On November 7th, the FDA announced that it will remove partially hydrogenated oils from the GRAS list (Generally Regarded As Safe). These oils contain trans-fats. The agency has concluded that the voluntary replacement of such fats has not progressed far enough to adequately protect Americans from the negative cardiac health dangers that they pose. This is a good, if seriously belated, decision. It is worth looking back at the history of this food ingredient to see how we came to be eating trans-fats in the first place and what role food labeling (mandatory and marketing) played in that story.
The Origins Of The Low Fat Diet Push
In the 1960s, medical and public health officials became alarmed at the high rates of cardiac-related sickness and deaths in the American population. A correlation was found with high-fat diets and soon there was widespread advice to avoid two particular categories of fat – cholesterol and saturated fats. In retrospect this was a severe over-simplification and a demonstration that correlation does not mean causation. Unfortunately a “low fat diet” caught on as “the answer” with the public and with food marketers. More and more food products entered the market with voluntary labels such as “Low Fat,” “Cholesterol-Free,” “Zero Fat,” and “Low in Saturated Fat." This trend didn’t turn out to be health-promoting. In many foods with lowered fat content, additional sugar was added to make it more palatable. For many years, eggs were demonized because of their cholesterol content when in fact they are an excellent and reasonably priced protein source. All the decades of focus on avoiding fats or certain fats did nothing to stem the obesity epidemic, and reductions we do see in heart attacks and strokes are thus probably linked to other factors.
How Misguided Food Labeling Led To Our Consumption Of Trans-Fats
When the negative focus on fats began, animal fats were major sources of cholesterol and saturated fat in our diets (butter, lard, bacon fat). Tropical oils, such as palm and coconut, were additional sources of saturated fats. The pressure to find alternatives to these oils coincided with an increasingly abundant supply of oil from the domestic soybean crop. Soybeans were a minor US crop before World War II, but by the 1970s they had become the major source of protein for animal feeds. A soybean contains ~20% oil and so it rapidly became the lowest-cost oil in the American food supply.
There are, however, issues with soybean oil. It has properties that make it unsuitable as a simple substitute for animal and tropical fats in various applications (if you are interested there is a short course on the chemistry of oils and fats at the end of this post). It couldn’t be used to make a substitute for stick butter because it was liquid at room temperature. Soybean oil was also poorly suited for deep fat frying applications because it didn’t have the necessary “fry life” to fit in the burgeoning fast-food industry of that time. After a relatively short period of high temperature cooking, it would develop off-tastes. In other products it tended to turn rancid faster that other alternatives.
Food scientists had earlier developed “partial hydrogenation," a process through which most of those issues could be addressed (hydrogenated oils began to be sold early in the 20th century). Hydrogenation allowed food companies to turn soybean oil into margarine and then to market it against butter as a perceived healthier option. In the anti-fat environment, oil processors could sell partially hydrogenated oil to the fast food industry, which then promoted the supposed health advantages of their switch to “vegetable oil.” The converted oils were also extensively marketed in products with the marketing claim, “No Tropical Oils.” This was somewhat of an intended health claim, and also a means of competing with the low cost imported oils from palm and coconut. The hydrogenated oil also had some unique properties which were particularly useful for certain baked goods.
Between low cost and these positive-sounding messages, hydrogenated soybean oil found its way into a host of foods in the US diet. When mandatory nutrient content labeling was established in 1990, Congress failed to fund the education component envisioned in the bill. Thus, the official "back label" only served to further propel the sales of various fat-avoidance products and trans-fats, and did nothing to stem the disinformation on the front, marketing-oriented labels.
Early on, the substitutions being made by these commercial entities were done with confidence that they were a good thing. Unfortunately, that was not true.
The Solution Becomes The Problem
Unfortunately, during the hydrogenation process “trans” versions of certain fats are generated. The term trans has to do with a specific chemical configuration in the fat molecule. In most oils and fats that configuration is generally of the “cis” configuration and rarely the “trans” (again, more details below). It was this subtle difference which was later found to change the way that these fats functioned in our bodies. Most of the fat we eat is simply converted to energy, but some is incorporated in the membranes that surround each of our cells. Some of the fat can also end up in plaque deposited in our veins and arteries. The health issues for trans-fats played out importantly in those functions.
In retrospect, Americans would have been much better served in terms of flavor and health if they had stuck with the animal fats and tropical oils instead of hydrogenated oils (French fries have never been as delicious as when they were cooked in beef tallow!)
Eventually, evidence began to emerge that trans-fats were problematic for human health when consumed in larger quantities. This only very slowly built up to the point where regulators raised red flags and began to require trans-fat labeling in 2006. Many food companies shifted away from trans-fats and to market foods as having "zero transfat." Now the FDA is finally moving to fully eliminate an undesirable ingredient which became common because of earlier labeling trends.
What Should We Learn From This?
So, did we learn from the low fat marketing experience? Seemingly not much. Instead we have continued down the path of magical thinking about food. We go through fad after fad about what single bad actor ingredient to avoid or what magical good component to eat, somehow believing that these simplistic formulas can put us on the path to health. The press, various celebrities and "experts" are often guilty of over-selling such ideas as they emerge incompletely formed from the fields of nutrition or medicine. Well-meaning or simply opportunistic food marketers are then more than willing to follow or even promote each fad. I call that "the marketing of non-existance." We continue to be sold new non-existence options such as “Low Carb,” “no High Fructose Corn Syrup,” “Gluten-Free,” and “non-GMO.” These are dietary strategies based on the mindset that foods are something to be feared or at least viewed with suspicion.
These fads distract us from the fundamental healthy diet principles of moderation and diversity. They distract us from the fact that the most dramatic way that most Americans could improve their health prospects would be to consume more fruits and vegetables. Perhaps its time to start buying what we eat for what it is as a whole food, not for what it is not.
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A Short Course About Oils And Fats
Fats and oils are similar with fats being solids at room temperature and oils being liquid. In both cases they consist of triglycerides - three "fatty acids" connected to a glycerol backbone.
What makes the various fats and oils different from one another is what kind of fatty acids they contain.Fatty acids are chains of carbon atoms with a polar carbonyl group at one end. They differ in the length of the chain and in how many double bonds there are between the carbons.
As shown above, the dominant fatty acid in animal fats is stearic acid with 18 carbons and no double bonds (saturated). Oleic acid which is a major component of olive oil or modern Canola and Sunflower oil also has 18 carbons, but has one double bond (mono-unsaturated). Linolenic acid was one of the problematic components of soybean oil which needed to be fixed by partial hydrogenation. It has 18 carbons and three double bonds (poly-unsaturated). "Tropical oils" are generally shorter chained - Palm oil has mostly 14 carbon amino acids and coconut oil has mostly chains of 12 carbons.
The cis- and trans- fats differ in the orientation of the hydrogen atoms (white) attached to the carbon atoms (black) that are connected by a double bond. The normal cis- configuration has both hydrogens on the same side of the chain. The trans- configuration has the hydrogens on the opposite side of the chain and this gives the fatty acid a different bend and influences its fluid properties when it is part of a membrane. There are some natural trans-fats, particularly in meat and milk from ruminants because rumen bacteria convert unsaturated fats to saturated forms, going through some trans- intermediates along the way. There are actually health benefits associated with the production of Conjugated Linoleic Acid (CLA) in this process.