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Title: Conjugated linoleic acid intake in the UK and effects of supplementation on body composition and lipid metabolism
Author: Mushtaq, Sohail
ISNI:       0000 0004 2678 371X
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2006
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Conjugated linoleic acid (CLA) is the term used to describe the geometric and positional isomers of octadecadienoic acid (18:2) with conjugated double bonds. Cis-9, trans-11 CLA is the most abundant isomer in the diet, with dairy products and ruminant fats being the richest sources. CLA has been reported to induce potentially favourable effects on body composition, carcinogenesis, atherogenesis, glucose tolerance and immune function. Most of these observations have been made in animal and cell models. The bioactive isomers are believed to be cis-9, trans-11 and trans-10, cis 12 CLA. 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 Ag^ HPLC. The cis-9, trans11 CLA content ranged from 1.93 mg/g lipid (mild cheddar) to 7.32 mg/g lipid (processed cheese) in cheeses, from 0.87 mg/g lipid (ice cream) to 3.71 mg/g lipid (double cream) in dairy products and from 2.88 mg/g lipid (Swedish meatballs) to 6.00 mg/g lipid (minced lamb) in meat products. The trans-10, cis-12 CLA isomer was negligible or not detected in the food samples examined. To provide information about dietary CLA intakes in the UK, the daily intake of CLA was estimated in a cohort of 18 healthy male and female volunteers with normal BMI, using a 7-day weighed-intake food diary. The information from weighed-intake diaries combined with the CLA isomer contents of the foodstuffs was used to gain an estimate of the daily intake of the cis-9, trans-11 CLA isomer. The mean daily intake (± s.d.) of cis-9, trans-11 CLA in the cohort was estimated to be 97.5 ± 73.3 mg/day. The effects of supplementation of 3.75g/day CLA (60:40, trans-10, cis-12 CLA : cis-9, trans-11 CLA) or placebo for 6 weeks on body fat, lean mass, lipid metabolism, glucose tolerance ' and oxidative stress in 25 overweight human volunteers were investigated. CLA had no significant effect on BMI, weight, body fat mass and lean body mass. There were no significant changes in cardiovascular risk factors such as plasma, LDL and HDL cholesterol, plasma glucose and insulin. Also, no antioxidant or pro-oxidant effects of CLA were observed and no adverse side effects of CLA were detected in this study. The results suggest that the daily intake of CLA in the UK is lower than in many other countries and supplementation with 3.75g/day CLA does not induce beneficial effects on body composition and lipid metabolism in overweight individuals.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available