Healthy Fatty Acids in Transition

Commonly consumed vegetable fats and oils are comprised predominantly of TAG, and small amounts of DAG and monoacylglycerol. TAG consists of 3 fatty acid ester, whereas diacylglycerol oil has 2 fatty acid esters linked to a glycerol backbone. Recently, Watanabe et al., developed a process by which the ratio of glycerides found in plant oils such as soybean, canola (rapeseed), or corn can be shifted from TAG to DAG, leading to the formation of oil composed largely of DAG. Commercially, DAG oil is produced by esterification of fatty acids derived from natural edible plant oils in the presence of lipase enzyme. Commercially produced vegetable DAG oil contains >80% DAG, <20% TAG, <5% monoacylglycerols, and small amounts of emulsifiers and antioxidants to maintain quality. The main constituent fatty acids of DAG oil are oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids, present as 1,3- and 1,2 (or 2,3)-DAGs in a ratio of 7:3, respectively. These structural differences may be responsible for the purported metabolic effects of DAG compared to TAG oil, DAG oil has fewer fatty acids than TAG, and DAG-oil with a greater proportion of DAG in the sn-1,3 versus sn-1,2 form may be more readily oxidized. Thus, the effects of DAG oil on increasing LDL-C would be expected to be less than TAG oil.