Comparison of Dietary Fat Intake Using Food Records vs. RBC Fatty Acid Biomarkers in a Multiethnic Population—The Federal Women Study

Erythrocyte membrane fatty acids (RBC FA) may be a useful biomarker of dietary fat type to assess its impact on health and disease. Our objective was to examine the association of dietary fat type and RBC FA composition in 2 groups of women of African descent (blacks) compared to whites. Dietary fat type was assessed with food records (5±2 days [mean±SD]) and RBC FA composition (mol%) by gas chromatography in 1federally employed women (53% African American, 14% African immigrants, 33% white; age 44±9y, range 24-62y, BMI 30.5±5.9 kg/m², range 20.3-45.2 kg/m²). Dietary fat type (SFA, MUFA, n-3 PUFA, n-6 PUFA, and trans FA) was calculated as a proportion of total dietary fat. Blacks reported consuming higher SFA and n-6 PUFA (all P<0.05). Dietary report of MUFA, trans FA or n-3 PUFA intake were similar by race (all P≥0.20). In contrast, when RBC FA composition was measured, blacks had higher MUFA and n-3PUFA (both P<0.05). RBC composition of SFA, n-6 PUFA and trans FA were similar by race (all P>0.05). Spearman correlations were calculated to determine the relationship between dietary FA and RBC FA. There was a positive correlation between dietary FA and RBC n-6 PUFA (r=0.3, P<0.02).

In summary, RBC FA was a good marker of n-6 PUFA intake, however, food records appeared to provide a more informative assessment of overall dietary fat type exposure.