¹INRA, Unité de Nutrition Lipidique, Dijon, France

²Department of Human Biology, Maastricht University, The Netherlands

³Laboratoire de Nutrition Humaine, CRNH, Université d'Auvergne, Clermont-Ferrand, France

⁴Queen Margaret University College, Edinburgh, Scotland

⁵Scottish Crop Research Institute, Dundee, Scotland

⁶Raisio Group, Raisio, Finland

⁷Lesieur Alimentaire, France

⁸Cardiovascular Research Unit, University of Edinburgh, Scotland; on behalf of the investigators of the TransLineE project†

Correspondence to: R A Riemersma, Cardiovascular Research Unit, Hugh Robson Building, George Square, Edinburgh EH8 9XF, Scotland.

The investigators of the TransLineE project are: L Brétillion, JM Chardigny, JL Sébédio (INRA, Dijon); B Beaufrère, E Verdier (CRNH, Clermont-Ferrand); WW Christie, CE Fernie, CM Scrimgeour (SCRI, Dundee); RP Mensink, SHF Vermunt (Maastricht University); RA Elton, A Macvean, RA Riemersma (University of Edinburgh); RA Armstrong (Queen Margaret University College, Edinburgh); E Rock (INRA-U3M, St Genes Champanelle); R Grappin (INRA-SRTAL, Poligny); G Hénon (Lesieur Alimentaire, Neuilly); J Niemelä (Raisio Group, Raisio); JP Noël (CEA-Saclay, Gif sur Yvette).

Objective: To collect (i) baseline data and (ii) execute a large multicentre study examining the effect of trans -linolenic acid on its incorporation into plasma lipids and on risk factors for coronary heart disease.

Design: Male volunteers were recruited and the habitual diet assessed by a 4-d weighed record. Fatty acid composition of plasma and platelet lipids were determined by gas chromatography at baseline. After a 6 week run-in period on a trans 'free' diet, male volunteers were randomised to consume 0.6 % of energy trans -linolenic acid or to continue with a diet 'low' in trans -linolenic acid for 6 weeks.

Setting: Three European university research departments supported by the research and development departments of the food industry.

Subjects: Male volunteers (88) recruited by local advertisement.

Methods: Replacement of 30 % of the fat of the habitual diet by margarine, oil and foods. Rapeseed oil was deodorised especially to produce the trans 'free' and 'high' trans foods for this study. The incorporation and conversion of trans -linolenic acid into plasma lipids and platelets was assessed by gas chromatography and dietary compliance was verified by 4-d weighed record.

Results: Less trans -linolenic acid isomers are incorporated into human plasma lipids in French volunteers than in Dutch or Scottish volunteers consuming their habitual diets. Trans 'free' -linolenic acid-rich oil can be produced by careful deodorization during refining. The 'high' trans diet provided 1410±42 mg/d trans isomers of -linolenic acid, whilst the 'low' trans group consumed 60±75 mg/d. The change in plasma lipid and platelet fatty acid composition documented that trans linolenic isomers are incorporated and converted to a trans isomer of eicosapentaenoic acid. Only the 15-trans -linolenic acid is incorporated into plasma cholesteryl esters. The group consuming low trans diet had a slightly higher intake of fat, especially saturated and monounsaturated fat.

Conclusions: Trans 'free' rapeseed oil, rich in -linolenic acid, can be produced by careful deodorization. Dietary records show good compliance. Dietary trans isomers of -linolenic acid are incorporated in plasma lipids and converted to long-chain polyunsaturated fatty acids. Their effects on risk factors for coronary heart disease and their metabolism will be reported elsewhere.

Sponsorship: European Commission (FAIR 95-0594 grant).

European Journal of Clinical Nutrition (2000) 54, 104-113

-linolenic acid; trans fatty acid; diet; trial; fatty acid composition; plasma lipids; deodorization; trans polyunsaturated fatty acids