THE DIETARY FAT CONUNDRUM--PART 4

The Dietary Fat Conundrum—Part 4

I’m winding down here.  The previous three blog posts can be summarized as follows:

Synthetic trans fat is “bad,” saturated fats are probably “neutral”, omega-6 fatty acids in abundance are probably “bad,” omega-3 fatty acids are “good,” and the category of polyunsaturated fatty acids is probably meaningless. 

I can also add that you should ignore ANY website that purport to make recommendations concerning dietary fat (including this one!).

And here’s why.  Now, you’d think that everything published by the Mayo Clinic would be pretty reliable.  I’d have to put Mayo’s right up there with the “best available information for the general public.”  What this means is that if I were interested in learning about heart valve replacements, I’d certainly consider the Mayo Clinic to be a reputable source of information.  And if I were interested in learning about what I should put in my mouth, they should be pretty reliable on that score too—certainly when compared to websites with titles such as “fitday” or “nutristrategy” or “healthyeating” or “paleohacks” or  “dreamfieldsfoods” or “moonbeameating” . . . . I made that last one up, but it does summarize my sentiments regarding a lot of the dietary information out there.  Just moonbeams.  Wishful thinking straight out of la la land.

Here is a recommendation regarding fat intake copied directly from the Mayo Clinic’s website:

     “All fats are high in calories, so limit serving sizes.”

     “Choose monounsaturated or polyunsaturated fats.  Limit saturated fats and trans fats.”

     “Choose regular soft margarines that list liquid oil as the first ingredient, or choose reduced-calorie margarines made with liquid oil that list water as the first ingredient.”

Well, let’s take a look at this recommendation piece by piece.  Certainly fats are high in calories.  Gram for gram, when compared to protein and carbohydrates, fat has the most.  So, assuming you need to reduce calories, maybe it’s a good idea to “limit serving sizes.”  Next, you’re supposed to eat monounsaturated or polyunsaturated fats.  I presume this is because you’re not supposed to eat saturated fats, and the only kinds left are monounsaturated and polyunsaturated.   Well, this is just plain dogma.  First, the evidence for reducing saturated fats is pretty sketchy (see blog post #1 in this series).  Second, polyunsaturated fats are a grab bag of good and bad fats (see blog post #2 in the series).  So the Mayo Clinic is recommending that you eat fats that a lot of the evidence says are “bad” for you.  What’s with that?  Finally, I guess the reason they are recommending margarine with liquid oil is so that you will know for sure that you’re not consuming saturated fats, which are solid at room temperature.  See previous sentence.

And what about the monounsaturated fat recommendation?   First, monounsaturated fats are fatty acids with only one double bond—hence the “mono” prefix.  Like polyunsaturated fatty acids, they are liquid at room temperature.  There are two common monounsaturated fatty acids: palmitoleic acid and oleic acid.  They are found in meat, milk, nuts, avocados, olive oil and lots of other foods.  Olive oil, for example, is about 75% monounsaturated fat. There is a variety of sunflowers that is 85% mono.  Canola oil is 58% mono.  And even in meat, almost 50% of  the fatty acids are monounsaturated.  Actually, if you look at a food chart, you will find that almost everything we eat contains significant amounts of monounsaturated fats.

So, any recommendation that you increase your intake of monounsaturated fatty acids is almost meaningless—they are everywhere.  In fact, your own body can turn stearic acid (a saturated fat) into oleic acid (a monounsaturated fat)!  Therefore, if you eat a juicy steak, which is already about 50% monounsaturated fatty acid, some of the remaining (saturated) fat could be turned into monounsaturated fat.  So you could get some olive oil equivalents from eating a steak.  How cool is that?

Hmmm.  I wonder if anybody has figured out the percentage of stearic acid that is converted to oleic acid by our bodies?  Oh, yes, I see that they have—in a 1994 study using radioactively labeled palmitic and stearic acid.

This is actually an interesting study.  It involved 7 subjects, young men.  They were fed radioactively-labeled stearic acid and palmitic acid, both saturated fatty acids.  Then, over 24 hours, the researchers watched what happened to these tagged fatty acids.  First, two of the subjects didn’t absorb the palmitic fatty acids at all.  I thought this was strange at first, but apparently fatty acids are absorbed more readily when they are mixed with other triglycerides (the main constituent of fats and oils).  So, this tells us that absorption of fatty acids varies from person to person and depends in part on diet. 

What the researchers found was that the subjects (the ones who were able to absorb the radioactively-labeled fatty acids) converted between 6% and 14% of the stearic acid and between 2.8% and 4.2% of the palmitic acid to monounsaturated fatty acids.   (Not all saturated fatty acids behave similarly, however.)

OK, so, this little study was not earth-shaking, but it supports the statement that a percentage of saturated fatty acids are converted in the human body to oleic acid (again, oleic acid is a monounsaturated fatty acid that makes up about 75% of the fat in olive oil),  with the amount of conversion varying from person to and person and being dependent, to some degree, on diet.

As you may have noticed, we are again kind of circling around to the beginning of the fat story.  We started with saturated fatty acids in the first blog post, and I am still talking about saturated fatty acids in the last one.  Well, I really have no choice, because ALL of the saturated fatty acids can be converted to monounsaturated fatty acids (each of the saturated fatty acids has its own complementary monounsaturated fatty acid).  So it’s impossible to talk about one without the other.

Let me also point out that saturated fatty acids account for between 30% and 40% of total fatty acids in animal tissues, with palmitic acid comprising 15-25% of saturated fatty acids, stearic 10-20%, myristic acid 0.5%-1%, and lauric less than 0.5%.

And let me say something else:  as of 2010, stearic acid appears to have NO effect on cardiovascular disease.  It is neutral—although it may be involved in promoting obesity.  Wonder if olive oil makes you fat?  With all the great things we hear about olive oil, I guess not.

What about palmitic acid (the number one saturated fatty acid)?  Now this is really interesting—it can be converted into a monounsaturated fatty acid (sapienic acid) that has been implicated in the development of acne!   And the story gets even more interesting.    Myristic acid (a saturated fatty acid found in coconut oil and butter) can either be converted into one of the polyunsaturated omega-3 fatty acids, or enhance their formation!  What??  And get this:  in humans, a diet with myristic acid comprising less than 1.2% of energy requirements ENHANCED omega-3 fatty acids (DHA and EPA), while a diet with more than 1.2% DECREASED omega-3 fatty acids!

Okay, I think this is a good place to pause.  What do we know?  Well, saturated fatty acids are not a uniform class—they have different metabolic end points with different effects. Different concentrations in diets may have different, even opposite, results.  All of this supports my conclusion in blog post #1 that the relationship between saturated fatty acids and cardiovascular disease is not settled.  Heck, the right amount of myristic acid may be as good as eating fish oil!

Just for fun, let’s look at the three most common saturated fats individually:

1.             The evidence indicates that STEARIC acid does not cause cardiovascular disease.

2.   I found no evidence that PALMITIC acid has any effect on cardiovascular disease.

3.   I found no evidence that MYRISTIC acid has any effect on cardiovascular disease.

So at present, there appears to be no basis for believing that the top three saturated fatty acids cause harm to the human cardiovascular system.   So what’s left in this class of fatty acids?  Could it be lauric acid (less than 0.5% of animal tissues) that’s causing all the trouble?  No, it has been has been shown to increase HDL (the “good” cholesterol).   So why all the ranting and raving about lowering saturated fat?  I have no idea. 

I should also point out that, of course, we don’t eat saturated fats, or any other fatty acids, in a vacuum.  They come to us as complex mixtures, and who knows how they react with each other.   Maybe two “good” fatty acids make something harmful.  Or vice versa.  I don’t know, and I’d be willing to bet that nobody else does either.  But one thing we do know is that the saturated fat story is not nearly as clear-cut as the Mayo Clinic’s dietary recommendation would lead you to believe.  And besides that, it’s probably just outright WRONG.

Okay, back to monounsaturated fatty acids.  At this point, you can probably guess that we shouldn’t focus on the monos as a uniform class.  The saturated fats aren’t, and neither are the polyunsaturated fats.  So let’s look at some of the monos as individual fatty acids.  First, the most popular one:  oleic acid, named after the olive (genus Olea, get it?).  Who says scientists don’t’ have a sense of poetry!

Certainly olive oil gets a lot of favorable press.  It is central to the “Mediterranean Diet,” and it has been correlated with both fat loss and increased cardiovascular health.  I found almost no information saying that olive oil is bad for you—in fact, just the opposite.   It has been correlated with an increase in the oxidation of many fatty acids—so maybe it helps “burn” other fats.  It has been associated with decreasing LDL (the “bad” cholesterol), increasing HDL, and decreasing blood pressure.  And while there is a small amount of data indicating that olive oil may promote breast cancer, there is also evidence that it may inhibit breast cancer.   So I guess I place oleic acid in the class of one of the “good” monos.  With the breast cancer caveat.

The next most common monounsaturated fatty acid is palmitoleic acid.

Well, in searching  the web for data on palmitoleic acid and found a 2011 editorial.  Great—current literature.  The writer’s only citation was  a 1994 study showing that a diet rich in palmitoleic acid increased LDL (bad cholesterol) and decreased HDL (good cholesterol).  As usual, I went to the study myself to see what the authors actually reported, and it’s a good thing I did, since the actual data showed the exact OPPOSITE.  In comparison with a baseline “normal” diet, the high-palmitoleic diet very slightly increased HDL, decreased LDL, and decreased total cholesterol.  Beneficial results all around.  So how did the reviewer get it so wrong?  Well, the study did report  that palmitoleic acid decreased HDL and increased LDL, but only relative to oleic acid.  So in other words, palmitoleic acid didn’t increase HDL or increase LDL quite as much as oleic acid did.   And guess what—in the same study, it was found that palmitic acid (a saturated fat) increased good HDL cholesterol more than palmitoleic acid did (even though palmitoleic acid is a monounsaturated fat).  Palmitic acid also lowered LDL cholesterol as much as palmitoleic acid did, although not as much as oleic acid.  And it’s worth noting that even though the differences were apparently statistically significant, they were very very small.

All of this is just so complicated and interconnected.  Like blindly feeling something rough and thinking it is an elephant, when it is really a rhino.  Or an oak tree. 

So I throw my hands in the air.   I’ve run out of energy trying to figure it out.  Shoulders sagging, I’m about done with this fatty acid mess.  And here is where I stand after a four-week review of the literature:

1.             Most dietary recommendations regarding consumption of saturated, monounsaturated, and polyunsaturated fatty acids are misleading, overly simplistic, and probably wrong.

2.            There is conflicting data regarding saturated fats, but they are probably at least neutral and may even be good for you.  I guess it’s possible that they could be bad, but the support for that proposition is sketchy at best.

3.            Polyunsaturated fatty acids are a mixed bag, some good (omega-3 fatty acids) and some bad (omega-6 fatty acids).

4.            Synthetic trans fats are bad, and natural trans fats are good.

And where have a few decades of recommendations to “reduce our saturated fat intake”  gotten us?  McDonald’s french fries are a good example.   They used to be cooked in beef tallow, but in 1990 McDonald’s switched to partially hydrogenated vegetable oil to reduce saturated fat and thus make them “healthier”.  Then in 2002 it was announced that they would be again be changing their french fry oil, this time to a different vegetable oil that was lower in trans fats.  And finally in 2009 it was announced that McDonald’s oil would in the future be 100% trans fat free.  So what has really happened is that saturated fats (neutral or good) and monounsaturated fats (good) have gradually been replaced by trans fats (bad) and/or unspecified polyunsaturates (either bad or good).

Take a look at the fat profiles of the different cooking oils McDonald’s has used in the past 30 years.  With any luck, they may eventually go back to beef tallow.

MCDONALD’S FRENCH FRY OIL (UNITED STATES)*

	Saturated	Monounsaturated	Polyunsaturated	Trans fat
Beef tallow (before 1990)	43%	50%	4%	3% or less (naturally-occurring)
Vegetable oil (announced 1990)	23%	32%	12%	33% (synthetic)
Vegetable oil (announced 2002)	19%	32%	32%	18% (synthetic)
Canola/corn/soy blend (announced 2009)	14%	?**	?**	0% (or less than 1%)

  *All percentages rounded to closest whole number, which may result in a total other than 100%.

**I couldn’t find any numbers for monounsaturates or polyunsaturates in the oil McDonald’s is currently using.

For purposes of comparison, here are fat profiles for some of the most common oils used for cooking in the United States.

OILS COMMMONLY USED IN COOKING*

	Saturated Fat	Monounsaturated Fat	Polyunsaturated Fat
Canola oil	7%	63%	28%
Olive oil	14%	73%	11%
Corn oil	15%	30%	55%
Soybean oil	16%	23%	58%
Lard	39%	45%	11%
Coconut oil	91%	6%	3%

*All percentages rounded to closest whole number, which may result in a total other than 100%.

So what am I going to do with my own diet?  Use lard for frying, use olive oil for everything else, and increase my omega-3’s by taking fish oil capsules.  Avoid synthetic trans fats, (which will not be difficult because they have been eliminated from most foods already).  Take my Lipitor.  Reduce carbs and sugar except when I’m exercising, which is most of the time!

THE DIETARY FAT CONUNDRUM - PART 3

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.

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.

THE DIETARY FAT CONUNDRUM - PART 2

n Part 1 of this series on dietary fat, I arrived at two conclusions that appear to be inconsistent with each other:  (1) there is a considerable amount of data indicating that dietary saturated fat may not really be a “bad actor”, and (2) there is also a substantial amount of data indicating that decreasing saturated fats may be beneficial. 

However, the story is complicated by the fact that a decrease in the consumption of saturated fat is almost inevitably accompanied by an increase in the consumption of unsaturated fats, and it appears that some polyunsaturated fatty acids may be “bad” and some may be “good”, or at least neutral.  (We’ll leave the issue of monounsaturated fats for another day.)

Dietary recommendations to increase polyunsaturates are probably useless because there are two polyunsaturated fatty acids that are essential to one’s diet, yet appear to have opposite effects.  I’m talking about omega-6 fatty acid and omega-3 fatty acid.  And many foods, especially some vegetable oils (such safflower, sunflower, SOYBEAN, and CORN oils) are very rich in omega-6 fatty acids, which seem to be the primary culprit.  Soybean oil and corn oil—I think you may know where I’m going here.  It seems that almost every food in the so-called “Western diet” contains one of these two oils.

Now, the science around omega-6 fatty acids is really very deep, not the nutritional aspects, but rather the relationship between omega-6 fatty acids and inflammation—at least one Nobel Prize has been awarded in this area.  It turns out that the omega-6 fatty acids are part of the inflammatory process, and many drugs that have been developed to reduce pain target that process, which involves the conversion of omega-6 fatty acids to inflammatory compounds such as prostaglandins.  So when you take aspirin or ibuprofen, for example, what you are really doing is trying to inhibit the formation of inflammatory compounds.

Pain reduction, of course, is a huge area of research.  And since much pain is caused by inflammation, there is a lot of money pouring into the effort to reduce inflammation.  Moreover, inflammation seems to be the foundation not only of pain, but also heart disease and many other problems, from multiple sclerosis to dry eyes.  As a result, a lot is known about omega-6 fatty acids and their conversion into inflammatory compounds.

Omega-6 was the first polyunsaturated fatty acid to be discovered, and in the 1960’s it was thought that omega-6 was the ONLY one.   So, when studies first came out showing a correlation between saturated fatty acids and cardiovascular disease (now increasingly questionable, see Part 1 of this series), nutritionists recommended that we all decrease our saturated fats and increase our polyunsaturated fats—and who knew, at the time,  WHICH fatty acid we were increasing?  I’m sure the dieticians said something like, “Oh, just use corn oil or olive oil, or palm oil, or peanut oil—you know, they’re all the same.”

Not.

No wonder the results of the many dietary fat studies have been so goofy and variable.

So what does the scientific data say about omega-6 fatty acid as it relates to nutrition?

First, omega-6 fatty acid has the “common name” linoleic acid.  That’s linoLEic acid. (Omega-3 fatty acid has the common name linolenic acid.  Read: linoLENic acid.  Easy to confuse.)

Linoleic acid is commonly found in vegetable oils.  You can look these up on the web yourself, but what is important here is that corn, soybean, and safflower oil are very rich in linoleic fatty acid.

In 2013 scientists reanalyzed the data generated in a 7-year Australian study (1966 to 1973) involving 458 men, aged 30-59 years, each of whom had had a recent coronary event.  The “reduced polyunsaturated fatty acid” group was given liquid safflower oil (high in omega-6 fatty acid) as a dietary substitute for animal fats and vegetable shortenings in cooking oils, salad dressings, and baked products, and safflower oil margarine to be used in place of butter and common margarines.  Guess what they found—substituting omega-6 fatty acids for saturated fat RESULTED IN A STATISTICALLY SIGNIFICANT 6% INCREASE IN DEATHS, AND A 6% INCREASE IN CARDIOVASCULAR DISEASES.  How about that—you think you are going to show that decreasing saturated fats is a “good” thing, and you end up killing some of your patients.

And interestingly, this negative result occurred in spite of the fact that substituting safflower oil for other dietary fats caused a decrease in the subjects’ total cholesterol, primarily by reducing levels of low-density lipoprotein (the “bad” cholesterol)—which you would also expect to be a good thing.  The scientists who did the reanalysis have proposed a model to explain why this may be so, but a detailed examination of their theory will have to be the subject of another blog post (perhaps).  Suffice it to say that the omega-6 gets oxidized to a form that binds with low-density cholesterol, which then ends up as arterial plaque.  Get it?  The omega-6 lowers low-density cholesterol because it is changing it into a form that is actually harmful.  Oh dear.

Well, this study is causing a bit of a stir, as you might imagine.  The British Medical Journal, the one that published the original report in the 1970s (without the newly-analyzed data), has a bit of egg on its face.  One has to wonder why this startling information was not reported until 2013, when the trial ended way back in 1973?  Apparently the answer is that the authors ran out of money to do a more thorough analysis.  Well, you can’t do research without money, so maybe so.  CBC News reported in February 2013 that perhaps one-half of clinical trials are NEVER published.  (This too will perhaps be the subject of another blog post.)

On February 5, 2013, the British Medical Journal published a “comment” on this paper, and I include a portion of it here:

“The American Heart Association recently repeated advice to maintain, and even to increase, intake of omega 6 PUFAs (polyunsaturated fatty acids). This advice has caused some controversy, because evidence that linoleic acid lowers the risk of CVD (cardiovascular disease) is limited—most trials that claimed to investigate the effect of exchanging saturated fat for linoleic acid involved multiple dietary changes or multiple interventions (or both). In particular, studies lowered trans fatty acid intake or increased omega 3 PUFA intake (or both) at the same time as increasing linoleic acid intake. The impact on CVD risk or mortality of replacing saturated fat with linoleic acid without changes in other fatty acids has rarely been investigated, and no large randomized controlled trial has recently explored this important question…. The new analysis of these old data provides important information about the impact of high intakes of omega 6 PUFAs, in particular linoleic acid, on cardiovascular mortality at a time when there is considerable debate on this question. The findings underscore the need to properly align dietary advice and recommendations with the scientific evidence base. It is important when assessing this evidence base that subtle, and in some cases unsubtle, aspects of study design are properly considered. For example, outcome of studies in which intakes of saturated and trans fatty acids are lowered while intakes of omega 6 fatty acids and omega 3 PUFAs are increased may be most strongly influenced by changes in trans and omega 3 fatty acids. They should not be interpreted as showing an effect of omega 6 PUFAs.”

I have to say that this is very cool.  I don’t mean it’s cool that there may be misleading advice out there that is killing people, but that the interplay between advancing science and public policy is cool.  It also reiterates what I said at the beginning of this blog series—the data is too sketchy to be making policy recommendations.

I wonder what the American Medical Association thinks about this?  Oh, wait, here we go—on February 7, 2013, the AMA had this to say:

“The British Medical Journal study is interesting, but not conclusive. It is offset by a large body of scientific evidence that continues to show cardiovascular benefits associated with eating mono- and poly-unsaturated fat, rich in Omega-6 linoleic acids, in place of saturated fat. . . .”

I don’t know about you, but I find this to be quite surprising—no change in the AMA’s position on omega-6’s?  Not even a statement that they will give this new data “due consideration”?  One has to wonder about this, especially since everybody else seems to be pretty excited by the new data.  Well, my understanding is that the U.S. edible oils manufacturing industry is $55 Billion—and that figure doesn’t even include farm production of corn and soybeans (grains that are high in omega-6’s).  What influence do you think these industries could have on the federal government’s interest in doing research in this area—research possibly showing that consuming omega-6’s in the form of corn oil and soybean oil might have negative effects on our health?

What fun!

We must keep in mind, however, that this reanalysis doesn’t stand alone—it follows numerous studies indicating that the story isn’t as simple as omega-6 fatty acids just being “bad.”  They are, in fact, essential to our health—they seem to be “bad” only when they are consumed in excess relative to omega-3 fatty acids.  In other words, what seems to be emerging is that it is the ratio of omega-6 fatty acids to omega-3 fatty acids that is important.

But first a little history about omega-3 fatty acid, or linoLENic acid. 

Unlike omega-6 fatty acid, the importance of omega-3 fatty acid really started to emerge in 1975 with the discovery that the Greenland Inuit Eskimos had a level of cardiovascular disease that ranged from very low to virtually nonexistent—and that they had two times as much omega-3 fatty acid in their blood as the Eskimos living in Denmark.  The Greenland Eskimos also consumed very low amounts of omega-6 compared to their cousins living in Denmark.  Oh, and the Greenland Eskimos had higher levels of saturated fat and lower levels of both triglycerides and cholesterol in their blood plasma than the Danish Eskimos did.  Interestingly, an analysis comparing the diets of Greenland Eskimos and with the diets of Danes (not Danish Eskimos in particular) showed that the Greenland group consumed less carbohydrates, more protein, about the same amount of fat, more cholesterol, LESS saturated fatty acids, and less omega-6 fatty acids. 

Well, the omega-3 story has evolved since then, and today we know that the “Western diet” is very high in omega-6 and low in omega-3 fatty acids, like that of the Danish group.

And now, of course, I have to report on meta-analyses of omega-3 fatty acids.  What is the data showing?

Meta-Analysis #1*.  Published in 2012.  20 randomized studies involving 68,680 patients.  Examined the effect of omega-3 supplements on cardiovascular disease.  The average age of the test subjects was 68; they received supplemental omega-3 for two years.  The amount of the supplement was 1 gram or less per day per person.  What did they find?  The authors concluded there was NO statistically significant correlation between supplementation and cardiovascular disease or death.  And that’s it.  However, when you look at the actual data, what is interesting is that nearly all the studies showed that the supplemented groups had less cardiovascular disease, but that it wasn’t statistically significant.  Well, that’s interesting . . .

Meta-Analysis #2**. Published in 2013. 21 randomized studies involving 46,737 patients. Compared omega-3 fatty acid supplementation (either via capsules or diet alterations) to a normal diet.  Most of the studies included patients at high cardiovascular risk.  The authors were not specific about the amount of omega-3’s consumed.  They found a statistically significant 10% DECREASE in cardiovascular events of any kind and a 9% decrease in cardiovascular death.

So, given these two meta-analyses, I’d say it is looking like the omega-3 fatty acids may have a positive effect on cardiovascular disease. 

Today there seems to be an emerging consensus to the effect that increasing our consumption of omega-3 fatty acids and decreasing our consumption of omega-6 fatty acids is beneficial.  There are many reports that the typical “Western” diet includes an overabundance of omega-6 fatty acids, probably due in part to the consumption of the corn and soybean oils that are found in so many of our foods.  Omega-6 fatty acids are also prevalent in feedlot-produced beef—probably due to the use of corn and soybeans as feed.  Think poultry and eggs, too. 

In fact, Western diets have ratios of omega-6 to omega-3 fatty acids in the neighborhood of 15:1, although many scientists believe the optimal ratio is closer to 4:1—and some even advocate reversing the ratio to 1:4 (only one-fourth as much omega-6 as omega-3).  I don’t know how good the science is here, but apparently the problem with too much omega-6 is that it shifts the omega-3 fatty acids towards the same pathway as omega-6’s, which results in inflammation. 

All I know is that I’d sure like an updated analysis of diets, blood plasma, and cardiovascular disease in other “traditional” populations like the Greenland Eskimos.

But, overall, I bet that my prediction at the start of this blog series is correct—the studies that have been done so far have too many unknowns relative to the exact types and quantities of fatty acids consumed by the test subjects.  We just haven’t had sufficiently detailed knowledge (either quantitative or qualitative) about what food is going into patients’ mouths during the last 30 or 40 years to be giving accurate advice. 

So there.

And how this relates to the whole controversy concerning the Mediterranean Diet vs. the recommended U.S. Food Pyramid vs. the South Beach Diet vs. the Paleo Diet, I don’t know.  I see there is a new report out on the results of a study comparing the Mediterranean diet with a low-fat diet.  7,447 people enrolled, ages 55-80.  Well, the authors conclude we should consume more olive oil—because the (statistically significant) rate of cardiovascular events among the Mediterranean diet group was 0.6% lower than it was among the low-fat diet group.

Only 0.6%?  That seems too small to worry about if you like red meat, statistically significant or not.

But the fat story also includes recent recommendations regarding “trans fats.”  You certainly know by now that labeling of trans fats in food is mandatory in the United States.  And as of January 1, 2010, California became the first state to ban trans fats in restaurants.  Scientifically sound?

Next blog post.
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*Evangelos C. Rizos, MD, PhD; Evangelia E. Ntzani, MD, PhD; Eftychia Bika, MD; Michael S. Kostapanos, MD; Moses S. Elisaf, MD, PhD, FASA, FRSH (September 2012). "Association Between Omega-3 Fatty Acid Supplementation and Risk of Major Cardiovascular Disease Events A Systematic Review and Meta-analysis". JAMA 308 (10): 1024–1033
**Javier Delgado-Lista, Pablo Perez-Martinez, Jose Lopez-Miranda, Francisco Perez-Jimenez. 2012. “Long Chain Omega-3 Fatty Acids and Cardiovascular Disease: a Systematic Review. British Journal of Nutrition 107: S201-S213