The team randomly assigned people to eat a Mediterranean diet—which included higher amounts of vegetables, fruits, legumes and whole grains, and low to moderate amounts of fish and poultry—or a still-healthy low-fat diet, which stressed cutting back on sweets, meat, high-fat dairy and processed foods. But those eating the Mediterranean diet were further divided into two groups: People in one group were instructed to have four teaspoons of olive oil as part of their daily diet, and one group asked to have a “fistful” of nuts every day. Cholesterol and other markers were measured at the beginning and end of the one-year study period.
None of the groups had higher HDL levels in the end, but people in the Mediterranean diet groups had improved HDL function, and this was particularly true for those in the olive oil group. The difference was borne out in a few different ways. They had better movement of cholesterol into the liver where it can be broken down or eliminated from the body; better antioxidant protection (whereby HDL prevents LDL from getting oxidized and triggering plaques to develop); and better function of the blood vessels.
Oddly, people in the control group (the low-fat diet) had better LDL and total cholesterol numbers (a good thing), but the anti-inflammatory action of HDL was lower in this group, too, which is not so good.New study: For a Healthy Heart, add a little Olive Oil,