The highest-profile study on the Portfolio diet was published in 2003 by Jenkins, et al., in the Journal of the American Medical Association. In this randomized, controlled clinical study, 46 healthy hyperlipidemic adults followed a diet that was low in saturated fat and included plant sterols and viscous fibers, as recommended by the Adult Treatment Panel II of the National Cholesterol Education Program; the diet also was high in soy and nuts, as supported by the American Heart Association. The study was divided about evenly between males and females, and the participants were split into three groups. The control group ate a diet very low in saturated fat, based on milled whole-wheat cereals and low-fat dairy foods; another segment ate the same diet plus Lovastatin, (20mg/d); and the last group, the Portfolio diet group, ate a diet high in plant sterols (1.0g/1,000Kcal), soy protein (21g/1,000Kcal), viscous fibers (9.8g/1,000 Kcal), and almonds (14g/1,000Kcal).
The decreases in low-density lipoprotein (LDL) were as follows: the control group experienced an 8% decrease; the Lovastatin/low-fat diet group had a 30.9% decrease; and the Portfolio diet group had a 28.6% decrease. The reductions in C-reactive protein were 10.0% for the control group, 33.3% for the Lovastatin group, and 28.2% for the Portfolio dieters. From a statistical standpoint, there were no differences between the Lovastatin and the dietary portfolio group changes, meaning the Portfolio diet was found to be as effective as the pharmaceutical regimen for controlling cholesterol.