation of lipids in 3T3‐L1 adipocytes.MethodsSoybean oil (SO) was unheated or heated for 3, 6 or 9 hours at 190°C to generate oils with increasing levels of oxidation as determined by the levels of conjugated dienes (CD) and conjugated trienes (CT). 3T3‐L1 cells were grown to confluence in 24 well plates and then exposed to DMEM supplemented with or without 0.1%, 0.01% and 0.001% of heated or unheated SO for 24 hrs either prior to or, after differentiation. After treatment, cells were stained with oil red O to determine the accumulation of lipids.ResultsProgressive heating of soybean oil created oils with increasing amounts of oxidized lipids (ratio of CD/CT was 1.92, 2.33, 3.1 and 3.56 for the unheated, 3hr, 6hr and 9hr heated oils, respectively). The intensity of oil red O staining was similar in 3T3‐L1 cells that were treated with vehicle or unheated oil for 24hr in undifferentiated cells but was lesser in the cells treated with 3hr heated SO. More interestingly, there was no oil red staining when cells were treated with the 6hr and 9hr heated oils, suggesting a loss of lipid accumulation. In experiments where SO was added to differentiated 3T3‐L1 cells for 24 hrs, there was no obvious effect of the oils on oil red O staining.ConclusionThese results demonstrate that exposure of pre‐adipocytes to oils with higher ratios of oxidized lipids inhibits the adipocyte lipid accumulation. Since this effect is not seen in cells that are differentiated, it suggests that heated oils could be suppressing regulators of adipocyte differentiation.Grant Funding Source : None