Doubling saturated fat in diet does not increase saturated fat in blood

[Northerner]

Doubling saturated fat in the diet does not drive up total levels of saturated fat in the blood, according to a controlled diet study. Increasing levels of carbohydrates in the study diet promoted a steady increase in the blood of a fatty acid linked to higher risk for diabetes and heart disease.

http://www.sciencedaily.com/releases/2014/11/141121151104.htm

I wonder why/how this was never discovered before? 🙄