But, butter isn't necessarily the healthier alternative. While butter and Margarine have similar caloric values, butter is made from milk fat and is generally is much higher than margarine in saturated fat, which is also known to be detrimental to heart health. Margarine contains small amounts of polyunsaturated and monounsaturated fats, which are generally considered healthier than saturated. According to a recent study published in the Journal of the American Medical Association, switching from butter to margarine can greatly reduce blood cholesterol levels. Further, not all margarine is created equal. Many brands have developed semi-solid spreads without hydrogenation - and thus, no trans-fat. Most brands that are trans-fat free proudly and prominently state so on their packaging.
The butter versus margarine debate often comes down to the "naturalness" of each product. Margarine is indeed a durable foodstuff that can survive outside refrigeration without spoiling. However, its durability is not because margarine is chemically similar to plastic, as the letter above asserts. Rather, margarine is made from vegetable oils (corn, canola, olive, etc.), which are less susceptible to bacteria and fungi than dairy fats.
It is not true that margarine is "but ONE MOLECULE from being PLASTIC," and, even if it was, this doesn't mean that eating margarine is like eating plastic (though some would argue it tastes like it). Many items in nature are chemically similar to one another, but that doesn't make them similar in appearance or effect. It's not the molecules that a substance is made of that defines it, but rather how those molecules are arranged. Both butter and margarine contain fats, which are basically groupings of the elements carbon, hydrogen and oxygen. The difference is how those atoms are bonded together. (Naturally occurring fatty acids generally have one "cis" orientation, meaning both hydrogen atoms are on the same side as the carbon atoms. Trans-fatty acids, logically, have a "trans" orientation, meaning that at least one hydrogen atom is opposite the carbons. Essentially, the molecules making up both butter and margarine contain the same atoms, just in different configurations. Margarine has much more in common chemically with butter than it does plastic.