Health and Nutrition

Fats are the most concentrated source of energy available to man. A gram of fat (1 tsp. = 5 grams) has 9 KCAL, whereas a gram of protein and a gram of carbohydrates each have 4 KCAL. Some people believe that the so-called "good" fats such as olive oil have fewer calories. In truth, all fats have the same energy content. Excess fat consumption, or simply eating too many calories, signals fat deposition in adipose tissue regardless of the source. If we observe the USDA's Food Guide Pyramid, fats are positioned at the top, indicating limited intake. Health professionals recommend that fat consumption should be limited to no more than 30 percent of total calories. It is absolutely essential that some fats and oils be included in the diet. They are not only a source of energy, but the fatty acids, linoleic and linolenic, are essential to growth, maintenance of cellular and subcellular membranes and are precursors of a powerful family of regulators that affect physiology. The most common fatty acids in the American diet are palmitic and stearic (both saturated) and palmitoleic and oleic (both mono-unsaturated).

It has been established that there is an increased risk of heart disease as saturated fat consumption increases. Saturated fats raise total blood cholesterol levels and low density lipoprotein cholesterol levels (LDL), both of which have been associated with increased risk for heart disease. The food industry and consumers have been profoundly affected by these findings. In the mid- to late 1980s, the food industry stopped using highly saturated fats of animal origin for deep-fat frying, replacing them with hydrogenated vegetable oils.

Cholesterol, a waxy substance synthesized from a two-carbon fatty acid, acetic acid, is well established as an independent risk factor for heart disease. This waxy substance is a major component of arterial plaque. Blood flow can eventually be blocked and a heart attack can result.

Cholesterol, however, is also required by every cell in the body as it is the major component of the cell membrane. Cholesterol is also synthesized by the human body and we adjust our rate of synthesis to dietary intake-if we consume more cholesterol, our bodies simply make less and vice versa. Dietary cholesterol, therefore, is one of the least important variables affecting blood cholesterol levels.

Trans fatty acids are the trans isomers of unsaturated fatty acids. Most naturally occurring unsaturated fatty acids are found in the "cis" form. "Cis" and "trans" refer to the position of the hydrogen atoms around the double bonds of the fatty acids. When the hydrogen atoms are on the same side of the chain, they are in the "cis" position; those on opposite sides of the chain are in the "trans" position. Oleic acid is an example of a "cis," while elaidic acid is an example of a "trans." "Cis" fatty acids have a kink in them and "trans" fatty acids are straight.

If the triglyceride being examined has a high level of trans fatty acids, they will pack together tightly and solidly forming hard crystals. Harder fats have a higher melting point. The melting points of trans fatty acids are closer to the saturated form than the unsaturated "cis" form.

The majority of the trans fatty acids in the diet are those produced during hydrogenation. When oils are partially hydrogenated from polyunsaturated to monounsaturated, trans fatty acids result. Saturated fat is a much more stable molecule than an unsaturated one; therefore hydrogenation increases the stability of a fat.

Trans fatty acids are not simply the product of man's chemistry. They also occur naturally and may be found in butter, for example. Fats from ruminants, such as cattle and sheep, commonly contain them. Even though there is debate over the average consumption of trans fatty acids (estimates range from 7.6 to 15.2 grams per person per day in the U.S.), there can be no argument that there are many foods that have high levels of trans fatty acids. If the scientific community cannot agree on the quantity of trans fatty acids being consumed, there is an even greater debate about whether these compounds pose potential health risks. Researchers have linked trans fatty acids to everything from heart disease to low birth weights, while other researchers claim the data does not support such claims.

If trans fatty acids are a concern, manufacturers have options to reduce the number of trans fatty acids in their products. In some applications, manufacturers can use a naturally saturated oil, such as cottonseed oil, instead of hydrogenating a less saturated oil, such as soybean oil, thus avoiding the formation of trans fatty acids. If hydrogenation is needed to achieve a certain functionality, hydrogenating a naturally saturated oil will produce fewer trans fatty acids. Also, if a vegetable oil is hydrogenated to total saturation (less than 3.0 IV), there are no trans fatty acids. Some manufacturers use fully hydrogenated cottonseed oil blended with a highly unsaturated oil to arrive at a blend with near zero trans fatty acids.

The range of oil compositions is virtually unlimited. Oil refiners, with their resources of oil specialists, laboratories and technical support, can help manufacturers develop oils and oil blends with virtually any characteristics required for their products, from long-lasting to low-fat to low in trans fatty acids. Refiners also are excellent resources for information on the latest new oils and developments in oil science and technology.