Function and metabolism
Oxidation, conversion and accumulation
of dietary a-linolenic (18:3 (n-3)
and docosahexaenoic (22:6 (n-3), DHA)
acids in the growing rat
Carine Poumès, Françoise Houlier, Jean-Marc Alessandri,
Georges Durand, Philippe Guesnet
Inra, laboratoire de nutrition et de sécurité alimentaire, Domaine de Vilvert,
78352 Jouy-en-Josas Cedex, France-guesnet@diamant.jouyinra.fr
Carine Poumès is the recipient of a joint grant from the Institut national de la recherche
agronomique (Inra) and Blédina SA, groupe Danone, Villefranche-sur-Saône, France
Abstract
A high β-oxidation rate of a-linolenate (18:3 (n-3) could explain in part
the suboptimal docosahexaenoate (22:6 (n-3) content in blood and brain
lipids in formula-fed infants. To test this hypothesis, we measured the
respective apparent β-oxidation rate of 18:3 (n-3) and 22:6 (n-3) in the
growing rat using the whole body fatty acid balance method. During
a 35-day balance period, rats received a diet containing 5 % of lipids
which supplied 200 mg (per 100 g) of either 18:3 (n-3) or 22:6 (n-3).
Analysing the whole body fatty acid balance showed that 59% of the
amount of 18:3 (n-3) ingested disappeared (apparent β-oxidation), 0.5%
was excreted in the faeces, 21% were accumulated as 18:3 (n-3) (50%
in total fats and 46% in the carcass-skin compartment), and 19%
converted into long-chain fatty acids (with 14% as 22:6 (n-3).
Concerning the docosahexaenoate balance, similar results were noted
(disappearance: 62.5%; excretion 0.5%; total accumulation: 37%,
with 30% as 22:6 (n-3) and 7% as 20:5 (n-3) + 22:5 (n-3). Contrary
to 18:3 (n-3), 22:6 (n-3) was mainly deposited in the carcass-skin
compartment (68%).
Our data demonstrated that the suboptimal 22:6 (n-3) content in formula-fed infants could not result from a higher β-oxidation rate of
18:3 (n-3).
Résumé
Un taux d’oxydation particulièrement élevé de l’acide a-linolénique pourrait être la cause du statut non-optimal en acide docosahexaénoique
(DHA, 22:6 (n-3) des enfants allaités artificiellement. Pour vérifier cette
hypothèse, nous avons mesuré les taux respectifs de β-oxydation apparente du 18:3 (n-3) et du 22:6 (n-3) chez le rat en croissance, en utilisant la méthode du bilan corporel. Pendant les 35 jours d’étude, les
animaux ont reçu un régime alimentaire renfermant 5 % de lipides
qui fournissent 200 mg (pour 100 g) de 18:3 (n-3) ou de 22:6 (n-3).
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Oxidation, conversion and accumulation
of dietary a-linolenic (18:3 (n-3)
and docosahexaenoic (22:6 (n-3), DHA)
acids in the growing rat
Carine Poumès, Françoise Houlier, Jean-Marc Alessandri,
Georges Durand, Philippe Guesnet
Inra, laboratoire de nutrition et de sécurité alimentaire, Domaine de Vilvert,
78352 Jouy-en-Josas Cedex, France-guesnet@diamant.jouyinra.fr
Carine Poumès is the recipient of a joint grant from the Institut national de la recherche
agronomique (Inra) and Blédina SA, groupe Danone, Villefranche-sur-Saône, France
Abstract
A high β-oxidation rate of a-linolenate (18:3 (n-3) could explain in part
the suboptimal docosahexaenoate (22:6 (n-3) content in blood and brain
lipids in formula-fed infants. To test this hypothesis, we measured the
respective apparent β-oxidation rate of 18:3 (n-3) and 22:6 (n-3) in the
growing rat using the whole body fatty acid balance method. During
a 35-day balance period, rats received a diet containing 5 % of lipids
which supplied 200 mg (per 100 g) of either 18:3 (n-3) or 22:6 (n-3).
Analysing the whole body fatty acid balance showed that 59% of the
amount of 18:3 (n-3) ingested disappeared (apparent β-oxidation), 0.5%
was excreted in the faeces, 21% were accumulated as 18:3 (n-3) (50%
in total fats and 46% in the carcass-skin compartment), and 19%
converted into long-chain fatty acids (with 14% as 22:6 (n-3).
Concerning the docosahexaenoate balance, similar results were noted
(disappearance: 62.5%; excretion 0.5%; total accumulation: 37%,
with 30% as 22:6 (n-3) and 7% as 20:5 (n-3) + 22:5 (n-3). Contrary
to 18:3 (n-3), 22:6 (n-3) was mainly deposited in the carcass-skin
compartment (68%).
Our data demonstrated that the suboptimal 22:6 (n-3) content in formula-fed infants could not result from a higher β-oxidation rate of
18:3 (n-3).
Résumé
Un taux d’oxydation particulièrement élevé de l’acide a-linolénique pourrait être la cause du statut non-optimal en acide docosahexaénoique
(DHA, 22:6 (n-3) des enfants allaités artificiellement. Pour vérifier cette
hypothèse, nous avons mesuré les taux respectifs de β-oxydation apparente du 18:3 (n-3) et du 22:6 (n-3) chez le rat en croissance, en utilisant la méthode du bilan corporel. Pendant les 35 jours d’étude, les
animaux ont reçu un régime alimentaire renfermant 5 % de lipides
qui fournissent 200 mg (pour 100 g) de 18:3 (n-3) ou de 22:6 (n-3).
155