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Monoepoxy fats are better absorbed than diepoxy fats in women (17 +/- 4 vs. 8 +/- 1% of dose, P = 0.02). This difference in absorption is important when considering the relative toxicity of epoxidized material in the food chain.

Relative absorption of conjugated linoleic acid as triacylglycerol, free fatty acid and ethyl ester in a functional food matrixConjugated linoleic acid (CLA) shows potential benefits in a number of medical conditions, making it a possible target for incorporation into a functional food. Until recently, clinical trials were conducted with various mixtures of CLA isomers, encapsulated as the free acid. The purpose of this study was to examine a mixture of two specific CLA isomers (9c,11t and 10t,12c), incorporated into a functional food either as triacylglycerol, free fatty acid or fatty acid ethyl ester. Differences in absorption between the lipid forms and between the isomers were investigated. The palatability of the different functional-food formulations was also studied. Significantly less CLA was absorbed into chylomicrons over six hours when fed as fatty acid ethyl ester than when either the triacylglycerol or free fatty acid forms were fed. Further work is recommended, to examine fatty acid ethyl ester absorption over longer periods of time. Most subjects reported that the fatty acid formulation had poor taste characteristics. We conclude that CLA as triacylglycerol is the most suitable form for incorporation into a functional food and that the 9c,11t and 10t,12c CLA isomers are absorbed similarly into chylomicrons.Keywords: Absorption, CLA, functional food, triacylglycerol, ethyl ester. IntroductionConjugated linoleic acid (CLA) is the collective name given to C18 fatty acid positional and geometric isomers, containing two conjugated double bonds. CLA is a minor component of dairy and ruminant fats and is also a product of autoxidation and partial hydrogenation of polyunsaturated fats. There is increasing interest in CLA, as in animal trials it has shown potentially beneficial effects on a number of medical conditions, including cancer and diabetes, as well as altered body composition. The results from human studies are less conclusive [1] but its potential as the active component of a functional food is being explored [2,3].A major difference between a functional food and a pharmaceutical is that, although both must provide the active ingredient in a form that ensures a reasonable level of uptake, the functional food has also to be appealing to the consumer for long-term consumption as part of the daily diet. Most of the previous human studies have used CLA as the free acid, usually in capsules, containing a variety of isomeric mixtures, since this was the only material that was readily available. However, the increased interest in CLA has led to the production of CLA with excellent isomeric purity [4], both as free acid and more recently as triacylglycerol.The FunCLA project (funded by EU grant QLK1-CT99-00076) was set up to apply a functional food approach to examining two specific CLA isomers, with regard to their individual effects on body composition, diabetes, metabolic parameters and hyperlipidaemia in humans. The object of the first part of the project was to examine the absorption of a mixture co...

Dietary trans monoenes have been associated with an increased risk of heart disease in some studies and this has caused much concern. Trans polyenes are also present in the diet, for example, trans α‐linolenic acid is formed during the deodorisation of α‐linolenic acid‐rich oils such as rapeseed oil. One would expect the intake of trans α‐linolenic acid to be on the increase since the consumption of rapeseed oil in the western diet is increasing. There are no data on trans α‐linolenic acid consumption and its effects. We therefore carried out a comprehensive study to examine whether trans isomers of this polyunsaturated fatty acid increased the risk of coronary heart disease. Since inhibition of Δ6‐desaturase had also been linked to heart disease, the effect of trans α‐linolenic acid on the conversion of [U‐13C]‐labelled linoleic acid to dihomo‐γ‐linolenic and arachidonic acid was studied in 7 healthy men recruited from the staff and students of the University of Edinburgh. Thirty percent of the habitual fat was replaced using a trans ‘free’‐ or ‘high’ trans α‐linolenic acid fat. After at least 6 weeks on the experimental diets, the men received 3‐oleyl, 1,2‐[U‐13C]‐linoleyl glycerol (15 mg twice daily for ten days). The fatty acid composition of plasma phospholipids and the incorporation of 13C‐label into n‐6 fatty acids were determined at day 8, 9 and 10 and after a 6‐week washout period by gas chromatography‐combustion‐isotope ratio mass spectrometry. Trans α‐linolenic acid of plasma phospholipids increased from 0.04 ? 0.01 to 0.17 ? 0.02 and cis ? ‐linolenic acid decreased from 0.42 ? 0.07 to 0.29 ? 0.08 g/100 g of fatty acids on the high trans diet. The composition of the other plasma phospholipid fatty acids did not change. The enrichment of phosphatidyl 13C‐linoleic acid reached a plateau at day 10 and the average of the last 3 days did not differ between the low and high trans period. Both dihomo‐γ‐linolenic and arachidonic acid in phospholipids were enriched in 13C, both in absolute and relative terms (with respect to 13C‐linoleic acid). The enrichment was slightly and significantly higher during the high trans period (P<0.05). Our data suggest that a diet rich in trans α‐linolenic acid (0.6% of energy) does not inhibit the conversion of linoleic acid to dihomo‐γ‐linolenic and arachidonic acid in healthy middle‐aged men consuming a diet rich in linoleic acid.

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