The Truth About Saturated Fats

SATURATED FATS The Truth!

By: Tony Escobar – October 2006

Most health professionals and most people actually believe that saturated fat will increase your risk of heart disease and heart attacks! This is NOT TRUE! A recent study validates this.

The Strong Heart Study, published in the American Journal of Clinical Nutrition was very profound. The study incorporated 2938 Native American Indians in the southwestern United States for approximately 10 years.

The study was surprising as both total fat intake and saturated fat intake were observed as with any increase in the risk of heart disease.

Health professionals for many years have told us to avoid saturated fat, because it is bad for you and will expose you to heart disease and cancer?

Human beings have eaten animal products since they arrived on the earth and have consumed saturated fats for most of that time.

Most heath experts agree that saturated fat WILL elevate LDL cholesterol assuming that this increases the risk of coronary artery disease. It is sad to note that this misconception has blinded health professionals to the benefits of saturated fats in human diets.

If saturated fat was potentially dangerous and had NO health benefits or had why would perhaps the healthiest food known to man, breast milk contain a large amount of saturated fat … butyric, caproic, caprylic, capric, lauric, myristic, palmitic and stearic acids which provide miraculous health benefits to ensure the growth, immunity and rapid development of new babies.

Saturated fats are found in all body tissues. Saturated fats are essential to human health.

Saturated fats ensure many health benefits:

• They represent a major component of the phospholipids of all cell membranes

• They provide the most important fuel for your heart

• Caprylic acid represents a powerful anti-viral component of saturated fat

• Saturated fats represent anticaries, antiplaque and anti fungal agents (lauric acid)

• Saturated fats may actually lower LDL cholesterol levels (palmitic and stearic acids)

There is an association between fat and heart disease and there absolutely is. The culprit is NOT saturated fat but TRANS FAT. The many studies that implicate saturated fat do not make any distinction between saturated and trans fats. Therein lays the problem! Let’s discuss a particular study.

This study measured the effects of trans fat, associated with fried foods and processed foods such as cookies, cakes, chips, fries, crackers and pastries, and of saturated fat, found in meat, butter and some dairy products, on blood vessel function and cholesterol levels.

According to the results, the trans-fat diet reduced blood vessel function by 30% and lowered HDL ("good")-cholesterol levels by about one fifth, compared with the saturated-fat diet. Previous research has shown that trans fats, like saturated fats, also raise LDL ("bad")-cholesterol levels.

This suggests that trans fatty acids increase the risk of heart disease more than the intake of saturated fats.

The major sources of trans fats in our diet are the ready-made baked goods and fried fast foods. These foods are not labeled, so do you determine how much trans fat is in them?

Trans fat accounts for 4% to 7% of dietary fat intake in the US.

It is amazing to me just how many health professionals believe that saturated fat is dangerous to human heath when the truth of the matter is this is a myth. Of course it is not healthy when eaten in the large quantities that most people consume.
However, trans fat in bakery goods is FAR worse than saturated fats.

Have you heard about the new healthy, low trans fat margarines on the market to day?

These are simply expensive alternatives to butter.

Many health professionals and researchers are now saying that margarines which are advertised as "trans fatty acid free" appear to be a healthier choice than butter. Some say, “Compared with butter, margarine had healthier effects on the types of cholesterol linked to increasing the risk of heart disease.” This is absurd especially when you know the facts! Butter and margarine contain varying proportions of different types of fatty acids. There are a number of types -- including saturated, monounsaturated, polyunsaturated and trans unsaturated fatty acids -- and each type has unique effects on different kinds of cholesterol.

Study is available on the American Journal of Clinical Nutrition Website: 1998; 68: 768-777.

The study documented, for example total cholesterol levels were 3.5% lower on the straight margarine diet, and 5.4% lower on the “trans fatty acid free” margarine diet, than on the butter diet. And LDL cholesterol levels were 4.9 % lower on the margarine diet and 6.7 % lower after the trans fatty acid free diet, than on the butter diet.

This is a typical study that demonstrates just how one can incorporate a misunderstanding of health to make a recommendation that obviously appears healthy but will actually destroy your health.

Traditional, allopathic medicine does not understand that health is much more than a lower cholesterol level. Margarine, whether it is straight or non-trans fat is still processed, liquid plastic.

These chemicals and toxins were never designed to be in your body, period! Aside from margarine there are many hidden sources of trans fats such as many salad dressing, most all crispy snacks, crackers and potato chips, most mayonnaise and most every fried food.

A team of researches from Europe have discovered that diet plays a significant role in the increased incidence of allergies, affecting 67,000,000 Americans today.

Allergy 2001; 56:425-428

Their study found that children who eventually developed allergies ate less butter and more margarine compared with children who did not develop allergies.

This study is not the first to allege that certain types of fatty acids may play a role in the onset of allergic illnesses. Polyunsaturated fats like those in margarine promote the formation of prostaglandin E2, a substance that promotes inflammation and causes the immune system to release a protein that triggers allergic responses.

The study’s results validate the hypothesis that the quality of the fat consumed in the diet is important for the development of allergies in children.

Preventing allergies is possible by supplementation or by changing the fatty acid composition of the diet of young children.

Why so much Asthma today? There are many reasons and explanations for the observed epidemic in asthma today.

Hygiene obviously is one and the use of drugs like Tylenol to control fevers are clearly important contributing factors as documented by recent studies.

Diet is perhaps the key culprit. Sugar, for example is perhaps a major cause. Removing sugars and foods that turn to sugar (juices and carbohydrates) along with eliminating processed, pasteurized cows milk is also another way to effectively reduce asthma.

Trans Fats are also a key factor.

Trans fats like the trans fats found in margarines and most all pastry goods is also important to minimize the risk of asthma or in the control of the disease.

TRANS FAT, THE MISSING LINK!

If researchers were to be more open in evaluating the risks of heart disease by measuring the levels of trans and saturated fat I believe they would find a completely different story. They would certainly find trans fat is the culprit.

Trans fat will increase blood levels of low density lipoprotein (LDL), or "bad" cholesterol, and will lower the levels of high density lipoprotein (HDL), known as "good" cholesterol. Trans fat will cause major clogging of arteries and contribute greatly to the onset of type 2 diabetes and other serious health problems. It will also increase the risk of heart disease. But many food companies use Trans fat instead of oil because it’s cheaper, it extends the shelf life of products and it makes food taste better.

Your body absolutely needs some saturated fat to stay healthy. We don’t need trans fats, period!

Food manufacturers are now forced to document how much trans fat is in their foods. They don’t care! They manipulated the laws so that they could say it was trans fat-free if had less than 500 milligrams of trans fat per serving.

Trans fats, also known as trans fatty acids, are artery-clogging cancer causing fats that are formed when vegetable oils are made into margarine or shortening.

Girl Scout cookies! Boy it is nice to help this wonderful organization isn’t it? I used Can you believe that their cookies can be harmful to you. Their cookies are the most inexpensive to make and are loaded with trans fats and that’s a fact! It is sad that their cookies contain the one of the most harmful foods that you can eat.

Avoid trans fats at all costs, and don’t worry much about saturated fat as long as it originates from healthy food sources that are not contaminated with trans fats.

Healthy lungs require saturated fats to function efficiently avoiding the very important phospholipid class a called lung surfactant, which is a special phospholipid with 100 percent saturated fatty acids. One is called dipalmitoyl phosphatidylcholine and there are two saturated palmitic acid molecules attached to it.

When one consumes a partially hydrogenated fats and oils in excess, the trans fatty acids are put into the phospholipids where the body normally wants to have saturated fatty acids and the lungs may not work effectively.  Several studies has suggested that trans fatty acids contribute to asthma in children.

Studies have shown that having enough saturated fat in the diet will prevent a stroke and will help protect the kidneys from disease. Research validates the need for certain kinds of saturated fatty acids, which are found only in natural fats such as animal fats (Butter), as well as coconut and palm kernel oil.

Saturated fats are not the major cause of heart disease and cancer. In fact, they are essential to good health and body chemistry:

Saturated fats are important to the health of our bones. For calcium to be effectively absorbed into the bones, at least 30% of the dietary fats should be saturated.

Saturated fats protect the liver from alcohol and other toxins, as well as many drugs

Saturated fats are important to the immune system and enhance the absorption of water soluble minerals.

Saturated fats are needed for the proper utilization of essential fatty acids.

Omega-3-6-9 fatty acids are better retained in the tissues when the diet is rich in saturated fats.

Saturated fats are necessary for optimum brain function as they help in the production of important brain chemicals, such as serotonin, dopamine, norepinephrine, melatonin, insulin, and prostaglandins

Reduced serotonin levels from stressful lifestyles, lack of sleep & exercise, poor eating habits, and lack of saturated fatty acids are connected with ADD, irritability, depression, aggression, anxiety, lack of concentration, chronic pain, restlessness or fatigue, nausea, obsessive-compulsive disorder, weight gain or loss, fibromyalgia, arthritis, chronic fatigue syndrome, heat intolerance and other syndromes.   Fluctuating serotonin levels are connected with bipolar disorder (manic depression) and hypomania. 

Reduced dopamine/norepinephrine caused by lack of purpose, exercise m and proper saturated fats may manifest as ADD, impulsivity, lack of concentration, restlessness, and depression or loss of pleasure.  Dopamine is the "feel good" chemical which illegal drugs mimic (such as cocaine, heroin, marijuana) as well as cigarettes, coffee and alcohol. Ritalin and other ADD drugs are thought to increase dopamine activity.

Modern food processing has completely altered the types of fatty acids we consume.  Since our brain is composed largely of fatty acids, we are missing the "bricks" needed for normal brain development and repair.  In addition, we are eating lots of man-made chemicals and trans fats.  Food colorings affect brain chemical production and are mostly made from petroleum products.

POST MENAPAUSAL WOMEN STUDY

American Journal of Clinical Nutrition November 2004 80(5); 1102-1103

For many years now, professionals associated with the medical community have believed diets high in saturated cause heart disease; this is due to saturated fats boosting blood concentrations of harmful, low-density-lipoprotein (LDL) cholesterol, which leads to the accumulation of plaque in the arteries. Moreover, this buildup may eventually lead to heart attacks and strokes.

However, profound studies show that diets high in these fats might have the complete opposite effect in postmenopausal women.

During a three year study, researchers examined the diets and coronary artery conditions of 235 women in the United States with an average age of 66. Most of the women consumed relatively low amounts of fat compared to the typical American diet: About 25 percent of the group's calories came from fats, compared to 40 percent or more in American diets. Other characteristics the subjects had in common included:

• All were postmenopausal

• Seventy five percent were overweight and forty percent were considered obese

• One-quarter had diabetes

• Two-thirds were taking hormone supplements

At the start of the study, researchers took X-ray images of 10 places along each woman's heart arteries. (All the subjects were found to have some plaque buildup.) The women kept comprehensive records of what foods they ate and how much, including what kinds of oils they used for frying and baking. At the end of the three-year period, researchers

They discovered that women who had regularly eaten the highest amounts of saturated fats had the least amount of additional plaque buildup in their arteries. Also, women who ate more saturated fat had a healthier balance of good and bad cholesterols and more desirable blood concentrations of various kinds of fats.

Researchers adjusted the results based on factors such as age, education, smoking habits and use of medication.

Here is an incredible word for word interview!

Health Risks from Processed Foods and the Dangers of Trans Fats

Dr. Mary Enig Interviewed By Richard A. Passwater, Ph.D.

Mary G. Enig, Ph.D., a nutritionist widely known for her research on the nutritional aspects of fats and oils, is a consultant, clinician, and the Director of the Nutritional Sciences Division of Enig Associates, Inc., Silver Spring, Maryland.

She received her PhD in Nutritional Sciences from the University of Maryland, College Park in 1984, taught a graduate course in nutrient-drug interactions for the University's Graduate Program in Nutritional Sciences, and held a Faculty Research Associateship from 1984 through 1991 with the Lipids Research Group in the Department of Chemistry and Biochemistry.

Dr. Enig is a Fellow of the American College of Nutrition, and a member of the American Institute of Nutrition. Her many years of experience as a "bench chemist" in the analysis of food fats and oils, provides a foundation for her active roles in food labeling and composition issues at the federal and state levels.

Dr. Enig is a Consulting Editor to the "Journal of the American College of Nutrition" and formerly served as a Contributing Editor to "Clinical Nutrition." She has published 14 scientific papers on the subject of food fats and oils, several chapters on nutrition for books, and presented over 35 scientific papers on food and nutrition topics.

She is the President of the Maryland Nutritionists Association, past President of the Coalition of Nutritionists of Maryland and was appointed by the Governor in 1986 to the Maryland State Advisory Council on Nutrition and served as the Chairman of the Health Subcommittee until the Council was disbanded in 1988.

I first learned of Dr. Mary Enig's research from a 1978 report in the Federation Proceedings. We met shortly after that, and since I had written about trans fats several times in Supernutrition, we had common concerns about the effect that these trans fats from processed foods were having. We were both concerned particularly about the misconception that processed margarine was better than natural butter.

In several visits by Dr. Mary Enig to the Solgar Nutritional Research Center I quickly learned that she was an exacting scientist who is not afraid to speak out and who supports good nutrition, not just going along with the establishment's party line.

While studying for her Ph.D. at the University of Maryland, often she would first respond with the "correct" answer that was expected, and then she would explain why new research indicated "alternatives," such as optimal vitamin and mineral nourishment, provided a better answer. It is not easy be credentialed by the "system," while your own research shows other facts.

In her 1978 report, Dr. Enig challenged the speculation concerning the relationship of dietary fat and cancer causation. She concluded that correlations between the increase in per capita dietary fat intake and total cancer mortality over a sixty-year period show significant positive correlations for total fat and vegetable fat, and negative correlation for animal fat.

That the cancer rate is higher when the amount of vegetable fat or total fat is higher in the diet, but the cancer rate is lower when there there is more animal fat in the diet. These findings were unpopular then as they are today, but they are still correct. It is convenient to blame everything on red meat and animal fat, and believe that vegetable oil is the great dietary salvation-even if it is partially hydrogenated. At least that is what the vegetable oil people would like everyone to believe.

Now, we are not saying that lots of dietary fat is good for you and that vegetables are not good. Eating vegetables, fruits and other whole foods is very desirable. However, that is not the same as eating partially-hydrogenated vegetable oils.

Americans eat too much fat (especially partially hydrogenated vegetable oils) and not enough fruits and vegetables.

The problem is that the typical American is not eating enough whole foods, but instead, is eating too much partially-hydrogenated vegetable oil-a fractionated food-that has been made into "funny foods" such as margarine or added to baked goods. Such "funny foods" are far differentthan real whole foods.

Hydrogenation ruins the nutritional value of vegetable oils! Why would anyone want to ruin the nutrition value of vegetable oils? The purpose of hydrogenation is to solidify an oil so that it can be made to resemble real foods such as butter.

The hydrogenation process imparts desirable features such as spreadability, texture, "mouth feel," and increased shelf life to naturally liquid vegetable oils.

In the hydrogenation process, vegetable oil is reacted under pressure with hydrogen gas at 250 - 400oF for several hours in the presence of a catalyst such as nickel or platinum. However, this industrial process cannot control where the hydrogen atoms are added to the "unsaturated" double bonds.

Randomly adding hydrogen atoms to polyunsaturated fats converts natural food components into many compounds, some of which have never seen before by man until partially hydrogenated fats were manufactured.

Some of the several dozens of altered compounds created in the manufacture of partially-hydrogenated fats are "trans" fatty acids. Fatty acids are the building blocks of fats, much like amino acids are the building blocks of proteins.

Other new compounds accidentally synthesized include fatty acids having double bonds translocated to new and un-natural positions, and various molecular fragments. Many of these altered compounds are detrimental to health.

Since "trans" fats are so detrimental to our health. permit me to briefly review the relevance of distinguishing between "trans" and "cis" fats before chatting with Dr. Enig. Recently, in the September issue, in the interview with Dr. Jim Clark and Mr. Lance Schilipalius, we discussed "trans" isomers of carotenoids. "Trans" means the same thing here. "Cis" and "trans" isomers refer to how identical atoms are added to double bonds.

When the atoms are added to the same side of the double bond, the compound is called "cis" and the molecule is bent because of the crowding of the atoms on one side.

When the atoms are added on opposite sides of the double bond, the compound is called "trans" and molecule is "space-balanced" and straightened. The shape of a molecule is important because enzymes and their substrates-the molecules enzymes act upon-must fit together like a key in a lock.

Dr. Enig will discuss this during the interview, but the important thing to remember is that natural polyunsaturated fatty acids are "cis" compounds and are bent. Partial hydrogenation produces many un-natural "trans" fats which are straight and not intended for use in the human body.

You don't have to understand the difference between "trans" and "cis," but it is important that you know that there is a difference because, as Dr. Enig will explain, it can affect your health.

Passwater: Dr. Enig, a lot of people are interested in "trans" fats now. You have been researching them since 1977. How are trans fats harmful to us?

Enig: More than a decade of research at the University of Maryland, as well as research that was being done at other institutions, showed that consumption of trans fatty acids from partially hydrogenated (a process that adds hydrogen to solidify or harden) vegetable fats and oils had many adverse effects in health areas such as heart disease, cancer, diabetes, immunity, reproduction and lactation, and obesity.

It is rather easy today to come up with a long list of these adverse effects from the published research done by many scientists around the world, as well as the researchers at the University of Maryland.

The reason there is so much recent interest is that during the past three years there has been a number of major research reports published in prestigious medical journals that caught the attention of the press.

These and earlier reports had shown, for example, that consumption of trans fatty acids lower the "good" HDL cholesterol in a dose response manner (the higher the trans fat level in the diet, the lower the HDL level in the blood) and raise the atherogenic lipoprotein(a) in humans as well as raising the "bad" LDL cholesterol and total blood cholesterol levels by 20-30 milligram-percent.

These studies have usually been shown in independent non-industry studies. Perhaps the most significant event though was the report from researchers at Harvard University, who evaluated more than 85,000 women in a long-term prospective study and found that there was a significantly higher intake of trans fatty acids in those individuals who developed heart disease.

As regards to the question of cancer, trans fatty acids induce adverse alterations in the activities of the important enzyme system that metabolizes chemical carcinogens and drugs (medications), i. e., the mixed-function oxidase cytochromes P-448/450.

The initial research in this area was done by the Maryland group in collaboration with the U. S. Food and Drug Administration, and was followed by the more extensive evaluation that I did for my Ph.D. dissertation; several groups around the country and the world also reported the same or similar results. Several groups around the world reported a higher intake of partially hydrogenated fats in those individuals who have developed cancer.

Both primate and human studies have shown inappropriate handling of blood sugar; trans fatty acids decrease the response of the red blood cell to insulin, thus having a potentially undesirable effect in diabetics. The primate research was initiated at Maryland in collaboration with the U. S. Department of Agriculture and the National Institutes of Health, and the human research is from the University of Pittsburgh and quite recent.

One major concern is that trans fatty acids adversely affect immune response by lowering efficiency of B cell response and increasing proliferation of T cells. This was shown in research done at Maryland using a mouse model and although there are reports from clinicians that there are problems of immune dysfunction in humans it still needs to be evaluated systematically in humans.

Recent research from outside the U. S. has indicated that trans fatty acids interfere with reproductive attributes and of concern is the finding that trans fatty acids lower the amount of cream (volume) in milk from lactating females in all species studies including humans, thus lowering the overall quality available to the infant. The latter research was done at Maryland by my colleague Dr. Beverly Teter.

Basically, trans fatty acids cause alterations to numerous physiological functions of biological membranes that are known to be critical for cell homeostasis, e.g., appropriate membrane transport and membrane fluidity, and these fatty acid isomers produce alterations in adipose cell size, cell number, lipid class and fatty acid composition.

Passwater: Now that trans fats are becoming of more interest, the term may still just be a buzz word to many of our readers. Would you explain just what are trans fats? Where do they come from? How are they formed?

Enig: To understand what trans fatty acids are you have to understand what fatty acids are. Fatty acids are basically chains of carbon with a carboxyl group (COOH) at one end that can react (e.g., combine) with another molecule.

When fatty acids are in fats or oils they are combined with glycerol in the proportions of three fatty acid molecules to one glycerol molecule and they form triacylglycerols or in common terminology, triglycerides.

Fatty acids come in different chain lengths ranging from three carbons long (propionic acid) to 24 carbons long (lignoceric acid). These fatty acids are either "saturated" (with an adequate number of hydrogen atoms) and chemically stable, or they are "unsaturated" (missing adequate hydrogens) and chemically unstable.

If a fatty acid is missing two hydrogens, it is called a monounsaturated fatty acid, and in place of the two hydrogens, the adjacent carbons "double" bond to each other.

If the fatty acid is missing four or six or more hydrogens, it is called a polyunsaturated fatty acid, and it is even more unstable than the monounsaturated fatty acid. Because the double bonds in naturally occurring plant oil fatty acids are curved with a "cis" configuration, the fatty acids cannot pack into a crystal form at normal temperatures so their presence produces a liquid oil. Saturated fatty acids have a straight configuration and can pack into a solid crystal at normal temperatures.

If the unsaturated fatty acids are altered by partial hydrogenation to straighten the chains so that they have some of the physical packing properties of saturated fatty acids they have had their "cis" double bond changed to a "trans" double bond and they turn a technically mostly unsaturated oil into a solid fat.

The trans fatty acids are the same length and weight as the original "cis" fatty acid they were formed from, and although they have the same number of carbons, hydrogens, and oxygens they are shaped differently in space.

The term that is used is that they are "isomers." The problem arises when a large number of the trans fatty acids are consumed from foods and they are deposited in those parts of the cell membranes that are supposed to have either saturated fatty acids or "cis" unsaturated fatty acids; under these circumstances the trans fatty acids essentially foul up the "machinery."

Although the trans fatty acids are chemically "monounsaturated" or "polyunsaturated" they are considered so different from the "cis" monounsaturated or polyunsaturated fatty acids that they cannot be legally designated, e.g., monounsaturated for purposes of labeling. Most of the trans fatty acids produced by the partial hydrogenation process are chemically monounsaturates.

There have always been small amounts of one kind of trans fatty acids in the human diet from the ruminant fats (dairy, sheep, goat, deer, buffalo, antelope, etc.) because the microorganisms in the rumen try to get rid of the polyunsaturated fatty acids that are found in the plant foods eaten by these animals.

In the early days of trans fatty acid research, the researchers assumed that the trans fatty acids found in ruminant fats were no different than those produced by partial hydrogenation in the factory.

But the studies showed that not only was the amount much smaller (e.g., the fat in butter might be 2-3% of the ruminant trans), the effect on the "machinery" in the cell membranes was not different than without the trans. Yet all studies feeding the trans produced by partially hydrogenating the vegetable oils showed the adverse effect on the cell "machinery."

Passwater: Why are trans fats a problem?

Enig: The various mechanisms through which the trans fatty acids disrupt function are related in part to the ability of trans fatty acids to inhibit the function of membrane related enzymes such as the delta-6 desaturase resulting in decreased conversion of e.g., linoleic acid to gamma-linolenic acid or arachidonic acid; interference with the necessary conversion of omega-3 fatty acids to their elongated tissue omega-3 fatty acids; and escalation of the adverse effects of essential fatty acid deficiency.

This latter effect was shown especially by the work of Dr. Holman and his colleagues at the Hormel Institute at the University of Minnesota, the other effects have been shown by many researchers including the University of Maryland researchers.

Passwater: What were your early findings and what got you interested in this area of research?

Enig: My initial published research in 1978 when I was at the University of Maryland showed that trans fatty acids, which were increasing in the food supply at the time and which had not been catalogued in any of the food data tables, were the very factors that explained the positive statistical relationship between the increase in cancer mortality and vegetable fat consumption in the U. S.

It was clear from the literature that once the trans fatty acids were identified as products of partial hydrogenation and studies were engaged in, there were a number of earlier researchers who questioned the biological safety of the trans fatty acids viz a viz their relationship to both cancer and heart disease.

In fact, Dr. Ancel Keys had originally claimed that the partially hydrogenated vegetable oils with their trans fatty acids were the culprits in heart disease. This was in 1958, and the edible oils industry was very swift in their squelching of that information; they shifted the emphasis to "saturated" fat and started the phoney attack on meat and dairy fats.

Passwater: What have others added to your findings?

Enig: As you have noted in some of your writings, we at the University of Maryland were not the first to raise the issue of trans fatty acids and adverse health effects; Dr. Fred Kummerow from the University of Illinois, Dr. George Mann from Vanderbilt University, and Dr. Edward Pinckney with the American Medical Association had sounded the alarm many years before my plunge into the foray.

In fact, I had drawn heavily on the research findings of Dr. Kummerow and the informative writing of Dr. Mann when I first started to investigate what was known about health effects of trans fatty acids at the time. Our research findings have been duplicated by others, but more importantly other independent researchers have extended and explained many of our findings and concerns.

HERE IS THE STUDY AS DISCUSSED ABOVE

ORIGINAL STUDY

Saturated fat prevents coronary artery disease? An American paradox 1,2

Robert H Knopp and Barbara M Retzlaff

It is an article of faith that saturated fat raises LDL cholesterol and accelerates coronary artery disease, whereas unsaturated fatty acids have the opposite effect (1, 2). One of the earliest and most convincing studies of the better efficacy of unsaturated than of saturated fat in reducing cholesterol and heart disease is the Finnish Mental Hospital Study conducted in the 12 y between 1959 and 1971. In this study, the usual high-saturated-fat institutional diet was compared with an equally high-fat diet in which the saturated fat in dairy products was replaced with soybean oil and soft margarine and polyunsaturated fats were used in cooking. Each diet was provided for 6 y and then the alternate diet was provided for the next 6 y (3). After a comparison of the effects of the 2 diets in both men and women, the incidence of coronary artery disease was lower by 50% and 65% after the consumption of polyunsaturated fat in the 2 hospitals.

In this issue of the Journal, Mozaffarian et al (4) report the opposite association. They found that a higher saturated fat intake is associated with less progression of coronary artery disease according to quantitative angiography. How can this paradox be explained? In food-frequency questionnaires, saturated fat intake is more precisely estimated than is total fat. If saturated fat is more precisely estimated, it will associate more strongly in statistical analyses with the outcome variable, even though other variables—such as total fat or carbohydrate—could be more relevant physiologically. We believe that these possibilities deserve a closer look.

Unlike the diet used in the Finnish Mental Hospital Study, the diet described by Mozaffarian et al was low in fat, averaging 25% of energy. The study subjects were women with coronary artery disease: most were hypertensive, many had diabetes (19–31%), their body mass index (kg/m2) ranged from 29 to 30, and their lipid profile indicated combined hyperlipidemia (triacylglycerol concentration: 200 mg/dL; HDL-cholesterol concentration: 40–50 mg/dL; above-average LDL concentration: 135–141 mg/dL); these characteristics are consistent with the metabolic syndrome. In addition, two-thirds of these women were taking sex hormones. The importance of each of these points is addressed below.

What are the effects of a low-fat, high-carbohydrate diet in comparison with those of a higher-fat, lower-carbohydrate diet? The response differs by the 2 main types of hyperlipidemia: simple hypercholesterolemia and combined hyperlipidemia. In our studies of simple hypercholesterolemia in men, a fat intake <25% of energy and a carbohydrate intake >60% of energy was associated with a sustained increase in triacylglycerol of 40%, a decrease in HDL cholesterol of 3.5%, and no further decrease in LDL in comparison with higher fat intakes (5). In contrast, a low-fat diet in persons with combined hyperlipidemia caused no worsening of triacylglycerol or HDL, but intakes of fat >40% of energy and of carbohydrate <45% of energy for 2 y were associated with a lower triacylglycerol concentration at a stable weight (6). In the subjects of Mozaffarian et al, a greater saturated fat intake paralleled a total fat intake, which ranged from 18% to 32% of energy in the first to fourth quartiles. Modest favorable trends in triacylglycerol and HDL-cholesterol concentrations were observed with higher fat intakes.

Triacylglycerol and HDL-cholesterol concentrations are stronger predictors of coronary artery disease in women, whereas the LDL-cholesterol concentration is a stronger predictor in men (7). Because VLDL triacylglycerol secretion and removal rates in healthy women are double those of men (8), conditions impairing lipoprotein removal would be expected to exaggerate the hyperlipidemic response in women as compared with that in men (9). This sex difference is seen with the development of diabetes. The increment in lipids is greater in women than in men and is associated with a greater increment in coronary artery disease risk in women than in men (9). Similarly, the development of insulin resistance and obesity is associated with a greater lipoprotein increment in women than in men (10). The exaggerated decreases in HDL- and HDL2-cholesterol concentrations observed with the consumption of a low-fat Step II diet in women but not in men appear to be another facet of this effect (11).

The failure of female sex hormones to prevent coronary artery disease has been a great disappointment (9). This effect might also be due to an estrogen-induced increase in lipoprotein entry against a fixed or impaired rate of lipoprotein removal, as might be expected in women with the metabolic syndrome and coronary artery disease.

Would saturated fat still be bad for anyone? Not necessarily. The effect of saturated fat and cholesterol ingestion in the form of 4 eggs/d for 1 mo in obese, insulin-resistant subjects is 33% of that seen in lean, insulin-sensitive subjects, likely because of diminished cholesterol absorption (12). Thus, the classic effects of saturated fat as compared with those of unsaturated fat seen in the Finnish Mental Hospital Study are likely blunted in the subjects of Mozaffarian et al, whereas the effects of low fat and high carbohydrate intakes on triacylglycerol and HDL-cholesterol concentrations appear to be exaggerated by the interactions of female sex, exogenous sex hormones, and the metabolic syndrome. A major effect on cardiovascular disease risk would be the result of hypertriglyceridemia and low HDL-cholesterol concentrations, which are attenuated by an increase in saturated fat intake itself or in total fat intake, for which saturated fat is a more statistically stable surrogate (4).

In conclusion, the hypothesis-generating report of Mozaffarian et al draws attention to the different effects of diet on lipoprotein physiology and cardiovascular disease risk. These effects include the paradox that a high-fat, high–saturated fat diet is associated with diminished coronary artery disease progression in women with the metabolic syndrome, a condition that is epidemic in the United States. This paradox presents a challenge to differentiate the effects of dietary fat on lipoproteins and cardiovascular disease risk in men and women, in the different lipid disorders, and in the metabolic syndrome.

1 From the Northwest Lipid Research Clinic, University of Washington School of Medicine, Seattle

2 Address reprint requests to RH Knopp, Northwest Lipid Research Clinic, University of Washington, School of Medicine, 325 9th Avenue, Seattle, WA 98104. E-mail: rhknopp@u.washington.edu

References:

1. Kinsell LW, Michaels GD, Cochrane GC, Partridge JW, Jahn JP, Balch HE. Effect of vegetable fat on hypercholesterolemia and hyperphospholipidemia: observations on diabetic and nondiabetic subjects given diets high in vegetable fat and protein. Diabetes 1954;3:113-9. [Medline]

2. Grundy SM, Denke MA. Dietary influences on serum lipids and lipoproteins. J Lipid Res 1990;31:1149-72.[Abstract]

3. Miettinen M, Turpeinen O, Karvonen MJ, Elosuo R, Paavilainen E. Effect of cholesterol-lowering diet on mortality from coronary heart-disease and other causes. A twelve-year clinical trial in men and women. Lancet 1972;2:835-8.[Medline]

4. Mozaffarian D, Rimm EB, Herrington DM. Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. Am J Clin Nutr 2004;80:1175-84. [Abstract/Free Full Text]

5. Knopp RH, Walden CE, Retzlaff BM, et al. Long-term cholesterol-lowering effects of 4 fat-restricted diets in hypercholesterolemic and combined hyperlipidemic men. The Dietary Alternatives Study. JAMA 1997;278:1509-15. [Abstract]

6. Retzlaff BM, Walden CE, Dowdy AA, McCann BS, Anderson KV, Knopp RH. Changes in plasma triacylglycerol concentrations among free-living hyperlipidemic men adopting different carbohydrate intakes over 2 y: the Dietary Alternatives Study. Am J Clin Nutr 1995;62:988-95.[Abstract]

7. Knopp RH, Zhu X, Bonet B. Effects of estrogens on lipoprotein metabolism and cardiovascular disease in women. Atherosclerosis 1994;110(suppl):S83-91.[Medline]

8. Mittendorfer B, Patterson BW, Klein S. Effect of sex and obesity on basal VLDL-triacylglycerol kinetics. Am J Clin Nutr 2003;77:573-9.[Abstract/Free Full Text]

9. Barrett-Connor E, Giardina EG, Gitt AK, Gudat U, Steinberg HO, Tschoepe D. Women and heart disease: the role of diabetes and hyperglycemia. Arch Intern Med 2004;164:934-42. [Abstract/Free Full Text]

10. Aikawa K, Retzlaff B, Fish B, et al. Dyslipidemia of insulin resistance and obesity: gender differences. Circulation 2002;106(suppl 2):II-75 (abstr 377).

11. Walden CE, Retzlaff BM, Buck BL, Wallick S, McCann BS, Knopp RH. Differential effect of the National Cholesterol Education Program (NCEP) Step II diet on HDL cholesterol, its subfractions, and apoprotein A-I levels in hypercholesterolemic women and men after 1 year: the beFIT Study. Arterioscler Thromb Vasc Biol 2000;20:1580-7. [Abstract/Free Full Text]

12. Knopp RH, Retzlaff B, Fish B, et al. Effects of insulin resistance and obesity on lipoproteins and sensitivity to egg feeding. Arterioscler Thromb Vasc Biol 2003;23:1437-43. [Abstract/Free Full Text]

This book is great reading if you want to learn more!

SATURATED FAT MAY SAVE YOUR LIFE by Bruce Fife, N.D.

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