Use of dried blood for measurement of trans fatty acids

BACKGROUND Fatty acid measurements especially trans fatty acid has gained interest in recent times. Among the various available biomarkers, adipose tissue is considered to be the best for the long term dietary intake but the invasive nature of tissue aspiration reduces its utility. Phlebotomy is a much less invasive method of sample collection when a large number of participants are involved in the study and therefore is an alternative, most suitable for large population based studies. In the present study fatty acid (with special emphasis on trans fatty acid) extraction from blood spotted and dried on filter paper was carried out to simplify the sample collection procedure and transportation. METHODS Blood samples were collected from 19 healthy volunteers. The blood was spotted (30 spots of 10 microl each) on filter paper, dried at room temperature and stored at 4 degrees C in zip-lock poly bags. For comparison whole blood stored at -70 degrees C was simultaneously analyzed. RESULTS A good agreement was seen between trans fatty acid values obtained in dried blood and whole blood as evident from the pearson correlation coefficients ('r' for monounsaturated (trans) 0.70 and for polyunsaturated (trans) 0.692 respectively). The intraclass correlation coefficient for monounsaturated trans was 0.805 and for polyunsarurated trans was 0.776. CONCLUSION Dried blood spots can be used for trans fatty acid analysis.