Incorporation of Fatty Acids as a Biomarker of Dietary Intake and Source is Fatty Acid and Blood Fraction Specific in CD-1 Mice

Abstract Objectives Accurate biomarkers of fatty acid (FA) intake and source (e.g., diet-derived FA) are an important assessment tool to study the role of dietary fat quality on metabolic health. The purpose of this study was to assess the incorporation of unique, dietary FA from fish oil, echium oil, and dairy fat into the red blood cell membranes (RBCM), plasma phospholipids (PPL), and plasma cholesterol esters (PCE) of genetically-outbred CD-1 mice. Methods At one month of age, mice were assigned to one of four isocaloric diets consisting either of a control fat blend or the control fat blend supplemented (30%) with fish oil, echium oil, or dairy fat (n = 10/diet/sex). After 52 weeks of feeding, cardiac blood was collected for FA analysis of RBCM, PPL, and PCE using gas-liquid chromatography. Results Expectedly, a higher proportion of fish-derived FA (eicosapentaenoic acid and docosahexaenoic acid) was observed in the RBCM and PCE of fish oil-fed mice (P < 0.0001). Accordingly, a greater proportion of echium oil-derived γ-linolenic acid was incorporated into all blood fractions of echium oil-fed mice (P < 0.0001). Yet, stearidonic acid, specific to echium oil, was not detected in the RBCM of mice, and no differences in the proportion of stearidonic acid were found in the PPL and PCE. Odd-chain FA (pentadecanoic acid and heptadecanoic acid) were not exclusively enriched in the blood fractions of dairy-fed mice. Conversely, trans-palmitoleic acid, vaccenic acid, rumenic acid, and branched-chain FA were differentially incorporated into the PPL and PCE, while not detected in the RBCM. Conclusions In summary, unique, diet-derived FA are differentially incorporated into the blood fractions of mice, indicating that the incorporation of dietary FA into blood fractions is highly dependent upon the FA species. Therefore, diet-derived FA cannot be used universally as a reliable biomarker to validate dietary FA source in mice, rather, the specific FA and blood fraction must be carefully considered. Funding Sources Armin Grams Memorial Research Award, UVM Robert Larner, M.D. College of Medicine; USDA-NIFA Hatch Fund (accession number: 1,006,628).