Effect of a low-fat diet on fatty acid composition in red cells, plasma phospholipids, and cholesterol esters: investigation of a biomarker of total fat intake.
BACKGROUND
The utility of fatty acids (FAs) as biomarkers of total fat intake is unknown.


OBJECTIVE
We compared FA changes in red cells (RCs), plasma phospholipids (PLs), and cholesterol esters (CEs) in response to a low-fat diet (LFD) and a moderate-fat diet (MFD) and assessed whether individual or combination of FAs predict LFD.


METHODS
Postmenopausal women (n = 66) were randomly assigned to receive an LFD (17% of energy from fat) or an MFD (34% of energy from fat) for 6 wk. All foods were provided. FAs in diets and blood were determined by gas-liquid chromatography. FA changes between baseline and end of study were compared across diets by using t tests. FA predictors of an LFD were selected by logistic regression.


RESULTS
Many FAs in RCs, PLs, and CEs responded differently to the 2 diets. Changes from baseline with an LFD for palmitic acid (16:0) (3-11% increase), behenic (22:0) and lignoceric (24:0) acids (3-20% decrease, in RCs and PLs only), cis-monounsaturated FA (MUFA) (25-35% increase), linoleic acid (18:2n-6) (11-13% decrease), trans octadecanoic acids (trans 18:1) (7-20% decrease), and n-6 highly unsaturated FA (HUFA) (2-8% increase) were significantly different from changes with an MFD. Individually, 18:2n-6 and trans 18:1 were strong predictors of an LFD [receiver operating characteristic (ROC) curves: 0.92-0.80). A logistic regression model with trans 18:1, 18:2n-6, and vaccenic acid (18:1n-7) predicted an LFD with high specificity and sensitivity (ROC curves: 0.99).


CONCLUSIONS
Saturated FA, cisMUFA, n-6 HUFA, and exogenous FAs greatly differed in their response to the LFD and MFD. Parallel responses were observed in RCs, PLs, and CEs. A model with a combination of FAs almost perfectly differentiated the consumption of 34% fat from that of 17% fat.
Cancer Prevention Program, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA. iking@fhcrc.org
Irena B
IB
King
Rozenn N
RN
Lemaitre
Mark
M
Kestin
D000368:Aged; D015415:Biomarkers / Q000097:blood; D002788:Cholesterol Esters / Q000097:blood / Q000737:chemistry*; D002849:Chromatography, Gas; D015930:Diet Records; D018752:Diet, Fat-Restricted; D004912:Erythrocytes / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis*; D015525:Fatty Acids, Omega-3 / Q000032:analysis; D043371:Fatty Acids, Omega-6 / Q000032:analysis; D005260:Female; D006801:Humans; D007536:Isomerism; D016015:Logistic Models; D008875:Middle Aged; D010743:Phospholipids / Q000097:blood / Q000737:chemistry*; D017698:Postmenopause; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity
D015415:Biomarkers; D002788:Cholesterol Esters; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D010743:Phospholipids