April 2/Preventive Medicine Week -- According to a study from the U.S., "The long-chain omega-3 (n -3) fatty acids derived from fish, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are associated with a reduced risk of cardiovascular disease and other chronic diseases. Study of the associations between EPA and DHA intake and disease requires a valid biomarker of dietary intake; however, the direct measurement of tissue fatty acid concentrations is expensive and time consuming."

"Because the nitrogen stable isotope ratio (N-15/N-14, expressed as delta N-15) is elevated in fish, we investigated whether delta N-15 is a valid alternative biomarker of EPA and DHA intake. We examined the relation between red blood cell (RBC) delta N-15 and RBC EPA and DHA in a community-based sample of 496 Yup'ik Eskimos with widely varying intake of n -3 fatty acids. We also assessed the correlation between delta N-15 and dietary EPA and DHA intake based on 24-hour dietary recalls and 3-day food records completed by a subset of 221 participants. RBC delta N-15 was strongly correlated with RBC EPA and DHA (r = 0.83 and 0.75, respectively). These correlations differed only modestly by sex and age class. RBC delta N-15 also correlated with dietary EPA and DHA intake (r = 0.47 and 0.46, respectively) and did not differ by sex and age. The results strongly support the validity of RBC delta N-15 as a biomarker of EPA and DHA intake. Because the analysis of RBC delta N-15 is rapid and inexpensive, this method could facilitate wide-scale assessment of EPA and DHA intake in clinical and epidemiologic studies," wrote D.M. Obrien and colleagues, University of Alaska.

Obrien and colleagues published their study in American Journal of Clinical Nutrition ("Red Blood Cell Delta N-15: A Novel Biomarker of Dietary Eicosapentaenoic Acid and Docosahexaenoic Acid Intake." American Journal of Clinical Nutrition, 2009;89(3):913-919).

For more information, contact D.M. Obrien, University of Alaska, Institute Arct Biology, Center Alaska Native Health Research, POB 757000, Fairbanks, AK 99775.

From the April 13, 2009, Prepared Foods E-dition