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Dietary Fat Revisited:
A Positive Update on an Old Adversary

By Michelle Punj
Nutrition Intern at Red Mountain Spa

Many Americans still tend to fear dietary fat, a likely carryover from the low-fat diet craze of the ‘80’s. However (and undeniably), key components of fat – namely essential fatty acids – are nutrients we must consume to sustain proper body functions (absorption of fat soluble vitamins, blood pressure regulation, immune support etc.). Unfortunately, the fat found in Chocolate Fudge Brownie ice cream does not hold the same nutritional benefits as the fat found in salmon or walnuts. Consequentially, health-conscious consumers need to differentiate between dietary fats in order to choose those that are genuinely required (i.e. essential) and (potentially) may have the greatest positive impact on overall health.

Fat molecules are composed of three essential fatty acids bonded to a molecule of glycerol. Together, they are called triglycerides in reference to the trio of fatty acids. When triglycerides are broken down into their constituents parts, glycerol is frequently converted to glucose and used for energy. Fatty acids are also a lucrative energy source containing approximately 9kcal per gram (compared to 4 kilocalories per gram of protein or carbohydrate) and are used predominately by the heart and skeletal muscles. In addition, fats are used to digest, absorb and transport fat-soluble vitamins (namely, A, D, E, and K) in the body.

Since fatty acids are the most concentrated form of energy, they are stored in tissue and only burned when other sources of energy are depleted or unavailable to sustain activity. Thus, fat burning increases with physical activity. However, the percentage of fat burned will vary with exercise intensity. Optimum exertion (supportive of maximum fat-burning efficiency) is a uniquely individual function determined by respiratory gas exchange at ascending levels of physical exertion. At Red Mountain Spa, a test called Metabeat measures the optimal heart rate for burning fatty acids during exercise.

In foods, fats can be found in both plant and animal sources and are classified by their level of hydrogenation. Saturated fats are completely saturated with hydrogen atoms and therefore tend to be solid at room temperature. Examples include butter, meat and dairy products. Since, saturated fats are correlated with increased risk of atherosclerosis and heart disease, the USDA recommends replacing saturated fats with unsaturated fats in order to reduce “bad” cholesterol (LDL) and increase “good” cholesterol (HDL).

Below is a chart of common cooking oils and fats, listed in ascending order of saturated fat concentration expressed as a percentage of total fat content.

Unsaturated fats can be mono-, or poly-unsaturated and are generally found in plant oils. The prefix (mono- or poly-) denotes the number of double bonds in the carbon chain (mono- = a single double bond, ploy- =two or more double bonds). The greater the number of double bonds, the less saturated the fat is with hydrogen atoms making it more liquid at room temperature. Vegetable oils, as an example, are very unsaturated and always liquid when taken out of the pantry. In addition, the configuration of the carbon chain around the double bond can either be cis (on the same side) or trans (on opposite sides).

Monounsaturated fats, found in abundance in canola, olive, peanut and avocado oils, have only one double bond and are currently viewed as healthy alternatives to saturated fat. Over the past decade, published studies have confirmed their ability to lower cholesterol levels and thereby reduce the risk of heart disease. In addition, a study conducted at Ohio State University found that adding half an avocado to a salad increased the absorption of the fat soluble vitamins in dark leafy greens by ten-fold.

Below is a chart listing abundant sources of monounsaturated fatty acids, listed in descending order of monounsaturated fat concentration, expressed as a percent of total fat content.

Polyunsaturated fats have more than one double bond and are found in many nuts and seeds and their oils. These fats also have cholesterol reducing effects when used in place of saturated fats.

Omega-3 fatty acids are polyunsaturated fats found in relatively high amounts in some cold water fish (like salmon, tuna, and mackerel), flaxseeds, walnuts, and to a limited degree in dark leafy greens. The term omega-3 signifies that the double bond in the carbon backbone occurs at the third carbon-carbon bond. Omega-3 acids include alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid, commonly referred to as ALA, EPA, and DHA, respectively. Omega-3’s are essential fatty acids that have been proven to positively effect numerous aspects of health including: increasing HDL levels, stabilizing mood in bipolar patients, decreasing platelet stickiness (thereby reducing the risk of a clot-induced heart attack, stroke, or kidney infarct), improving cognitive function in the elderly, reducing inflammation, and even reducing the age-related decline in respiratory capacity among elderly athletes.

Below is a chart of omega-3 fatty acid content in fish.

Omega-6 fatty acids, which are primarily found in grains, some vegetable oils, poultry and eggs, have a double bond at the first carbon-carbon bond and include: linoleic acid, gamma-linolenic acid, and arachidonic acid. These unique lipids help regulate inflammation, blood pressure, and heart, GI and kidneys functioning. However, medical research indicates that high ratios of serum omega-6 to omega-3 fatty acids are strongly indicative of disease risk. The typical American diet consists of 10:1 to 30:1 omega-6 to omega-3 fatty acids; however, a healthy ratio is less than 5:1. Therefore, consumers would best serve their health-related goals by eating more cold water fish, flaxseed or taking a fish-oil supplement.

Omega-9 fatty acids, like oleic acid, are only of significance if there is a deficiency in either omega-3 and/or omega-6 fatty acids. During a deficiency in other omega acids the body produces omega-9 acids to compensate. Therefore, omega-9 acids are used as an indicator of deficiency.

Hydrogenated fats should be on everyone’s dietary black list. They are made by infusing hydrogen gas into an unsaturated fat in order to remove double bonds. This process increases saturation, solidity at room temperature and consequentially shelf life. Complete hydration transforms unsaturated fats into saturated fats and therefore has the same negative effects. Partially hydrogenated (and therefore partially saturated) oils are used in a variety of products such as deep-fried snack foods, baked goods, margarines, peanut butter, etc. Fully hydrogenated oils are used in shortening products.

Trans-fatty acids have a trans configuration around a double bond which is, unfortunately, a bi-product of hydrogenation. Although they can be found in small amounts in animal fats, they are more highly consumed in hydrogenated fats like margarine and products made from shortening. Trans-fats have a double negative impact on consumer health because they not only raise LDL cholesterol but lower HDL cholesterol thereby increasing total blood cholesterol levels even more than saturated fats. Thus, hydrogenated oils, with both saturated fat and trans fat, should be avoided whenever possible.

Listed below are the current recommendations for total fat and types of fat:

• The USDA recommends that Americans consume up to 30% of total calories from fat. However, the ratio of types of fats consumed can have a profound impact on health – both positive and negative.
• Saturated fat, hydrogenated oils, and trans fatty acids may increase LDL levels and total cholesterol thereby increasing risk of heart disease. Therefore it is recommended to consume no more than 7-10% of total calories from saturated fats. Hydrogenated oils and trans fatty acids should be avoided completely.
• Monounsaturated fatty acids help to lower LDL cholesterol levels and decrease risk of heart disease. Current recommendations are to consume 10-15% of total calories from monounsaturated fats.
• Polyunsaturated fats in place of saturated fats decrease LDL cholesterol and omega-3 fatty acids can favorably increase HDL. It is recommended to consume 10% of total calories from polyunsaturated fats.

Recommendations: Since it is near impossible to keep tract of our total fat intake (much less types of fat), most people will benefit, healthwise, by 1. consciously reducing their intake of hydrogenated oils and saturated fat (check the labels), and 2. increasing consumption of fish, flaxseeds, almonds, and other foods containing elevated levels of omega-3 fat.