Healthy Fatty Acids in Transition

Overview

Diacylglycerol (DAG) is a molecule that consists of two fatty acid chains bound by ester links to a glycerol molecule, in the form of 1,2 and 1,3 structural isomers. Approximately 10% of the edible oils on today's market are comprised from DAG. DAG oil has a similar taste, appearance, and fatty acid composition as conventional triacylglycerol oil (TAG; consists of 3 fatty acids chains bound to a glycerol molecule), yet recent studies suggest that due to its different chemical structure, DAG oil may induce cardiovascular (CV) benefits. Specifically, human studies in the United States (US) and Japan have shown that long-term consumption of a diet containing DAG oil enhances loss of body weight and body fat compared with TAG oil of similar fatty acid composition. In postprandial studies, serum triglycerides (TG) and remnant like particle cholesterol concentrations, have shown to be lower following ingestion of DAG-enriched oil compared to conventional dietary oil (e.g., soybean, corn), or TAG oil. Therefore, DAG oil appears to be effective for preventing postprandial hyperlipidemia, which is a risk factor for arteriosclerosis. The hypothesis that the investigators propose in this pilot study is that intake of DAG oil, compared to TAG oil will result in a lower LDL-C, and lower LDL-C/HDL-C ratio, as well as a reduction in TG levels. Given the significance of such findings, if confirmed, the investigators will evaluate other important clinical biomarkers for chronic disease (CV Disease, type 2 diabetes, metabolic syndrome), such as insulin sensitivity and inflammation \[as determined by C-reactive protein (CRP), interleukin (IL)-1, IL-6 \& tumor necrosis factor-alpha (TNF-α)\], which also may be beneficially affected by consumption of the palm DAG oil. During the pilot study, the investigators will reserve serum/plasma samples so that these additional assays may be run upon approval of the modification.

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.