Development and validation of a combined method for the biomonitoring of omega-3/-6 fatty acids and conjugated linoleic acids in different matrices from human and nutritional sources.

Background: During the last decade, the contribution of omega-3 and -6 long chain-polyunsaturated fatty acids (LC-PUFA) and conjugated linoleic acids (CLA) to the prevention and development of many inflammatory and cardiovascular diseases has been of growing interest. In order to investigate the etiology of these diseases, rapid, combined and comparable methods are invaluable for monitoring both the intake and the incorporation of these fatty acids (FA).

Methods: The fatty acid methyl esters (FAME) were analyzed using a gas chromatography/flame ionization detector (GC-FID) system and quantified with an internal standard (C18:0 iso).

Results: An effective and rapid protocol for sample preparation and the analysis of FAME was developed and validated. The comparison of different extraction methods showed that the Hara and Radin method gave the best results for serum and erythrocyte membranes. Excellent mean within-day and day-to-day precisions for serum, erythrocytes and cow's milk LC-PUFAs demonstrated the high reproducibility of the method. Recovery rates for FAMEs in serum and milk were close to 100%. In addition, high mean method linearity (R(2)) (>0.99) was shown for serum, erythrocytes and cow's milk. The sensitivity for FA achieved by GC analysis was acceptable.

Conclusion: With the newly adapted protocols, combined and rapid analyses of up to 46 FAMEs, including CLAs and omega-3/-6 LC-PUFAs, can be conducted with high reliability and reproducibility using serum, erythrocyte membranes or cow's milk. This provides a novel tool that can be easily implemented in epidemiological studies or clinical diagnostics.