Comparative bioavailability of dietary alpha-linolenic and docosahexaenoic acids in the growing rat.
Animal and human studies have indicated that developing mammals fed only alpha-linolenic acid (18:3n-3) have lower docosahexaenoic acid (22:6n-3) content in brain and tissue phospholipids when compared with mammals fed 18:3n-3 plus 22:6n-3. The aim of this study was to test the hypothesis that low bioavailability of dietary 18:3n-3 to be converted to 22:6n-3 could partly explain this difference in fatty acid accretion. For that purpose, we determined the partitioning of dietary 18:3n-3 and 22:6n-3 between total n-3 fatty acid body accumulation, excretion, and disappearance (difference between the intake and the sum of total n-3 fatty acids accumulated and excreted). This was assessed using the quantitative method of whole-body fatty acid balance in growing rats fed the same amount of a 5% fat diet supplying either 18:3n-3 or 22:6n-3 at a level of 0.45% of dietary energy (i.e., 200 mg/100 g diet). We found that 58.9% of the total amount of 18:3n-3 ingested disappeared, 0.4% was excreted in feces, 21.2% accumulated as 18:3n-3 (50% in total fats and 46% in the carcass-skin compartment), and 17.2% accumulated as long-chain derivatives (14% as 22:6n-3 and 3.2% as 20:5n-3 + 22:5n-3). Similar results were obtained from the docosahexaenoate balance (as % of the total amount ingested): disappearance, 64.5%; excretion, 0.5%; total accumulation, 35% with 30.1% as 22:6n-3. Thus, rats fed docosahexaenoate accumulated a twofold higher amount of 22:6n-3, which was mainly deposited in the carcass-skin compartment (68%). Similar proportions of disappearance of dietary 18:3n-3 and 22:6n-3 lead us to speculate that these two n-3 polyunsaturated fatty acids were beta-oxidized in the same amount.
Poumès-Ballihaut
C
C
Institut National de la Recherche Agronomique, Laboratoire de Nutrition et Sécurité Alimentaire, CRJ, Jouy-en-Josas, France. poumes@jouy.inra.fr
Langelier
B
B
Houlier
F
F
Alessandri
J M
JM
Durand
G
G
Latge
C
C
Guesnet
P
P
D000818:Animals; D001682:Biological Availability; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000493:pharmacokinetics*; D004435:Eating; D005231:Fatty Acids, Unsaturated / Q000378:metabolism / Q000493:pharmacokinetics; D005260:Female; D006128:Growth / Q000187:drug effects*; D008297:Male; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D017962:alpha-Linolenic Acid / Q000493:pharmacokinetics*
D005231:Fatty Acids, Unsaturated; D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids