α-Linolenate reduces the dietary requirement for linoleate in the growing rat

Abstract

Background: We hypothesized that due to the absence of a dietary source of omega-3 fatty acids, the essential fatty acid (EFA) deficiency model leads to an overestimate of linoleic acid (LA) requirements.

Methods: over 7wk, young rats consumed an EFA diet containing either 0en% linoleate (0LA) and 0en% α-linolenate (0LNA) or a diet containing 0.5en% LNA plus one of seven levels of added LA (0.12-4.0en%; n=6/group).

Results: Rats consuming the 0LA-0LNA diet had the lowest final body weight, 34-68% lower LA and arachidonate in plasma and liver, 87% lower LA in epididymal fat, and an 8-20 fold higher eicosatrienoate in plasma, liver and muscle lipids. 0.5LNA completely prevented the lower growth and partly prevented the rise in eicosatrienoate seen in the 0LA-0LNA group.

Conclusion: Providing dietary LNA at 0.5 en% reduces the rat's physiological requirement for LA by an estimated factor of at least four (0.5en% instead of 2en%). Since LA requirements in humans are also based on the same flawed model of EFA deficiency, it is plausible that they too have been overestimated and should therefore be reinvestigated.