Long-term storage of red blood cells and correlations between red cell and dietary fatty acids: results from a pilot study.

Levels of red blood cell (RBC) fatty acids were determined at baseline and 12 months after storage at -70 degrees C in 15 postmenopausal women to determine whether storage had a detrimental effect on the stability of fatty acids. Four-day diet records were also completed at baseline, allowing comparisons between RBC fatty acid levels and fatty acid levels computed from recent dietary intake. The major fatty acid composition of RBCs did not change substantially during 12 months of storage, and, in particular, for n-6 and n-3 fatty acids most correlations between baseline and 12-month values were greater than 0.90. We also found strong positive correlations between RBC and dietary fatty acids, including oleic, linoleic (18:2n-6), total n-6, and the polyunsaturated-to-saturated fat ratio. We concluded that frozen RBCs may be a useful measure of recent dietary intake for epidemiological studies.