The Effect of Triglyceride Positional Distribution on Fatty Acid Absorption in Rats

BACKGROUND: Human milk contains palmitic acid predominantly in the triglyceride sn-2 position, and differs from the palmitic acid positional distribution found in most infant formulas (predominantly positions sn-1 and sn-3). Following lipolysis by pancreatic lipase, 2-monoglycerides and free fatty acids are produced. All 2-monoglycerides are well absorbed, including 2-monopalmitin, thus providing one reason for the efficient absorption of palmitic acid in breast-fed infants. If infants are fed fat blends with palmitic acid located in the sn-1 and sn-3 positions, the resulting free fatty acids may form poorly absorbed calcium soaps. Therefore, many infant formulas contain only modest levels of palmitic acid. METHODS: Fat absorption studies were conducted in rats with preparations containing various amounts of palmitic acid in the triglyceride sn-2 position. Determining total fat absorption, specific fatty acid absorption, and the presence of calcium-fatty acid soaps. RESULTS: Betapol, a new triacylglycerol, similar to human milk in its palmitic acid content and positional distribution, demonstrated excellent absorption characteristics compared to fat blends derived from either palm olein or oleo (similar in fatty acid profile to Betapol, but with most palmitic acid in the sn-1 and sn-3 positions). A five-point dose response was used to further evaluate the relationship of positional distribution and fat loss. Palmitic acid excretion and fecal fatty acid soaps were negatively correlated to the presence of palmitic acid in the sn-2 position. CONCLUSION: These studies provide evidence that palmitic acid can be efficiently absorbed, avoiding fatty soap formation of it is present in the sn-2 position.