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

by Ana Baylin, Mi Kyung Kim, Amy Donovan-Palmer, Xinia Siles, Lauren Dougherty, Paula Tocco, Hannia Campos

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 α-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 α-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.
pufa

200 individuals from Costa Rica were asked about their food intake to determine estimated fatty acid profiles, had adipose tissue samples taken, as well as whole-blood and plasma (which excludes e.g. red blood cells). Correlations were then compared between these sources. As expected, adipose fatty acids pretty closely resembled (estimated) dietary intake the closest. For linoleic acid in particular, the correlation between plasma and whole-blood was pretty strong too. Average whole-blood LA (22.38%) was higher than adipose (15.71%) and estimated diet (18.87%), and plasma was even higher (28.09%). Arachidonic acid, on the other hand, seemed strongly controlled: despite extremely low intakes and adipose levels (<1%), plasma (6%) and whole-blood levels (9%) were quite high.

Original source: https://academic.oup.com/aje/article/162/4/373/105354