Reassessment of the linoleic acid requirement in presence of alpha linolenic acid in the growing rat

Linoleic acid (LA) and alpha linolenic acid (ALA) are two essential fatty acids involved in physiological processes. We hypothesized that the historic LA requirement has led to an overestimation from the former studies due to the absence of ALA in the diets. Moreover, LA intake is 3 times higher than its historic recommendation in western country diets whereas the literature suggests that, in excess, LA could have some potential deleterious effects in cardiovascular diseases. This work aimed at realizing a LA dose response study in the presence ALA to redefine precisely the LA requirement. Over 14 weeks, offspring of LA deficient female rats consumed different diets composed as followed in energy percent (en percent ) (i) 0 ALA to 0 LA (ii) 0.5 ALA plus increasing doses of LA (0.5 to 1.5en percent ) (n=6/group). Physiological (growth and scaliness) and biochemical (tissue fatty acid compositions and deficiency marker C20:3 n9) parameters have been analyzed. The 0 ALA to 0 LA group has the lowest final body weight gain and developed scaliness on the tail. An exclusive 0.5ALA intake prevented the growth loss but did not cure the scaliness which demand a concomitant 0.5 LA supply to be solved. The C20:3 n9 study has shown a significant and progressive decrease in the tissues correlated with the increase in LA up to 1en percent  (no more benefit for 1.5en percent ). Providing 0.5ALA prevents the loss of growth during a LA deficiency but did not cure the skin problems. A 1 LA intake adds with 0.5 ALA, appears sufficient to restore the physiological and biochemical parameters. In rats, the LA requirement is estimated between 1 and 1.5en percent  when ALA is supplied in the diet. (Authors abstract)