Bring down people's total cholesterol levels by 11 points (a 5 percent reduction) Reduce harmful LDL cholesterol levels by 10 points (a 7 percent drop). Best effect was seen in those with a starting LDL level above 160 milligrams per deciliter. Shift the ratio of total cholesterol or LDL cholesterol to "good" HDL cholesterol in a favorable direction. Nuts can reduce triglyceride levels by 21 points in people whose triglycerides were too high (150 milligrams per deciliter or higher) but they did not affect triglycerides in people with normal levels. Nuts were best for people with lower body weight, and those who were eating more "Western" diets (meaning more saturated fats and refined carbohydrates).

The nuts consumption and blood cholesterol seemed to be linked inversely with a dose-response relationship, meaning the more nuts people ate, the greater the changes in their cholesterol levels. Different types of nuts had similarly healthful effects on blood fats. Sabate explains that thin and unhealthy eaters benefit more with nuts because others who ate more healthy foods or diets rich in olive oil, fish, whole grains would not show great benefits by adding nuts to their diet. Eating one to two servings of nuts a day benefits most of the people by improving their lipid profile, Sabate added.

Ellen Mason, senior cardiac nurse at the British Heart Foundation agreed with the findings but cautioned against the use of salted nuts. Apart from salted peanuts at the pub, nuts in sugary cereals or the traditional Christmas selection, nuts have been largely lacking in our diets in the UK, she added.

This study received part of the funding from the International Tree Nut Council Nutrition Research and Education Foundation.