Effects of Supplementation of Formula with Docosahexaenoic Acid, Arachidonic Acid and Linolenic Acid on Brain Fatty Acid Composition in Artificially Reared Rat Pups
Wainwright, P.E., Huang, Y.S., Ward, G.R. AOCS Press, Champaign, Ill:180-1. 89.
Optimal brain development requires specific fatty acids, especially DHA and AA. Tissue levels are a function of dietary levels of n-3 and n-6 PUFA, through a complex relationship. In order to define the complex inter-relationship among the various fatty acids a model that precisely controls the amounts of individual dietary fatty acids to which the developing brain is exposed is required. Additionally, the model used should examine the effects of various dietary manipulations during a period when the mammalian brain is developing rapidly, such as in artificially reared rat pups. The authors studied the effects of supplementation with DHA and AA or with DHA and GLA, while keeping the LA and ALA levels constant. DHA was increased in the brain in both studies. However, supplementation with DHA and AA showed reciprocal effects in that high dietary levels of DHA reduced AA levels and vice versa. The effects from supplementation of DHA and GLA were less clear, although the trend of increased AA as dietary levels of GLA increased was apparent. The large variability in this result may be due, in part, to the low levels of AA and GLA (0.4%), which is within the ranges found in mammalian breast milk. The results of these studies suggest that a high level of DHA during brain development ensures high levels of DHA in the brain, but may lower AA levels. Furthermore, this effect may be lessened by the addition of either dietary AA or GLA. However, the relative efficacy of dietary AA versus GLA, in the presence of high n-3 fatty acids in the developing brain requires a further study that directly compares the two fatty acids, in order to determine if dietary GLA differs from AA in its modulatory effects on AA and DHA levels in tissue.