Effect of dietary linoleic/alpha-linolenic acid ratio on growth and visual function of term infants
Jensen, C.L., Prager, T.C., Fraley, J.K., Chen, H., Anderson, R.E., and Heird, W.C. 1997. J Pediatr. 131:200-209.
The endogenous synthesis of DHA and AA in preterm infants may not be adequate to maintain lipid levels of these fatty acids comparable to those of breast-fed infants, and these levels are influenced by both ALA and LA intake. The present study in normal term infants studied the effect of ALA intake (or the dietary LA: ALA ratio) on growth and visual function. Infants received formulas with approximately 16% total fatty acids as LA and 0.4%, 1.0%, 1.7%, or 3.2% of fatty acids as ALA (thus supplying a ratio of LA:ALA of 44, 18.2, 9.7, and 4.8) for the first four months of life. Body weights, fatty acid patterns of plasma and erythrocyte lipids and visual evoked responses of infants were determined. Higher ALA intake resulted in higher DHA levels, and higher LA resulted in higher AA levels. The higher DHA content in plasma and erythrocyte phospholipids seen in those infants with the highest ALA intake, did not correlate with any obvious benefit with respect to visual function, as assessed by transient visual evoked responses. The highest intake of ALA was correlated with a lower mean weight, although there was no significant differences in other body measurements such as length, head circumference or armfold thickness, which may be related to a lower rate of fat deposition. Lower rates of weight gain in preterm infants have previously been correlated with fish oil high in eicosapentaenoic acid (EPA), and tissue content of long-chain polyunsaturated omega-6 and omega-3 fatty acids has been shown to play a regulatory role both in the expression of genes for glycolytic and lipogenic enzymes, as well as in insulin sensitivity. The authors conclude that until the apparent effects of ALA intake, or the dietary LA: ALA ratio, on weight gain of infants is better understood, it may be wise not to adopt the lower LA: ALA ratios recommended for infant formulas by a number of organizations and advisory groups.