Lower Efficacy in the Utilization of Dietary ALA as Compared to Preformed EPA + DHA on Long Chain n-3 PUFA Levels in Rats

We made a comparative analysis of the uptake,
tissue deposition and conversion of dietary a-linolenic acid
(ALA) to its long chain metabolites eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA) with preformed
EPA ? DHA. Diets containing linseed oil [with ALA at
*2.5 (4 g/kg diet), 5 (8 g/kg diet), 10 (16 g/kg diet), 25%
(40 g/kg diet)] or fish oil [with EPA ? DHA at *1
(1.65 g/kg diet), 2.5 (4.12 g/kg diet), 5% (8.25 g/kg diet)] or
groundnut oil without n-3 polyunsaturated fatty acids (n-3
PUFA) were fed to rats for 60 days. ALA and EPA ? DHA
in serum, liver, heart and brain increased with increments in
the dietary ALA level. When preformed EPA ? DHA were
fed, the tissue EPA ? DHA increased significantly compared
to those given ALA. Normalized values from dietary
n-3 PUFA to tissue EPA ? DHA indicated that 100 mg of
dietary ALA lead to accumulation of EPA ? DHA at 2.04,
0.70, 1.91 and 1.64% of total fatty acids respectively in liver,
heart, brain and serum. Similarly 100 mg of preformed
dietary EPA ? DHA resulted in 25.4, 23.8, 15.9 and 14.9%
of total fatty acids in liver, heart, brain and serum respectively.
To maintain a given level of EPA ? DHA, the dietary
ALA required is 12.5, 33.5, 8.3 and 9.1 times higher than the
dietary EPA ? DHA for liver, heart, brain and serum
respectively. Hence the efficacy of precursor ALA is lower
compared to preformed EPA ? DHAin elevating serum and
tissue long chain n-3 PUFA levels.