Diets rich in butter, fatty cuts of meat and hard cheeses have often been maligned due to their saturated fat content. A new study published in American Journal of Clinical Nutrition flies in the face of this sacred cow, suggesting that our understanding of saturated fat is fundamentally flawed. Despite the long-held belief that saturated fats block the arteries, the study reveals cholesterol is actually vital for keeping cells healthy.
The researchers contest that when people eliminate unsaturated fats from their diet, they need to eat more products high in polyunsaturated fats to reap the same benefits that come from having a smaller amount of saturated fats.
These substitutes include sunflower oil, walnuts, and fish.
The Norwegian team discovered some saturated fats are naturally present in a wide variety of foods, including breast milk.
The scientists claim that people with high cholesterol who suffer cardiovascular disease may actually have low-grade inflammation and insulin resistance.
“Cholesterol is a critically important molecule for all cells in the body,” said lead author Marit Zinöcke from Bjørknes University College in Oslo.
Zinöcke explained: “A cell is surrounded by a fluid membrane that controls cell function, and the cells depend on the ability to incorporate a certain amount of cholesterol molecules, so that their membranes don’t become too stiff or too fluid.
“The basis of the model is that when saturated fats replace polyunsaturated fats in the diet, less cholesterol is needed in the cell membranes.”
Zinöcke pointed out that the opposite is true when people eat more polyunsaturated fatty acids, which include omega-3 and omega-6 fatty acids.
When polyunsaturated fats enter the cell membranes, they make them more fluid.
Cells can adjust the fluidity of their membranes by pulling in more cholesterol from the bloodstream.
The team believes this is why blood cholesterol levels drop when people eat more polyunsaturated fats.
“Cells need to adjust their membrane fluidity according to changes in their environment, such as the access to different types of fat,” Dankel said.
“This phenomenon is called homeoviscous adaptation, and has been described in both microorganisms, vertebrates and in human skin cells.”
He added: “We argue that this is a critical principle in human physiology. Our cells are normally capable of adjusting their cholesterol content according to changes in dietary fats.
Researcher Karianne Svendsen from the University of Oslo concluded: “Nutrition research often focuses on what changes in the body, but the question of why something, such as the blood cholesterol, changes, is of equal importance.”