[Nutritional correction of an excess of unsaturated fatty acids in the body lipids of the growing rat].

The use of hydrogenated coconut oil as a putative substance for correcting an excess of unsaturated fatty acids in reserve lipids was tested in growing rats. Young rats with a live weight of about 70 g were given diet A including 4% of sunflower oil which very rapidly created a triglyceride store containing 25 to 30% of linoleic acid (18:2 n-6). At different weights (200, 300 and 350 g), diet A was replaced by diet B containing 15% of hydrogenated coconut oil so that there was the same number of animals in each group. All the rats were killed at 400 g, and diet-A and B were compared as to final fatty acid composition of body lipids (i.e. values taken all during growth from 70 to 400 g). Hydrogenated coconut oil was a very effective substance for rapidly decreasing levels of reserve lipid linoleic acid and for increasing triglyceride melting-point. The impact on the decrease in total unsaturated fatty acid concentrations was more marked the earlier the diet was replaced. However, the latest replacements (at 300 and 350 g) still permitted 70 and 50%, respectively, of the maximal effect observed in rats eating diet B from 70 g. The present experiment shows that when coconut oil was introduced in the diet over a period corresponding to the last one-eight of total body growth in rat, the final concentrations of unsaturated fatty acids could still be considerably reduced, particularly that of linoleic acid. In the same way, there was increasing esterification of myristic acid (14:0), and especially of lauric acid (12:0), which appeared preferentially in sn-1 and sn-3 positions in triglycerides. This esterification of medium-chain fatty acids led to a modification in the mode of other fatty acid distribution. Analysis of liver phospholipids showed that when diet A was replaced above 200 g by diet B, there was no biochemical evidence of any deficiency of essential fatty acids of the n-6 series.