Although the consumption of trans-fatty acids or hydrogenated fat has consistently been shown to elevate concentrations of total and LDL cholesterol, the effects on HDL-c and Lp(a) are inconsistent, especially when the fats were consumed at moderate levels. In addition, little is known about the mechanisms by which trans-fatty acids increase total and LDL cholesterol levels or how they may alter the atherogenecity of lipoprotein subfractions. The study interventions employ commonly used hydrogenated fats with a wide range of trans-fatty acid levels (1.5-9.8 percent). The impact will be assessed within the guidelines currently recommended for individuals with moderately elevated plasma levels for which dietary modification is often the first approach to treatment. The results of the study may lead to improved public health recommendations concerning trans-fatty acid and hydrogenated fat intake.