Some years ago margarine was made from vegetable oil hardened by a process called partial hydrogenation. The process involved bubbling hydrogen through vegetable oil with nickel shavings added as a catalyst, in order to force hydrogen atoms into the fat molecules to artificially saturate them so like natural saturated fats they set solid instead of liquid. Some of the fat molecules though are partially hydrogenated and the usually C shaped cis bend is forced into a Z shaped trans bend. This chemically altered trans fat does not occur in nature. Studies have since shown that consuming trans fats causes a marked increase in the risk of heart disease.
By the way you can still find trans / hydrogenated fats in our food – have you ever considered how they get peanut butter to stop separating and have a nice solid consistency? Or how you keep meusli bars from going rancid? Partially hydrogenated fats!
In order to remove dangerous trans fats from margarine, a process is used called interesterification is now used. Since learning of this process I’ve done a little research to find out how this works and if these new fats are likely to cause any health problems.
So here is how interesterification works. Take an oil molecule, called a triglyceride. The structure of a triglyceride is 3 long fatty acid strands (hence tri) joined at one end by a glycerol backbone. Chemicals are used to snip the fatty acid strands off the backbone. They are then mixed with chemically saturated oils (fully hydrogenated oil) and reattached to the backbone in groups of three in an order that simply does not occur in nature. True – there are no trans fats, the nasties linked to heart disease. Instead we have a new type of chemically constructed fat. Studies have been done on this new fat and the evidence is mixed. Some studies show it does not cause an increase in cholesterol like trans fats. However others studies show this new interesterified fat increased blood sugar by 20% in just one month, and greatly increased insulin resistance. It also decreased HDL and increased LDL like trans fats do. This is not good for those of you who may be prone to diabetes, heart disease or weight gain. It will only increase your problems. Barry Sears says “I consider this type of new trans-fat free fat to be far more dangerous than standard trans-fat derivatives.”
So my recommendation is – because they are so unnatural and not proven safe – AVOID MARGARINES!
What should you use instead?
Do what the Spanish do – drizzle or spray olive oil on your bread (of course I don’t actually recommend eating bread) or use a small amount of butter.
You could also make your own spread by softening butter and whisking in olive or macadamia nut oil until you get a balance you like (about 1/2 butter to 1/2 oil)