So far, this series has examined the state of “knowledge” about saturated fats (Part 1) and omega-6 and omega-3 fatty acids (Part 2). To recap, my conclusions regarding the scientific consensus on these issues are:
1. Saturated fats are probably not as bad as we thought, and they may even be neutral.
2. Too much omega-6 fatty acid, as found in “Western” diets, may be harmful to cardiovascular health.
3. Omega-3 fatty acids may be beneficial to cardiovascular health.
4. And thus polyunsaturated fats are a mixed bag—some may be good, some may be bad.
2. Too much omega-6 fatty acid, as found in “Western” diets, may be harmful to cardiovascular health.
3. Omega-3 fatty acids may be beneficial to cardiovascular health.
4. And thus polyunsaturated fats are a mixed bag—some may be good, some may be bad.
As a result, the recommendations being promulgated by the health “establishment” concerning saturated fats and polyunsaturated fats may be erroneous, misleading, and premature, and are probably subject to change. Soon.
Unless you live under a rock, I’m sure you’ve heard of yet another type of dietary fat that has been in the news for several years: the infamous “trans fat.” First, what is it?
You will recall from the first blog post in this series that fatty acids can have “unsaturated” double bonds between the carbon atoms, meaning that they lack a full complement of hydrogen atoms. If there is only one such double bond, the fatty acid is monounsaturated. If there is more than one, it is polyunsaturated. And if there are no double bonds between the carbons, it is said to be “saturated.” Got it?
Well, trans fats are unsaturated fatty acids—theoretically, they could be either monounsaturated or polyunsaturated. All they require is a double bond between two carbons, with the hydrogen atoms opposed to one another, e.g., on the opposite side of the double bond. (If they are not opposed to each other, that is, if both the hydrogens are on the same side of the double bond, then they are referred to as “cis” rather than “trans”.) That little bit chemistry is important to understanding trans fats.
Next, some history regarding trans fats, which really begins with artificially-produced saturated fats. That’s right, we are back to talking about saturated fats—but in a different vein from that of our discussion in the first blog post of this series.
The history of saturated fat reaches back to lard, tallow, margarine, oleomargarine, shortening, Crisco, hydrogenated soy and cottonseed oil, whale oil, Napoleon Bonaparte . . . wait, what?
Yeah, Napoleon. But not the one you are thinking of (that was Napoleon 1). Here we’re referring to his nephew, Louis-Napoleon Bonaparte or Napoleon III, Ruler of the Second French Empire. In the mid-1800’s, France was apparently having a problem with the cost of butter, so Napoleon III offered a prize (the award of a patent) for someone to come up with a substitute. Well, Hippolyte Mege invented a new concoction he called “oleomargarine” that involved mixing tallow (rendered beef or mutton fat) with skimmed milk. The name was subsequently changed to “margarine.”
Actually, the patented process sounds disgusting—so disgusting that I provide it here to make you glad you weren’t a Parisian who had to eat the stuff:
A fatty body identical in chemical composition with butter is obtained from fresh suet by crushing it between rollers under a stream of water, further washing it and then digesting it with agricultural gastric juice. The fat is extracted, melted, passed through a sieve and poured into boxes to set, after which it is cut into pieces, which are wrapped in cloths and pressed between hot plates. A fatty body is expressed and may be agitated in a closed vessel, cooled, cut up, bleached with acid and washed with water. This purified fat is mixed at animal heat (104°F) with water containing small quantities of bicarbonate of soda, casein of cold milk and mammary tissues along with yellow coloring matter. This is digested, allowed to settle, decanted and cooled and yields a preserved butter. Fresh butter is obtained by agitating the above mixture until a cream is formed, which is then treated as usual to obtain the butter.
A number of large companies started to make this new margarine. By 1877 the dairy industry in New York and Maryland had started to feel the pinch, and about a decade later the Margarine Act of 1886 imposed a 2-cent tax on margarine along with some other fees on manufacturers. But even so, the popularity of margarine continued to grow. (I guess people back then, like me, didn’t enjoy trying to spread hard butter.) More anti-margarine laws were passed, including laws prohibiting yellow margarine. By 1902, 32 states had anti-yellow margarine laws.
So what’s this got to do with trans fats, you are wondering? The answer is that by the turn of the 20th century, margarine was no longer being produced by the Parisian method described above. It was instead being made from vegetable oils, primarily cottonseed oil, by a process known as “hydrogenation” that involved forcing hydrogen gas into the oil under high pressure.
Here’s the deal. Hydrogenation is simply a way to add hydrogen to a fat that has double bonds. So, if you “hydrogenate” a monounsaturated or polyunsaturated fatty acid, you are converting the double bond between the carbons to a single bond and adding hydrogens in its place—the molecule becomes “saturated” with hydrogen atoms, and there is no more double bond. Since saturated fatty acids are solid at room temperature, you can convert a liquid vegetable oil to a solid fat through hydrogenization.
So what these manufacturers did was to take cottonseed oil, hydrogenate it, and make it solid at room temperature. They must have added other components to improve flavor, etc., but the basic idea holds.
The increased use of soybeans for protein during the early 1900’s resulted in increased production of soybean oil. The additional soybean oil, of course, got used to make margarine, as well as other products such as Crisco and Spry (sold in England). These so-called “partially-hydrogenated” vegetable oils were seen as an improvement over naturally-occurring saturated fats because they lasted longer (thus lowering refrigeration costs) and they remained spreadable at room temperature. To top it all off, they were marketed as being healthier. As a result, production increased through the 1960’s and these fats gradually replaced both lard and butter in the Western diet.
But there was a fly in the ointment. Turns out that if the hydrogenation process is incomplete (resulting in a partially-hydrogenated oil), hydrogen atoms can end up on opposite sides of the double carbon bond found in unsaturated fatty acids. These are trans fats (“trans” means “across”). In fact, with incomplete hydrogenation, the “trans” configuration is easier to achieve than the alternative condition, which is a molecule with the hydrogen atoms on the same side of the double bond (which is called a “cis” fat, as described above).
Trans fats were commonly found in polyunsaturated margarines until the mid-2000’s, but they have been banned in Denmark since 2003, in Switzerland since 2008, and in New York City since 2005. With the support of the American Medical Association, in 2003 the FDA issued a regulation requiring manufacturers to list the amount of trans fat on food labels beginning in 2006. By 2007 Crisco had been reformulated to contain “zero grams trans fat.” (In the U.S., less than 0.5 grams per serving can be listed as zero grams on the label.) What’s behind all this?
Well, there is a growing and apparently convincing body of evidence that consumption of trans fats leads to cardiovascular disease. In reviewing the scientific literature for this blog post, I found NO articles that disputed this theory. In fact, the trans fat question seems to be the only dietary fat issue that is not controversial. It would seem that we can put this one in the “settled science” category.
That said, there is one thing about trans fats that is puzzling. Some evidence exists indicating that naturally-occurring trans fats may actually be beneficial to cardiovascular health. So here we go again—some may be good for you, and some may be bad. If it is natural, it is “good,” and if it is synthetic it is “bad.”
Cow’s milk contains between 2% and 5% trans fat. These apparently “good” trans fats include conjugated linoleic acid (CLA) and vaccinic acid. Conjugated linoleic acid is interesting because it can have both “trans” double bonds (hydrogens on opposite sides) and “cis” double bonds (hydrogens on the same side). But for the purposes of food labeling, such a chimera is NOT deemed to be “trans.” Don’t ask me why. Apparently labeling requirements have not yet caught up with the science, or maybe the FDA doesn’t want to confuse consumers by alerting them to the presence of “good” trans fats.
The greatest benefit of CLA seems to be in the area of weight reduction. There are also indications that CLA may also be useful for lowering cholesterol and triglycerides, but obesity control seems to have the largest body of evidence surrounding it. In case you want to increase your intake of CLA, you will be interested to know that kangaroo meat has the highest levels.
Fewer studies have been done on vaccinic acid (another “good” trans fat), also found in milk and butter from ruminants as well as in human milk. But vaccinic acid is converted into CLA in mammals, so I’m not sure what studies on vaccinic acid really say.
So, where are we now?
Synthetic trans fat is bad, but natural trans fat may be good. Saturated fats are either bad or neutral. Omega-6 fatty acids in abundance may be bad, but omega-3 fatty acids are probably good. And the category of polyunsaturated fatty acids is almost meaningless.
And finally, what about monounsaturated fats? We’ll wrap up dietary fat in the next blog post.
Unless you live under a rock, I’m sure you’ve heard of yet another type of dietary fat that has been in the news for several years: the infamous “trans fat.” First, what is it?
You will recall from the first blog post in this series that fatty acids can have “unsaturated” double bonds between the carbon atoms, meaning that they lack a full complement of hydrogen atoms. If there is only one such double bond, the fatty acid is monounsaturated. If there is more than one, it is polyunsaturated. And if there are no double bonds between the carbons, it is said to be “saturated.” Got it?
Well, trans fats are unsaturated fatty acids—theoretically, they could be either monounsaturated or polyunsaturated. All they require is a double bond between two carbons, with the hydrogen atoms opposed to one another, e.g., on the opposite side of the double bond. (If they are not opposed to each other, that is, if both the hydrogens are on the same side of the double bond, then they are referred to as “cis” rather than “trans”.) That little bit chemistry is important to understanding trans fats.
Next, some history regarding trans fats, which really begins with artificially-produced saturated fats. That’s right, we are back to talking about saturated fats—but in a different vein from that of our discussion in the first blog post of this series.
The history of saturated fat reaches back to lard, tallow, margarine, oleomargarine, shortening, Crisco, hydrogenated soy and cottonseed oil, whale oil, Napoleon Bonaparte . . . wait, what?
Yeah, Napoleon. But not the one you are thinking of (that was Napoleon 1). Here we’re referring to his nephew, Louis-Napoleon Bonaparte or Napoleon III, Ruler of the Second French Empire. In the mid-1800’s, France was apparently having a problem with the cost of butter, so Napoleon III offered a prize (the award of a patent) for someone to come up with a substitute. Well, Hippolyte Mege invented a new concoction he called “oleomargarine” that involved mixing tallow (rendered beef or mutton fat) with skimmed milk. The name was subsequently changed to “margarine.”
Actually, the patented process sounds disgusting—so disgusting that I provide it here to make you glad you weren’t a Parisian who had to eat the stuff:
A fatty body identical in chemical composition with butter is obtained from fresh suet by crushing it between rollers under a stream of water, further washing it and then digesting it with agricultural gastric juice. The fat is extracted, melted, passed through a sieve and poured into boxes to set, after which it is cut into pieces, which are wrapped in cloths and pressed between hot plates. A fatty body is expressed and may be agitated in a closed vessel, cooled, cut up, bleached with acid and washed with water. This purified fat is mixed at animal heat (104°F) with water containing small quantities of bicarbonate of soda, casein of cold milk and mammary tissues along with yellow coloring matter. This is digested, allowed to settle, decanted and cooled and yields a preserved butter. Fresh butter is obtained by agitating the above mixture until a cream is formed, which is then treated as usual to obtain the butter.
A number of large companies started to make this new margarine. By 1877 the dairy industry in New York and Maryland had started to feel the pinch, and about a decade later the Margarine Act of 1886 imposed a 2-cent tax on margarine along with some other fees on manufacturers. But even so, the popularity of margarine continued to grow. (I guess people back then, like me, didn’t enjoy trying to spread hard butter.) More anti-margarine laws were passed, including laws prohibiting yellow margarine. By 1902, 32 states had anti-yellow margarine laws.
So what’s this got to do with trans fats, you are wondering? The answer is that by the turn of the 20th century, margarine was no longer being produced by the Parisian method described above. It was instead being made from vegetable oils, primarily cottonseed oil, by a process known as “hydrogenation” that involved forcing hydrogen gas into the oil under high pressure.
Here’s the deal. Hydrogenation is simply a way to add hydrogen to a fat that has double bonds. So, if you “hydrogenate” a monounsaturated or polyunsaturated fatty acid, you are converting the double bond between the carbons to a single bond and adding hydrogens in its place—the molecule becomes “saturated” with hydrogen atoms, and there is no more double bond. Since saturated fatty acids are solid at room temperature, you can convert a liquid vegetable oil to a solid fat through hydrogenization.
So what these manufacturers did was to take cottonseed oil, hydrogenate it, and make it solid at room temperature. They must have added other components to improve flavor, etc., but the basic idea holds.
The increased use of soybeans for protein during the early 1900’s resulted in increased production of soybean oil. The additional soybean oil, of course, got used to make margarine, as well as other products such as Crisco and Spry (sold in England). These so-called “partially-hydrogenated” vegetable oils were seen as an improvement over naturally-occurring saturated fats because they lasted longer (thus lowering refrigeration costs) and they remained spreadable at room temperature. To top it all off, they were marketed as being healthier. As a result, production increased through the 1960’s and these fats gradually replaced both lard and butter in the Western diet.
But there was a fly in the ointment. Turns out that if the hydrogenation process is incomplete (resulting in a partially-hydrogenated oil), hydrogen atoms can end up on opposite sides of the double carbon bond found in unsaturated fatty acids. These are trans fats (“trans” means “across”). In fact, with incomplete hydrogenation, the “trans” configuration is easier to achieve than the alternative condition, which is a molecule with the hydrogen atoms on the same side of the double bond (which is called a “cis” fat, as described above).
Trans fats were commonly found in polyunsaturated margarines until the mid-2000’s, but they have been banned in Denmark since 2003, in Switzerland since 2008, and in New York City since 2005. With the support of the American Medical Association, in 2003 the FDA issued a regulation requiring manufacturers to list the amount of trans fat on food labels beginning in 2006. By 2007 Crisco had been reformulated to contain “zero grams trans fat.” (In the U.S., less than 0.5 grams per serving can be listed as zero grams on the label.) What’s behind all this?
Well, there is a growing and apparently convincing body of evidence that consumption of trans fats leads to cardiovascular disease. In reviewing the scientific literature for this blog post, I found NO articles that disputed this theory. In fact, the trans fat question seems to be the only dietary fat issue that is not controversial. It would seem that we can put this one in the “settled science” category.
That said, there is one thing about trans fats that is puzzling. Some evidence exists indicating that naturally-occurring trans fats may actually be beneficial to cardiovascular health. So here we go again—some may be good for you, and some may be bad. If it is natural, it is “good,” and if it is synthetic it is “bad.”
Cow’s milk contains between 2% and 5% trans fat. These apparently “good” trans fats include conjugated linoleic acid (CLA) and vaccinic acid. Conjugated linoleic acid is interesting because it can have both “trans” double bonds (hydrogens on opposite sides) and “cis” double bonds (hydrogens on the same side). But for the purposes of food labeling, such a chimera is NOT deemed to be “trans.” Don’t ask me why. Apparently labeling requirements have not yet caught up with the science, or maybe the FDA doesn’t want to confuse consumers by alerting them to the presence of “good” trans fats.
The greatest benefit of CLA seems to be in the area of weight reduction. There are also indications that CLA may also be useful for lowering cholesterol and triglycerides, but obesity control seems to have the largest body of evidence surrounding it. In case you want to increase your intake of CLA, you will be interested to know that kangaroo meat has the highest levels.
Fewer studies have been done on vaccinic acid (another “good” trans fat), also found in milk and butter from ruminants as well as in human milk. But vaccinic acid is converted into CLA in mammals, so I’m not sure what studies on vaccinic acid really say.
So, where are we now?
Synthetic trans fat is bad, but natural trans fat may be good. Saturated fats are either bad or neutral. Omega-6 fatty acids in abundance may be bad, but omega-3 fatty acids are probably good. And the category of polyunsaturated fatty acids is almost meaningless.
And finally, what about monounsaturated fats? We’ll wrap up dietary fat in the next blog post.
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