Fasting Whole Blood as a Biomarker of Essential Fatty Acid Intake in Epidemiologic Studies: Comparison with Adipose Tissue and Plasma

TLDR

Biomarkers may more accurately reflect long‑term essential fatty acid intake than questionnaires, and although adipose tissue is the gold standard, other tissues might be equally valid. The study assessed whether fasting whole blood can serve as a biomarker of long‑term essential fatty acid intake compared with plasma and adipose tissue. The study recruited 200 Costa Rican adults who completed a 135‑item food frequency questionnaire and provided adipose tissue and blood samples, with fatty acids measured by capillary gas chromatography and correlations adjusted for age, sex, and BMI. Whole‑blood correlations with dietary intake were comparable to adipose tissue and superior to plasma, with high correlations to plasma (r = 0.96–0.88) and adipose tissue (r = 0.59–0.67), indicating that fasting whole blood is a suitable and practical biomarker of long‑term essential fatty acid intake.

Abstract

Biomarkers could provide a more accurate measure of long-term intake than questionnaires. Adipose tissue is considered the best indicator of long-term essential fatty acid intake, but other tissues may prove equally valid. The authors evaluated the ability of fasting whole blood, relative to fasting plasma and adipose tissue, to reflect fatty acid intake. Costa Rican men (n = 99) and women (n = 101) completed a 135-item food frequency questionnaire and provided adipose tissue and blood samples from 1999 to 2001. Fatty acids were identified by using capillary gas chromatography. Correlation coefficients adjusted for age, sex, and body mass index were calculated. Diet-tissue correlation coefficients for alpha-linolenic acid and linoleic acid, respectively, were 0.38 and 0.43 in whole blood, 0.51 and 0.52 in adipose tissue, and 0.39 and 0.41 in plasma. High correlations were observed between whole-blood alpha-linolenic and linoleic acid and adipose tissue (r = 0.59 and r = 0.67) and plasma (r = 0.96 and r = 0.88), respectively. Results show that fasting whole blood is a suitable biomarker of long-term essential fatty acid intake, and its performance is comparable to that of fasting plasma. Thus, fasting whole blood could be the sample of choice in epidemiologic studies because of its ability to predict intake, its accessibility, and minimum sample processing.