Objective: To evaluate the published clinical data on the physiologic effects of using palm oil and its low melting fraction, palm olein (PO) as a dominant lipid source in the fat blend in infant formulas.
Design: A systematic search of Medline and the Cochrane Database of Systematic Reviews was performed to retrieve studies comparing infants who received infant formulas containing PO with those who received infant formulas without PO or which contained synthetic triacylglyceride as a source of palmitic acid. Outcomes of interest include intestinal fractional absorption of fat, palmitic acid and calcium; and bone mass. The effect size for each dependent variable in each published study was obtained by standardizing based on the difference in means between non-PO and PO group with respect to the standard deviation of the PO group. Trend analysis of the outcome of interest was performed when 3 or more between group comparisons were available. The comparison of effect size across different studies was based on all available data and includes results that showed no significant difference between infants fed PO or non-PO study formulas in the outcomes of interest.
Results: Nine publications were identified with non-PO and PO comparison groups. The gestational ages of infants in the published studies were between 28 to 42 weeks and postnatal ages were birth to 192 days at study onset. Within each published study, there was some variability in the effect size between non-PO and PO groups. The standardized results were consistently significantly (p < 0.05) positive in favor of the feeding with non-PO formulas with respect to increased intestinal fractional absorption of fat, palmitic acid and calcium. The latter two variables were significantly different by at least 0.6 SD. Bone mass measured as total body bone mineral content was significantly higher in the non-PO group by at least 0.3 SD.
Conclusion: The use of PO in infant formulas to match the human milk content of palmitic acid has unintended physiological consequences including diminished intestinal absorption of fat, palmitic acid and calcium and lower bone mass. The avoidance of PO or its substitution with synthetic triacylglyceride in infant formulas can prevent this detrimental effect.