Saturated Fats, Cholesterol, and Heart Disease

So, last Wednesday I made a Coconut Creme Pie and brought it into work. No surprise, it was completely consumed with other coworkers on the waiting list for slices that were disappointed. What was surprising was a couple of the consumers commented on how bad the pie must be for their bodies. I assured them that I used no additives and kept the ingredients as fresh as possible. I admit that there were some trans fats in this particular pie because I was unable to get graham crackers without partially hydrogenated oils. It turned out that they were concerned mainly about the coconut. One of my coworkers who was watching his cholesterol levels said, "It's high in cholesterol!" I assured him that as a plant product, it was impossible for coconut to have cholesterol. Then he said, "Well, it's high in saturated fat then."

Ah, saturated fat. The most maligned and misunderstood "bad" food in the last thirty years. During the last year, I've been trying to figure out why everyone thinks saturated fat is evil and I have been unable to discover any evidence that there is evidence that saturated fats are bad for you. In fact, quite the opposite. I'll take this space and discuss briefly (although it might seem long to you) saturated fats, polyunsaturated fats, cholesterol, and the misconceptions we've been brought up with. I'll touch briefly on trans fatty acids too, but that topic is so nasty that it really deserves it's own article along with the possible manipulation of the American diet by food oil companies. Okay, back to saturated fat.

Something that doesn't help is that saturated fat is specifically called out on nutrition labels on food products as well as a Daily Value Percentage. This makes it seem that we need to limit the intake of saturated fat but not monounsaturated or polyunsaturated. This implies that saturated fats are worse than the other two fats and that is not the case.

A little background first:
Fats are comprised of fatty acids which are long chains of carbon atoms with hydrogen atoms hanging off them:
     H H H H H H H H H H H
COOH-C-C-C-C-C-C-C-C-C-C-C-H
     H H H H H H H H H H H
(lauric acid)
(This molecule can be written as CH₃(CH₂)₁₀COOH.) If all the carbons between the carboxyl (COOH) group and the methyl (CH₃) group have two hydrogen atoms attached to them then the fatty acid is considered to be saturated. A saturated fatty acid is more or less straight (in reality the carbons zigzag a bit, but the overall chain is straight). This causes the fatty acid to have a high melting point. The longer the chain, the straighter the chain, the higher the melting point. That means most saturated fats are solid. In addition, the carbon single bond is quite strong resulting in a molecularly stable fatty acid.

Unsaturated fats refer to fats containing fatty acids that do not have as many hydrogens attached as is possible. Instead of bonding to hydrogen, one or more carbon atoms form a double bond with the next carbon:
     H H H H H H H     H H H H H H H H
COOH-C-C-C-C-C-C-C-C=C-C-C-C-C-C-C-C-C-H
     H H H H H H H H H H H H H H H H H
(oleic acid)
This is a monounsaturated fatty acid because it has only one carbon double bond. This particular fatty acid (oleic acid) has a double bond in the ninth position from the methyl (CH₃) group making it an omega-9 fatty acid. The majority of olive oil's monounsaturated fat is comprised of oleic acid. The double bond causes a bend in the chain (away from the missing hydrogens) so that the chain is no longer straight. This lowers the melting point and causes unsaturated fats (like olive oil) to be liquid at room temperature. Also every double bond in a fatty acid "weakens" the structure.
When a fatty acid has more than one carbon double bond, then it is considered polyunsaturated:
     H H H H H H H     H     H     H H
COOH-C-C-C-C-C-C-C-C=C-C-C=C-C-C=C-C-C-H
     H H H H H H H H H H H H H H H H H
(alpha-linolenic)
This particular fatty acid (alpha-linolenic acid) has the first double bond in the third position from the methyl (CH₃) group making it an omega-3 fatty acid. This fatty acid is found most commonly in flaxseed oil and salmon. Because of the three double bonds, this fatty acid is fragile and very sensitive to light and heat. Also, because of the three double bonds, this fatty acid curves back on itself and has a very low melting point.

When exposed to free radicals (molecules with unpaired electrons that are highly reactive), polyunsaturated fatty acids can undergo a process called lipid peroxidation which results in the polyunsaturated fatty acid to release additional free radicals. Lipid peroxidation has been directly linked to artherosclerosis (the constriction of the arteries due to build up of a plaque composed of fats, cholesterol, and other substances) and coronary heart disease (artherosclerosis of the coronary arteries that lead to the heart). Free radicals have little or no effect on the more stable monounsaturated and saturated fats.

It is commonly believed that the build up in the arteries is predominantly saturated fat and cholesterol. This is an inaccurate or incomplete statement. The plaque in the arteries varies from subject to subject, but it has been demonstrated that 3/4 of the fatty acids present in arterial plaque is unsaturated. [1] Also, cholesterol's role in the body is ignored when discussing artherosclerosis. The plaque formed in the arteries does contain substantial amounts of cholesterol, but probably because cholesterol is used as a healing agent. The damaged interior artery walls are patched up with cholesterol and then additional plaque builds up and more cholesterol is used to patch up the walls. The cholesterol is most likely not a cause of the plaque build up, but instead a body reaction to the plaque. The fact that no cholesterol is found sticking to the interior vein walls (where cholesterol concentration is the same as in the arteries) as you would expect if you were to believe the predominantly advertised theory that cholesterol causes circulatory disease. [2]

This brings us to the common belief that saturated fat increases the blood LDL cholesterol levels which in turn cause artherosclerosis. Low Density Lipoproteins (LDL) carry cholesterol from the liver to the tissues while High Density Lipoproteins (HDL) carry cholesterol in the blood back to the liver to be broken down. The buzz words "good" cholesterol and "bad" cholesterol have been used to label HDL and LDL, respectively. The belief that saturated fat lowers HDL in the blood is backed by several scientific studies, but there are also a number of studies that show that saturated fat intake can result in an increase in HDL as well. [3]Currently, there is no conclusive proof that saturated fat intake can be correlated to change in HDL/LDL ratio in the bloodstream.

An even more interesting fact is that the claim that LDL and HDL levels play an important part in heart disease and that there is a fight between "good" and "bad" cholesterol is short on supporting evidence (but long on media support). There seems to be as much scientific data that populations with high incidents of coronary heart disease tend to have higher levels of HDL (so-called good cholesterol). In addition, low levels of HDL do not correlate to an increased risk for coronary heart disease. Most interesting of all, is a study of people who have genetically caused reduced levels HDL do not have a higher risk of coronary heart disease. [4] Studies across several countries with similar HDL-LDL levels resulted in very different incident rates of heart disease. If the theory that HDL-LDL leads to heart disease is to be true, then a more consistent death rate from the disease would have been evident in these countries. It has also been shown that cholesterol level in the blood stream has no correlation with heart disease. In fact, over 80% of people who suffer heart attacks, do not have elevated cholesterol levels. [5] In addition, only 30-40% of people with artherosclerosis have elevated cholesterol levels. [6] It seems that cholesterol is neither a good indicator nor a risk factor for heart disease. (Note: A very small percentage of people have a genetic illness called hypercholesterolemia which interferes with their ability to matabolize cholesterol. People with this genetic condition do have to watch blood cholesterol levels.) [7]

So, what is the next most likely candidate for leading to heart disease? Lipoprotein (a) or Lp(a) has been pointed to as a coronary heart disease risk factor. [8] Although research is incomplete, early findings have been strongly suggesting that Lp(a) contributes to and promotes atherosclerosis. Evidence currently points to trans fatty acids as a major increaser of Lp(a) levels. What's ironic is that saturated fats have been linked to lowering Lp(a) levels! [9]

So, what are trans fatty acids? In polyunsaturated fatty acids, the chains naturally are found to all bend in the same direction. In chemistry this is referred to as cis. If the bends alternate, then this is referred to as trans.
     H H H H H H H     H H H H     H H
COOH-C-C-C-C-C-C-C-C=C-C-C=C-C-C=C-C-C-H
     H H H H H H H H H H     H H H H H
(trans-9,12,15-octadecatrienoic acid)
Trans fatty acids are created through partial hydrogenation of fats (natural or chemical). In nature this occurs rarely and results in very small amounts of trans fatty acids. In our supermarkets, this is a common place fatty acid. It was discovered that if you partially hydrogenated a fatty acid, about half of the fats would have bends going the other way (not in the same direction: cis), thus straightening out the chain. This causes the fatty acid to have a higher melting point, allowing the public to enjoy solid fats without the saturated fat (which was thought to be bad at the time). Margarine replaced butter, shortening replaced palm oil and lard, and partially hydrogenated soybean oil replaced coconut oil. During the last ten years, a great deal of research has been performed on trans fatty acids and the conclusions are not good. Trans fats (fats made of trans fatty acids) promote artherosclerosis and other cardiovascular dieases and increase the risk factor for cancer. In addition, trans fats have been found to replace necessary saturated fats in fat cells resulting in an unusable substance taking the place where a fuel and nutrient source should have been. This leads to the body increasing capacity of fat cells in order to maintain fuel and nutrient storage levels. Trans fats are also unstable and may lead to promotion of free radicals in the human body (for the same reasons that polyunsaturated fats do).

So, now we have discussed how saturated fats do not cause directly or indirectly heart disease, cholesterol is not an indicator or risk factor of heart disease, polyunsaturated fats should be reduced in the diet, and trans fats are to be avoided completely. (Pretty much the opposite of what the media and food oil producing companies tell us.) But, I haven't discussed any benefits of saturated fats.

Before I get into that, I want to mention that although a reduced polyunsaturated fat intake is recommended, there are two families of essential fatty acids that we should intake: omega-3 and omega-6. These are polyunsaturated fatty acids where the double bond is three or six carbons from the methyl group. About 1-2% of the calories you intake in a day should be omega-3 and about 2-3% should be omega-6. Too much omega-6, however, can limit your body's ability to use omega-3 fatty acids. Omega-3 fatty acids can be found in fish, flaxseed, walnut, and unprocessed soybean oil (the processing that removes color and oil from soybean oil pretty much destroys all the linolenic acid in it).

In a past article, I've mentioned that I cook predominantly with olive oils and butter. Here's why: olive oil is high in monounsaturated fat. In fact it is less than 10% polyunsaturated. Butter is less than 4% polyunsaturated and contains a large amount of heathful substances. These include naturally occuring vitamins (A, D, E, and K), small amounts of linoleic (omega-6) and linolenic (omega-3) acids, butyric acid (demonstrated anti-tumerigenic properties and a major fuel source for intestines), lauric acid (anti-microbial and anti-viral), glycosphingolipids (protects against intestinal infections), conjugated linoleic acid (strong anti-cancer properties and helps prevent weight gain; found only in butter and milk from grass-fed cows), lecithin (assists in metabolising cholesterol and fat components), selenium (aids vitamin E as an antioxidant; butter is one of the richest selenium food sources available), and cholesterol. It might seem weird to list cholesterol as a benefit, but cholesterol is a precursor to vitamin D and many hormones as well as an antioxidant and the body's primary repair substance. Consuming cholesterol also contributes to intestinal wall health. Ingesting cholesterol on a regular basis has been shown to not increase blood cholesterol levels because the body reduces its natural production and increases cholesterol metabolism to compensate.

It should also be noted that the small amount of ingested cholesterol can hardly be noticed in the large amounts of cholesterol flowing in your blood stream. For example, if you are capable of intake half of the cholesterol you consume daily (let's say 150 milligrams of 300 milligrams consumed) and you compare that to the amount of cholesterol in the blood (150 mg/dL), then you'll find that of the 7500 mg of cholesterol in your blood (150 mg/dL * 10 dL/L * 5 L/human) you've added only another 150 milligrams (assuming your body is even capable of intaking 50% of the cholesterol you've ingested). A healthy body can easily throttle back cholesterol production and increase metabolism to absorb the additional cholesterol intake.[3]

1. Felton CV, et al; Dietary Polyunsaturated Fatty Acids and Composition of Human Aortic Plaques. Lancet, 1994.

2. Cranton EM and Frackelton J; Free Radical Pathology in Age-Associated Diseases. Journal of Holistic Medicine, 1984.

3. Enig M; Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol; Bethesda Press, 2000.

4. Smith R and Pinckney E; Diet, Blood Cholesterol, and Coronary Heart
Disease: A Critical Review of the Literature. Vector Enterprises, 1991.

5. Rowland D; The Nutritional Bypass. Heath Naturally Publications, 1995.

6. Reiser R; The Three Weak Links in the Diet-Heart Disease Connection. Nutrition Today, 1979.

7. Byrnes S; Diet and Heart Disease: It Is Not What You Think. Whitman Publications, 2001.

8. Garrison J and Somer E; The Nutrition Desk Reference; Keats Publishing, 1995.

9. Enig M; Fat Facts; Price-Pottenger Nutrition Foundation Journal, Winter 1998.