But, isn’t margarine a product that contains vegetable fats and hence a very healthy fat for us? Well, yes it does, and no it is not. How many times have you heard about margarine being a nice alternative to butter? Let me tell you it is not. But don’t worry, I’m not so famous and disrespectful to ask you about just trusting me. Nobody should. Even more in nutrition affairs, a world of tales, lies and misconceptions.
Brief hitoric context. The USDA convenient pyramid and the fat wars
So much have been said about fats. They have been demonized for a lot of years since Ancel Keys published in 1970 the Seven Countries Study. You have to understand one thing about nutrition at this point : there’s a lot of money at stake. So, following the next years, the USDA (United States Department of Agriculture) seized the opportunity and recommended a high complex carbohydrates-low fat diet. In other words, eat more grain! It’s cheap and we are plenty of it for everyone. And, as final result a few years after, the USDA well known food pyramid was born.
But, without enough scientific background, this pyramid is slowly but surely getting demolished. Fat content in diet is now considered not so relevant, or not relevant at all, preventing cardiovascular diseases. Polyunsaturated fats, like those present in vegetable oils from which margarine is made, have been also usually considered better for the cardiac health than saturated ones. Saturated fat in diet is now being reviewed nevertheless, and there are confronted opinions and interests. Do we know anything about nutrition and what we eat I ask. Well, while not everything is clear as ice about saturated and unsaturated fats, it seems there’s something all scientific community (not the food industry) agrees on: trans fats, also called hydrogenated fats, are bad for health. And margarine, among others like fast food, bakery products and industrial food in general, is very rich in those.
Fats explained in 3 points
That’s ok but: trans, saturated, unsaturated, omega-3…? What are all this therms I hear every time we talk about nutrition and fat? Categories they are. We humans love to categorized. We distribute fats in categories that are related to it’s chemical composition and it’s consequent properties. Lipid is the more generic therm that enclose fats. Fats are just one kind of lipids, composed by 3 fatty acids (combined via glycerol esterefication) to conform a triacylglyceride or TAG (also known as triglyceride: TG).
There are different lipid kinds you have probably heard about, like cholesterol, phospholipids, waxes…but today we are focusing on triglycerides, called just fats from now on.
1. Unsaturated fats
These are the fats that contain double bounds in it’s fatty acids. Fatty acids are composed by long chains of carbon, in which we can find or not this double unions that change its properties. One double bound=monounsaturated. More than one=polyunsaturated. That’s all. Vegetable oils, like the olive oil, are very rich in this fats. Unsaturated fats liquefied at lower temperatures than saturated, and this oils are liquid at ambient temperature: that make sense.
Omega-3, omega-6 (and company) are in fact polyunsaturated fatty acids. The number indicates where the first double bound is positioned in the chain. Nothing more, nothing less. It seems several health implications have been found regarding the proportion of this fatty acids in the diet, concluding that we should ingest more omega-3 constituted fats than we do, specially in occidental diets.
2. Saturated fats
When there’s no double bounds in the carbon chains of any of the fatty acids we have a saturated (hydrogen saturated) fat. These are mainly present in animal sources of food, like bacon, butter, eggs, but also in some vegetables, like coconut. Now, compare butter to oils: this saturated fats solidify easier than the unsaturated.
I’m in position now for explaining what the trans fats are and why margarine is not the polyunsaturated salvation you are looking for. So let’s use all this new concepts.
The devil wears vegetable oil.
3. Trans fats
As I said before, the “classic point of view in nutrition” is that unsaturated fats are better for health than saturated ones. Let’s suppose this is true, even though there’s some controversy lately, as we have already seen. It’s not quite relevant for our intentions. So, if unsaturated fats are better, we should consume more vegetable fats (oils) and less animal fats like butter. Margarine is made of vegetable oils, so…False! Margarine solidifies like butter when you put it in the cooler, right? And what did I said about polyunsaturated oils? They have a low melting point. So, how is it possible to margarine getting this solid appearance? Answer: hydrogenation. A chemical process that saturates partially the double bonds present in the TAG. Saturation equals better solidification, as we have seen in the saturated fats category. But even more, this artificially saturated fats obtained from vegetable oils are cheaper than butter and have better properties like more rancidity resistance and better fluency. Magnifique! That would have said Hippolyte, the french chemist that developed the product in the XIX century (that old margarine is, yes).
Magnifique?…not at all! The configuration of double naturally occurring bounds (the bast majority of them) is called cis. This is better understood by the figure below, so take a look and continue reading. When you hydrogenate unsaturated fats, not every double bond gets saturated. Instead, some of them change to a more stable situation: the trans configuration. There we have our trans or hydrogenated fats. Solid, cheaper, more stable fats used in fast food, snacks, biscuits, and all kind of anything but healthy food. Including margarine.
And what’s about this trans configuration? It happens that this trans TAG are recognized by the body like normal fats, but when our biochemical system try to use the trans fatty acids they malfunction since their properties aren’t equal to those that present only cis bounds.
Do you want more evidences that trans fats aren’t good for you?FDA announcement published in June 2015: FDA Cuts Trans Fat in Processed Foods.
While it’s true that ruminants fats contain small quantities of trans fats, studies like this one have shown that, unlike the industrially originated ones, the impact on health of these fats is negligible. Maybe because of the low concentration of trans fatty acids regarding the industrial alternative. That’s probably why the ruminant natural trans fats are out of the FDA ban.
So, there we go. While there’s debate, and more independent research is needed in nutrition and fats, you’d better not believe commercial adds and always keep skeptic about this issues. Marketing can make the unhealthy healthy at the lobby speed of light.
Do you know about other nutrition myths that remain “in the shadows”? Would you like more nutrition-related posts? Let me know what you think, and see you in the next post.