I don't know when the government first started promoting margarine as healthier than butter. But I do remember that growing up in the 50s my mom had the idea that margarine was healthier, and that's what she bought for the family.  I thought the stuff tasted nasty, particularly  by comparison with butter, which I would get from time to time when we ate at the homes of friends or relatives.  I flatly refused to eat margarine as a kid, and I would eat bread and sandwiches dry.

Whether the government was actually promoting margarine over butter as early as the 1950s, it clearly had taken that path by the 1970s.  This article by Steve Malanga in the City Journal in 2011 recounts some history of government dietary guidelines, and traces government recommendations to replace saturated with unsaturated fat in the diet as least as far back as a Senate Committee chaired by George McGovern in the mid-70s. 

Of course, barely anyone had even heard of "trans fats" back then.  And nobody mentioned that you make margarine have the desirable consistency of butter by bubbling some hydrogen gas through the liquid vegetable oil, during which process hydrogen atoms attach to both sides of the carbon chain in the fat molecule (i.e., trans fats) rather than almost all on the same side as occurs in natural oils (cis fats).  After all, how could that possibly make any difference?  

As recently as the 2000 version of the government's dietary guidelines, they were still recommending substituting unsaturated for saturated fats, with only a passing reference to the concept of trans fats, and even then no clues on how to know what foods had trans fats in them or how to avoid them.

Of course they had no idea what they were doing and their advice was likely at least somewhat dangerous.  Now this past week the FDA has announced new rules that will effectively ban trans fats from the food supply.  The question is, do they have any more idea what they are doing now than they did before?  No, they do not.

Well, over the course of the last 20 years or so, information has come out from various studies indicating potential problems with trans fats.  I say potential problems because as usual with things related to food and nutrition, what we have are poorly controlled epidemiological studies with Relative Risk results way below any acceptable standard for statistical significance, let alone to support government action ordering the people around.  For example, here is the big one on trans fats from the so-called "Nurses Study," Oh, et al., 2004, from the American Journal of Epidemiology.  This study followed some 78,778 U.S. women who were free of cardiovascular disease as of 1980.  How do they know how much trans fats these women consumed?  From questionnaires administered at most once a year based on memory -- not exactly a well-controlled study.   And the Relative Risk for cardiovascular disease based on trans fat intake?  1.33.  Other than the fact that some of the authors were from Harvard and they had done a huge amount of work, this hardly even qualifies as a publishable result.

Now I would say, combined with the fact that the stuff tastes nasty, that 1.33 Relative Risk is a perfectly good reason for a sensible individual to avoid trans fats.  It's also a perfectly good reason for the industry to reduce or eliminate the use of trans fats if they want to.  But for the government to ban trans fats?  Ridiculous.  

Meanwhile, how is it going with the government's campaign against saturated fats, otherwise known as steaks and butter?   I continue to look for actual evidence that saturated fat consumption is associated with an elevated risk of heart disease, and I can't find it.  Can you?  But here is a 1997 study following up on the large Framingham study population, and the conclusion is that margarine eaters have a higher risk of developing heart disease than butter eaters.

I have no doubt that there is an evolutionary reason why butter tastes much better than industrially-made hydrogenated oils.  Can't we just trust our tastebuds? 

The government's ban on trans fats will of necessity drive the food industry to something else, which in all likelihood will be just as unhealthy as the trans fats.  The bureaucrats don't have any idea what they are doing.  Can't they just keep out of this and let the people figure it out?  And how about an apology for the past recommendations?