Estimation of cis-9, trans-11 conjugated linoleic acid content in UK foods and assessment of dietary intake in a cohort of healthy adults

Abstract

Dietary conjugated linoleic acid (CLA) from ruminant-derived foods may be potentially beneficial to health. The quantity of cis-9, trans-11 CLA and trans-10, cis-12 CLA in a range of UK foodstuffs (112 foods) was determined using triple-column silver ion HPLC. The cis-9, trans-11 CLA content ranged from 1·9 mg/g lipid (mild Cheddar) to 7·3 mg/g lipid (processed cheese) in cheeses, from 0·9 mg/g lipid (ice cream) to 3·7 mg/g lipid (double cream) in non-cheese dairy products, and from 2·9 mg/g lipid (Swedish meatballs) to 6·0 mg/g lipid (minced lamb) in meat products. cis-9, trans-11 CLA concentrations for chocolate and sweets ranged from 0·1 mg/g lipid (hot chocolate) to 4·8 mg/g lipid (buttermint). The trans-10, cis-12 CLA isomer was undetected or negligible in the food samples examined. To provide information about dietary cis-9, trans-11 CLA intakes in the UK, a study was performed to estimate the daily intake of CLA in a cohort of eighteen healthy volunteers (nine female and nine male; aged 21-60 years; mean BMI ¼ 24·0 kg/m 2 (SD 2·2)) with a 7-d weighed food record. This information combined with the CLA isomer contents of UK foodstuffs was used to estimate the daily intake of the cohort. The mean daily intake of cis-9, trans-11 CLA was estimated to be 97·5 (SD 73·3) mg/d. Due to its potential health benefits, it is important to determine the CLA content of food and dietary intake as these data will be useful in determining the role of CLA in health and disease. Conjugated linoleic acid: Dietary conjugated linoleic acid intake: Conjugated linoleic acid food content: Silver ion HPLCConjugated linoleic acid (CLA) is the collective term for positional and geometric isomers of octadecadienoic acid (linoleic acid 18 : 2n-6), which contain two conjugated double bonds. The principal dietary sources of CLA are meat and dairy products derived from ruminants. The cis-9, trans-11 isomer of CLA is the most abundant dietary form and is derived from incomplete biohydrogenation of linoleic acid by the micro-organism, Butyrivibrio fibrisolvens, in the rumen (1) or from the activity of D 9-desaturase on vaccenic acid (VA) in bovine mammary tissue (2) . CLA has been reported to induce potentially favourable effects on body composition, carcinogenesis, atherogenesis, glucose tolerance and immune function (3 -10) . Many of these effects have been observed in animal models and cell cultures, but several human intervention studies have also demonstrated beneficial effects (11 -15) . It is thought that the two CLA isomers that are responsible for such effects are cis-9, trans-11 CLA and trans-10, cis-12 CLA.Due to the potential health benefits associated with CLA consumption, several studies have been carried out to ascertain the CLA content of foodstuffs using analytical techniques such as silver ion HPLC (16) and GC (17) . Chin et al. (18) used GC to demonstrate that the CLA content of ruminant products ranged from 2·7 mg/g fat in veal to 5·6 mg/g fat in lamb and from 2·9 mg/g fat in Romano cheese to 7·1 mg/g fat in Brick ch...

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