Clinical and epidemiologic studies showed that among dietary factors the type of fatty acids (FAs) in the diet plays an important role in determining risk of chronic disease. The aim of our study was to determine the levels of Trans FA (TFA) in edible oil samples consumed in Tehran, Iran analyzed by gas chromatograph (GC). The mean of total TFA was 0.45% ranging from (0.11% - 1.61%) for liquid frying oils and 2.92% ranging from (0.46% - 5.40%) for solid oils. The major TFA observed in these two groups was elaidic acid in solid oils. The highest content of total saturated fatty acid (SFA) was detected in solid oils with average of 32.07 and palmitic acid was the major SFA in these four groups. Linoleic and linolenic acid are the most important poly unsaturated fatty acid (PUFA). The variance in the percentage of TFA in the edible oils probably resulted from differences in the type of oils, quality, heating, processing technique and storage condition of the edible oils. The results indicated that, edible oils contain considerable proportions of trans fatty acids. Therefore, it is important to assess the content of TFA in edible oils in Iran.
Fatty acids are unique macromolecules as they act as biological modulators of transcription factors and regulate their own metabolism by controlling the activity or abundance of transcription factors of fatty acid metabolism either by RNA processing and RNA stability. Peroxisome Proliferator Activated Receptor (PPAR-γ) and Sterol Regulatory Element Binding Protein (SREBP-1c) are transcription factors expressed primarily in adipose tissue. We have studied the relation of fatty acid including trans fatty acid assessed in adipose tissue with the transcription factors. Adipose tissue was collected from 50 healthy subjects undergoing elective abdominal surgery. Fatty acid was assessed in the tissue by gas chromatography. The expressions of PPARγ and SREBP-1c were studied by real time RT-PCR. The expressions of PPARγ and SREBP1c were significantly correlated (r = 0.4 p < 0.005). The trans fatty acid did not show any significant correlation with expression but significant correlation was observed between DHA (Docosahexaenoic acid) and PPARγ expression (r = 0.33 p < 0.03) which remained significant (r = 0.87, p < 0.0001) after being adjusted for BMI and insulin. An upregulation of PPARγ led to decreased levels of SREBP1c. In conclusion, trans fatty acid did not affect the expressions of PPAR-γ and SREB1c in this study.