http://news.bbc.co.uk/2/hi/health/6036409.stm
A study that compared the health benefits of walnuts and olive oil "demonstrates that the protective fat from walnuts actually undoes some of the detrimental effects of a high-saturated-fat diet, whereas a neutral fat, such as olive oil, does not have as much protective ability."
Tests showed that both the olive oil and the walnuts helped to reduce the sudden onset of harmful inflammation and oxidation in arteries that follows a meal high in saturated fat.
Over time, this is thought to cause the arteries to start to harden - and increase the risk of heart disease and stroke.
However, unlike olive oil, adding walnuts also helped preserve the elasticity and flexibility of the arteries, regardless of cholesterol level.
You can't eat whatever you want and scarf some nuts to compensate, but walnuts should definitely be a part of a healthy, whole foods diet. Good calories, good fats!!!