Sources alimentaires et consommation estimée de CLA

Abstract

The term “conjugated linoleic acid” (CLA) describes a group of geometrical and positional isomers of linoleic acid (18 : 2 9cis 12cis) with double bonds in conjugated position. These isomers are the 18 : 2 8trans 10cis, 18 : 2 9cis 11trans, 18 : 2 10trans 12cis and 18 : 2 11cis 13trans. In human diet, the fats from ruminants are the natural source of these fatty acids (milk, meat…). CLAs is produced by the rumen anaerobic bacteria metabolism of linoleic fatty acid, the 18 : 2 9cis 11trans being the predominant isomer (up to 90% of total CLAs), and named for that reason “rumenic acid”. The CLA richest food is milk (2 - 40 mg/g of fat, depending on the animal feed), as well as butter, dairy products, followed by meat of ruminants. Vegetable oils and margarine contain only small amounts of CLAs (0 - 0.5 mg/g), originating from technological processes. Some significant quantities of CLAs are found in human breast milk, depending on women dietary habits (from 1.9 to 11.2 mg/g). The human consumption levels of CLAs have been estimated in different countries. With food questionnaires of the “3-7 days recall” or “semi-quantitative frequency” types, the population consumption has been estimated between 20 and 500 mg per day, with higher levels in men than in women. In Australia, the dietary intake may reach in some cases 1.5 g/day.

Keywords

• conjugated linoleic acid
• dairy products
• ruminants
• vegetable oils
• margarines
• baby formula and food
• daily intake