Mediterranean diet uses a lot of oil. Healthy oil like olive oil, but oil none the less. The British people were the healthiest they had ever been during the rationing phase. And they were rationed margarine, because butter and animal fats were heavily restricted. So unless ingredients changed over time, something is not adding up. Dairy producers have always been against margarine and it has nothing to do with people's health. Otherwise they would stop selling dairy products to consume. Something "healthier" doesn't make it healthy.
Ingredients in margarine did change over time, and they did drastically. Originally margarine was made from a combination of animal fat, vegetable fat and water(all found in nature and present to different extent in the diet). But over time, exactly during the war and the rationing in US and UK, they switched to hydrogenated vegetable oils - which are chemically modified fats, basically nonexistent in nature. And around this time the consumption of margarine exploded. So for the past 70 years people have been consuming huge amounts of fats that their body cannot metabolize, no wonder this has it's effect over time.
