The 1930s brought an amazing change to the production GRS Ultra Review of margarine when the process of hydrogenation was developed. In the 1950s, it was discovered that the hydrogenation process could be stopped short, resulting in the dreaded partially-hydrogenated oils we know so well today. This process saved money and so became the standard process of making margarine.
Today, margarine continues to outsell butter, probably because it is often half the price of butter and tastier than ever before. When the dangers of transfats came to the surface a few years back, along with their connection to partially-hydrogenated oils, low-fat butter-like spreads became available. These advertise excellent health benefits, with traces of fish oil to provide you with Omega-3 fatty acids. These brands claim to provide the best things for your health since sliced... butter.
So who is right and who is wrong? I'll play devil's advocate here by saying they both are. Of course, butter is butter - apart from the salted and unsalted versions - but there are different kinds of margarine. If you choose to spread "poor man's butter" on your bread, choose those made with sunflower oil, soya, olive oil, or my personal favorite, rapeseed oil - also known as canola oil in the US and Canada. Of course, you can always choose butter, but use it sparingly and as a luxury, since half of it is saturated fat.