Public Health Nutrition

Research Article

Dietary conjugated linoleic acid (CLA) intake assessment and possible biomarkers of CLA intake in young women

Dorothee Fremanna1 c1, Jakob Linseisena1a2 and Günther Wolframa1

a1 Lehrstuhl für Ernährungslehre, Department für Lebensmittel und Emährung, Technische Universität München–Weihenstephan, Alte Akademie 16, D-85350 Freising, Germany

a2 Deutsches Krebsforschungszentrum, Abteilung für Klinische Epidemiologie, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany

Abstract

Objective: The habitual intake of the conjugated linoleic acid (CLA) isomer C18:2 c9t11 (rumenic acid, RA) was assessed and compared with plasma biomarkers.

Design: The newly developed food-frequency questionnaire (FFQ) comprised 46 food items and was validated by means of a 7-day estimated record (7-d ER). Additionally, the dietary intake results of the FFQ, 7-d ER, the last day (1-d ER) and the last two days (2-d ER) before blood sampling of the 7-d ER were compared to the content of C18:2 c9t11 in plasma phospholipids (PL) and triglycerides (TG) as possible biomarkers.

Setting: Metabolic unit of a university institute.

Subjects: Fifty-seven students completed both dietary instruments. From all participants fasting blood samples were taken.

Results: Mean daily intake of rumenic acid was 246 mg day−1 and 323 mg day−1 as measured by the FFQ and the 7-d-ER, respectively. The degree of correspondence between both assessment methods was acceptable; this is indicated by a total kappa value of κ = 0.31 (P < 0.01) and a Pearson correlation coefficient of r = 0.46 (P < 0.01). Rumenic acid content in plasma triglycerides was twice as high as found in phospholipids. The correlation between the intake results gained with the 7-d ER and the plasma PL contents of C18:2 c9t11 was statistically significant; this was also true for the C18:2 c9t11 values in plasma TG compared with the intake results of one or two days before blood sampling.

Conclusions: Regarding RA intake, the FFQ data revealed an acceptable degree of correspondence with the 7-d ER data but failed to show significant correlations to the potential biomarkers. However, with respect to the results of the 7-d ER, the RA content in plasma PL and TG are possible biomarkers of short-term and medium-term intake, respectively.

(Received January 29 2001)

(Accepted June 15 2001)

Correspondence

c1 *Corresponding author: Email: dorothee.fremann@weihenstephan.de

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