Dietary Fat; what to eat and what to avoid.

Fat has gotten a bad name in recent years. This is because 68% of Americans die from just three conditions related to obesity: heart disease (43.8%), cancer (22.4%) and diabetes (1.8%). Contrast that with death rates from heart disease (1 in 7) and cancer (1 in 30) in 1900 and you can see we have an epidemic. Can we know that obesity is related to eating fat? I will go into that later. Suffice it to say that from the Surgeon General to the man on the street, people are more aware than ever of the relationship between disease and fat consumption. As a result, hundreds of "non-fat" and "low fat" food products are now available, yet people are fatter than ever. What's happening? Before answering that question, I want to provide an overview of the different kinds of fat and what is good or bad about them.

Fats of animal origin like meats, butter, cheese and eggs are composed primarily of saturated fats and cholesterol. (Fruits and vegetables don't make or contain cholesterol but they may contain saturated fats). Saturated fats can be used to provide calories for our energy needs. Cholesterol can also be used to make important hormones but since your liver already makes enough cholesterol to meet your needs, dietary cholesterol is not necessary for most people. The advantage of saturated fats and cholesterol is that they are fairly stable so they don't spoil as easily as unsaturated fats. The primary disadvantage of cholesterol and saturated fats is that they are solid at body temperature. More on that later.

Fats of vegetable origin, especially seeds, are our primary source of unsaturated fatty acids. These include all the vegetable oils such as olive, canola, peanut, sesame, safflower, corn oil, etc. Unsaturated fats are necessary to cell membranes and other important structures. We must have certain unsaturated fatty acids to live. For that reason, these unsaturated fatty acids are called "essential". These include omega-3 and omega 6 fatty acids. The richest source of omega-3 fatty acids is cold-water fish such as salmon and sardines. The biggest disadvantage of unsaturated fats is that they spoil easily if exposed to light, heat and oxygen.

What does saturated, unsaturated, polyunsaturated and mono-unsaturated mean? What are omega-3 and omega-6 fatty acids? To understand that, we must look at the structure of the fatty acids. A fatty acid is a chain of carbon and hydrogen molecules bonded to each other and to a carbon, oxygen and hydrogen (carboxyl) group at one end. The carboxyl end is attracted to water and the rest of the chain is repelled by water. The length of the chain (number of carbons) makes one fatty acid different from another. For instance butyric acid, found in butter, has a 4 carbon chain while fish oils and brain tissue contain 24 carbon chains. The carbons always come in pairs.

The carbons are bonded to one another by sharing electrons. You can think of this as similar to holding hands. The carbon connects to the carbons in front and behind by holding hands. Unlike us, carbons have 4 "hands" so each of the other hands is holding a hydrogen. When each of the carbon bonds is connected to a hydrogen, the fat is called "saturated". When one or more carbons lets go of its hydrogen and grasps the adjacent carbon with both hands, it is called "unsaturated". A fat with a single unsaturated bond is called monounsaturated (mono means one). An example of a monounsaturated fatty acid is olive oil. A fat with several unsaturated bonds is called polyunsaturated (poly means many). Examples of polyunsaturated oils include safflower, sunflower, corn oil, etc. The most highly unsaturated oils are sometimes called superunsaturated. Examples of these are the fish oils, flax and hemp seed oils.

Why do we need unsaturated fatty acids in our diet? The reason is that though unsaturated fatty acids are needed to make cell membranes and other important structures, we and unable to make all of them ourselves. Our bodies can insert double bonds only after the 7th carbon. We can't create omega-3 or omega-6 fatty acids ourselves. We must eat these unsaturated fatty acids or suffer from a host of diseases and die. The particular unsaturated fatty acids that we cannot make ourselves are linoleic and alpha linolenic acid. Linoleic acid has two double bonds, the first one being in the sixth position from the end (called omega-6 because omega means "end"). Variations on linolenic acid are gamma linolenic acid (GLA), which has 3 double bonds and arachidonic acid, which has 4 double bonds. GLA is found in borage hemp and evening primrose oil. Arachidonic acid is found in animal products. Alpha linolenic acid has 3 double bonds, with the first one being just 3 carbons from the end, hence this group are called omega-3 fatty acids. Variations on omega-3 fatty acids include EPA, which has 5 double bonds and DHA, which has 6 double bonds. EPA and DHA are found in fish oils (and surprisingly enough, snake oil, which vindicates the snake oil salesman of the past).

What functions do these essential fatty acids perform? Essential fatty acids (EFAs) are a required structural component of all cell membranes, including the organelles within cells, nerve sheaths and red blood cells. EFAs are not only flexible, allowing red blood cells to fold to fit into capillaries, they have specific bioelectric properties that allow them to assist in the generation of life force and transmission of nerve impulses throughout the body. EFAs are also required to make hormone-like substances called prostaglandins (more on that later).

Deficiency symptoms of linolenic acid include:
Eczema-like skin eruptioins
Loss of hair Liver degeneration
Behavioral disturbances
Kidney degeneration
Dry skin
Susceptibility to infection
Poor wound healing
Sterility in males
Miscarriage in females
Arthritis pain
Cardiovascular disease
Growth retardation

Deficiency symptoms of alpha-linolenic acid include:
Growth retardation
Weakness
Impaired vision
Learning disabilities and lack of coordination
High triglycerides
High blood pressure
Sticky platelets (increases risk of stroke and venous thrombosis)
Inflammation
Edema
Dry skin

What are prostaglandins? Prostaglandins are hormone-like substances that the body uses to produce and control inflammation, control the tone of the muscles in blood vessel walls, regulate sodium retention or excretion and control the stickiness of platelets (the cells involved in blood clotting). Some prostaglandins increase inflammation, blood vessel contraction, sodium retention and platelet stickiness while other prostaglandins reduce inflammation, relax the blood vessels, excrete sodium and make the platelets less sticky. The prostaglandins which increase the risk of heart disease, high blood pressure, stroke, arthritic pain and edema are made from the fatty acids found in red meats. The prostaglandins which reduce the risk of heart disease, high blood pressure, stroke, diabetes, arthritic pain and edema are made from the fatty acids found in fish oils, flax seed, hemp seed, borage oil and evening primrose oil.

What about saturated fatty acids? Do we need them? They are called saturated because they every carbon in the chain is connected to two hydrogens, thus the carbon is saturated with hydrogens. Saturated fatty acids containing less than 16 carbons are used to provide energy. The shorter the fatty acid chain (fewer carbons), the faster it "burns" to produce energy. Our bodies use saturated fatty acids containing 16 or 18 carbons to make energy, construct membranes or make unsaturated fatty acids. Our bodies cannot convert saturated fats into essential fatty acids. One of the observable characteristics of saturated fatty acids (SFAs) is their tendency to stick together and become solid at room temperature. Short-chain SFAs (up to 8 carbons long) are liquid at room temperature and are thus called oils. Up to 10 carbons long, SFAs are liquid at body temperature. Some short-chain SFAs are found in butterfat, palm kernel oil and coconut oil. Longer chain fatty acids (12 carbons or more) are solid in your body. Next time you fry a hamburger, look in the pan after it cools and imagine those hard, white fats in your bloodstream. A little is fine because you can convert it to energy and saturated fats are also used in making cell membranes. A lot can be a problem. Long chain saturated fatty acids are found most abundantly in beef, lamb, pork and dairy products. Some short-chain fatty acids have beneficial effects on health. Butyric acid (a 4 carbon chain) feeds the friendly bacteria in our intestines while Caprylic acid (an 8 carbon chain) inhibits the growth of candida albicans and other yeasts in our intestines.

What about cholesterol? What is it and what does it do in the body? Cholesterol is a hard, waxy fatty substance with a melting point of 300 degrees F. Because it has such a high melting point, the body uses it to stiffen membranes and other structures. The body also makes all steroid hormones out of cholesterol, including estrogen, progesterone, pregnenolone, testosterone, estradiol, DHEA, cortisol, aldosterone and glucocorticoids. Vitamin D and bile salts are also made from cholesterol. Cholesterol is secreted in the skin, preventing it from drying out. As you can see, a certain amount of cholesterol is essential to life.

How much cholesterol do I need? You don't need to eat cholesterol because your body will make enough. If you eat more cholesterol, your body will produce less. If you eat less, it will produce enough for your needs. For persons at risk of coronary artery disease, the American Heart Association and National Cholesterol Education Project recommend limiting cholesterol intake to under 300 mg per day. In North America, the average adult consumes 800 mg per day of cholesterol in the form of eggs, meats and dairy products. Americans who consume these foods have death rates from cardiovascular disease 4 times greater than that of strict vegetarians. This is not to say that you should never eat meat, eggs or dairy products, just that you should eat them in moderation. Persons with very low cholesterol levels may be at higher risk of cancer. This may be due to lower levels of fat soluble anti-oxidant vitamins A and E being delivered to the tissues. About 30% of people are sensitive to dietary intake of cholesterol. That is, the more cholesterol they eat, the higher their blood levels become. For the other 70% however, the majority of cholesterol is made by the body from excess calories, especially simple sugars. The reason for converting sugar to cholesterol is that too high a blood sugar level is dangerous (as in diabetes) so your body converts excess calories into cholesterol for safer storage. This simple fact can account for the astounding rise in levels of obesity since the low-fat and no-fat "diet" foods became so popular. These foods contain high amounts of sugar which the body converts to cholesterol. Unfortunately, the body cannot break down the cholesterol we consume or make ourselves. We can only get rid of cholesterol by excreting it in the stool. Excretion requires fiber to bind and trap the cholesterol to carry it out in the stool. Without adequate fiber, up to 94% of the cholesterol will be re-absorbed. Dietary fiber can also prevent cholesterol from being absorbed in the first place. Thus a high-fiber diet is one of the best ways to lower high blood cholesterol levels. Another way to lower cholesterol levels is by lowering stress. The body produces more cholesterol when we are under stress, possibly to create more raw material for the manufacture of stress related steroid hormones.

What do blood tests for cholesterol mean? Blood tests measure total cholesterol and also component sub-fractions of the total, HDL, LDL and VLDL cholesterol. A total cholesterol over 200 is excessive and greater than 240 is considered dangerous. The average heart attack patient measures 244mg/dl. A greater predictor of heart attack risk may be having HDL levels that are too low. The ideal ranges of HDL are above 50 mg/dl and below 35 is dangerously low. HDL stands for high density lipoprotein. Its function is to gather excess cholesterol from the arteries and other tissues and bring it to the liver where it can be converted into bile salts for excretion in the stool. HDL levels are increased by aerobic exercise, eating olive oil and drinking red wine or green tea.

What are trans fats? Trans fats are found in margarine's, shortenings and many prepared or packaged foods in which vegetable oils have been hydrogenated. Trans fats don't occur in nature. They are made from unsaturated oils that have been heated to produce a structure that is stiff and inflexible. Normally, unsaturated fats are in the cis configuration, which is a flexible molecule. Trans fats have been twisted to become stiffer and straighter. When these stiff molecules are incorporated into cell membranes, those structures become stiff as well. Why is this important?

Trans fatty acids;
Interfere with essential fatty acids.
Increase blood cholesterol levels by 15% and triglyceride levels by as much as 47%.
Raise lipoprotein A, a strong risk factor in atherosclerosis (hardening of the arteries)
Lower the efficiency of immune system B cells
Decrease testosterone and increase abnormal sperm (in animals)
Interfere with pregnancy
Correlate with low birth weight in humans
Lower the quality of breast milk
Decrease insulin response (bad news for diabetics)
Alter the activities of the liver enzyme ((P-448/450) that metabolizes carcinogens Alter membrane transport and fluidity
The increased rate of cancer death is strongly associated with the increased use of hydrogenated trans fatty acids in the American diet.

Why do manufacturer's make and use trans fats in their products? They are more stable and thus give their products a longer shelf life. Unfortunately, these altered molecules contribute to a host of diseases.

Which oils should I buy? Extra virgin olive oil is the only oil commonly available that has not been overheated, purified, chemically treated and disinfected to the point of being stripped of its healing qualities and adulterated with altered molecules such as trans fatty acids. The wonderful oils found in seeds and grains such as canola, sunflower, safflower, are frequently degummed, filtered, refined, bleached and deodorized and heated to around 464 to 518 degrees F for 30 to 60 minutes during processing. Some oils are extracted using a solvent such as hexane or heptane (gasoline) at 131 to 149 degrees F, then the solvent is evaporated off at a temperature of about 302 degrees F. It is possible to buy mechanically (expeller) pressed oils that are sold unrefined in dark glass with the pressing date on the label to ensure freshness. Such oils are difficult to obtain and may require mail order. The simplest way to get plenty of high-quality oil in your diet is to eat fresh-ground flax seed, pumpkin seeds, sesame or sunflower seeds and fresh cold-water fish. For oil to dip your bread or sautˇ, use extra virgin olive oil.

Which oil should I use in cooking? All oils are damaged by heat and light and exposure to air. Heated oils generate a number of toxic compounds, including trans fatty acids discussed above. The best policy is to never fry your foods and to use oils that can take pretty high heat when baking, boiling or sautˇing. Cooking vegetables in a wok or pan with a little oil can be fairly safe because the vegetables "sweat" and the oil floats on the vegetable water. The best oil to use in cooking is clarified butter (called ghee in Indian cuisine) or tropical oils (palm kernel or coconut) that have not been partially hydrogenated. Peanut and sesame oils can take fairly high heat before becoming damaged but unfortunately, most commercially available seed oils have already been exposed to extreme heat for prolonged periods during manufacture. Extra virgin olive oil is the only oil commonly available that still has its nutrient value intact and being a monounsaturate, has only one open bond on the carbon chain that can be damaged by exposure to light, heat and oxygen.

To learn more about incorporating healthy oils in your diet, check out the recipes in this section.

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