Cell membranes are made primarily of fatty molecules called phospholipids.  Certain kinds of oils called omega-3s and omega-6s are used to create the phospholipids in cell membranes.  Your body needs these oil because it can’t produce them itself.  You can only find these oils through what you eat.  As much as 90 percent of us are deficient in these essential fatty acids.  If you aren’t getting these then your cells use whatever raw materials they can find.  It then tries to find these materials in other places like margarine, vegetable shortening, baked goods and breakfast cereals, saturated fats from meat and dairy products and trans-fatty acids in processed salad and cooking oils. 

Because they are the ones your body can use the membrane and the entire cell begins to malfunction.  When a cell membrane tries to build itself from hydrogenated oils it impairs the the ability of the cell to get oxygen and when they are deprived of oxygen the cells become cancerous.  It seems we just are not informed about how important it is to have these oils in our bodies.  Maybe because of price or laziness food manufacturers substitute less expensive kinds of substances such as margarine, vegetable shortening and supermarket oils.