'Good fat,' low cholesterol, may not be so good after all

(CNN) - Diets rich in vegetable oils and low in saturated fat might not be all they are cracked up to be in terms of heart health, according to new research.

Just about every diet recommends reducing saturated fats, such as butter and cheese, and replacing them with unsaturated fats, such as vegetable oil and fatty fish. The 2015 dietary guidelines advise limiting saturated fats to no more than 10% of daily calories.

There have been only a few studies comparing these two types of fat head-to-head between groups of people eating otherwise similar diets.

In the new study, researchers revisited data from a trial carried out from 1968 to 1973 that involved more than 9,000 adults living in a nursing home or mental hospitals in Minnesota. About half the participants received diets that contained 18.5% saturated fat and 5% unsaturated fat, based on total calories, and the other half got diets that were 9% saturated fat and 13% unsaturated fat. In the unsaturated fat diet, the researchers increased the level of linolenic acid, an omega-6 polyunsaturated fat, found in margarine and oils such as corn and soybean.

Researchers found, not surprisingly, that the group that got the diet rich in linolenic acid had lower cholesterol, by about 13%, than the saturated fat diet group. For this analysis, the researchers only included the 2,403 participants who were on one of the two diets for at least a year. - Read More
'Good fat,' low cholesterol, may not be so good after all

The truth about fats: the good, the bad, and the in-between ...harvard.edu