What intervention led to a significant LDL reduction in the Portfolio Diet Study?

The Portfolio Diet, which focuses on consuming foods that are specifically known to lower LDL (low-density lipoprotein) cholesterol, played a central role in the study's findings. This diet includes a combination of foods such as nuts, soy protein, oats, barley, fruits, and vegetables, all of which contribute to reducing cholesterol levels through various mechanisms. The dietary components in the Portfolio Diet work by increasing soluble fiber intake, reducing saturated fat consumption, and introducing plant sterols, all of which effectively lower LDL cholesterol.

In contrast, regular exercise, while beneficial for overall cardiovascular health, may not have as direct an impact on LDL reduction as dietary changes. Medication with lovastatin is an approach that can lower cholesterol but was not the intervention being tested in this particular study. The high-fat diet would likely conflict with the principles of cholesterol management; typically, diets that are lower in saturated fat and trans fats are recommended for reducing LDL levels. Thus, the Portfolio Diet with its emphasis on cholesterol-lowering foods stands out as the significant intervention leading to the LDL reduction observed in the study.