Fatty Acid Basics

November 2001

When people speak of fats or when nutrition reports are made to the general public, they typically speak in terms of fat — a healthy fat, a saturated fat, etc. But much of the functionality and health implications of these compounds are actually due to the components that define or characterize those fats, the fatty acids.

By the chemistry book
The term “fat” refers to what is commonly called triglycerols — although the correct chemical nomenclature is triacylglycerols (TAGs), because triglyceride literally means three glycerol moieties. These are a form of lipids comprised of three fatty-acid molecules attached to a glycerol backbone. The positions on the glycerol backbone are designated sn-1, sn-2 and sn-3 (stereospecific numbering). Fat also can take the form of a diacylglycerol (DAG), which contains one glycerol and two fatty acids, and a monoacylglycerol, which contains one glycerol and one fatty acid.

The fatty acids are made up of chains of carbon atoms with a terminal carboxyl group that can bond to one of glycerol’s hydroxyl groups. The number of carbon atoms typically varies from between four and 26 carbon atoms arranged in a straight chain. Often, fatty acids are categorized by chain length: those called short chain have less than 10 carbon atoms, medium chain have 10 to 14 carbon atoms, and long chain have more than 14 carbons. Generally, naturally occurring fatty acids have an even number of carbons in the chain, but some exceptions occur. For example, valeric acid, a five-carbon saturated fatty acid, occasionally can be found in fermented products and milk fat.

The type of bonds between the carbon atoms also helps define fatty acids. Saturated fatty acids (SFA) contain the maximum number of hydrogen atoms; they contain no reactive double bonds between the carbons. Unsaturated fatty acids contain less than the maximum number of hydrogen atoms, because they have at least one double bond; these fatty acids can be termed monounsaturated, or MUFA, (one double bond) or polyunsaturated, or PUFA, (more than one double bond). Polyunsaturated fatty acids contain a high number of double bonds, making foods with this type of fatty acid more prone to oxidative rancidity.

These double bonds can occur as either cis or trans geometric configurations. In the more-common cis configuration, both hydrogen atoms attached to the carbons with the double bond fall on the same side of the chain, causing a bend and a more flexible molecule. The trans position has the two hydrogens positioned on opposite sides of the chain. This makes the double-bond angle of the trans fatty acid less sharp and the chain more linear, resulting in a more-rigid molecule that packs together easily. Dairy and other animal fats and a few plant fats contain some trans fatty acids, but most come from hydrogenated fats. They consist mainly on the trans isomers of oleic acid, elaidic acid (t9-18:1) and vaccenic acid (t11-18:1).

Hydrogenation removes double bonds and adds hydrogen atoms to the carbon, which transforms liquid oils into solid fats and increases resistance to oxidation. The process randomly inserts hydrogen atoms; partial hydrogenation gives a mixture of polyunsaturated and monounsaturated (both with trans isomers) and saturated fatty acids. As the degree of hydrogenation increases, monounsaturates and trans fatty acids increase, and saturates increase slightly, while the level of polyunsaturates decreases.

Structural themes
All that chemistry about structure of the fat and its fatty acids is important because it affects the fat’s characteristics. “The chemical and physical properties of TAGs are dictated by the chain length and extent of saturation of the associated fatty-acid moieties and the positioning of the fatty acids on the glycerol backbone,” says Robert Wainwright, technical director, Cargill North America Refined Oils, at the company’s C+T subsidiary in Charlotte, NC. “Fats and oils are composed of not just a single TAG, but rather a variety of structures which collectively dictate their unique properties.”

For example, three fatty-acid factors affect melting point: the longer the chain length, the higher the melting point; the greater the degree of saturation, the higher the melting point; and a trans configuration also increases melting point. The melting point of oleic acid (9c-18:1) is 13°C, elaidic acid (9t-18:1) is 44°C, and the saturated fat stearic acid (18:0) is 70°C.

But according to Wainwright, fatty-acid composition alone does not tell the whole functional and nutritional story. “TAG structure — positions occupied by the associated fatty acids — contributes significantly to both properties,” he notes. “For example, consider lard and tallow, both of which have similar fatty-acid compositions; the major fatty acids are palmitic, stearic and oleic. In lard, palmitic acid occurs almost exclusively at sn-2 and oleic at the outside positions, while in tallow the saturates are distributed at the sn-1,3 positions. The unique TAG structure of lard provides a crystal structure that makes it very desirable for bakery items, like pie crusts, that require flakiness.”

The fatty acids also affect digestibility and therefore calorie contribution. Caprenin, a reduced-calorie triglyceride composed of caproic (6:0), capric (10:0) and behenic (22:0) fatty acids, contributes only 5.0 kcal/gram vs. the normal 9.0 kcal/gram. The short-chain caproic and capric acids have lower energy values and the body poorly absorbs behenic acid. Salatrim has a similar composition; it has two short-chain fatty acids, acetic (2:0), propionic (3:0) or butyric (4:0) and one long-chain fatty acid, stearic. This combination yields only 4.5 to 6.0 kcal/ gram.

Stereospecificity, or fatty-acid positioning, also has nutritional implications. “Pancreatic lipase, for example, is highly 1,3 specific; free fatty acids cleaved from the outer TAG positions are often handled differently metabolically from the 2-monoglyceride remnant,” explains Wainwright. “Longer-chain acids, such as palmitic and stearic, tend to be less well-absorbed because of their high melt points and ability to form calcium soaps.”

Essential nutrients
Out of all these different variations, human diets require only two fatty acids — called the “essential” fatty acids — linoleic acid and alpha-linolenic acid. The body cannot synthesize these, and requires them to produce eicosanoids — compounds that help regulate blood clotting, blood pressure, heart rate, immune response and many other biological processes.

Linoleic acid (18:2n-6) is called “omega-6,” or “n-6,” because its first double bond occurs at the sixth carbon from the omega, or methyl (-CH3), end of the fatty acid. Vegetable and nut oils, such as sunflower, safflower, corn, soy and peanut, contain significant amounts, so most Americans have adequate levels of linoleic or omega-6 fatty acids in their diets.

Alpha-linolenic acid (18:3n-3) is an “omega-3,” or “n-3,” fatty acid because its first double bond comes at the third carbon from the omega end. It can be found in flaxseed oil (51% linolenic acid), canola oil (9%), soy oil (7%) and walnuts (7%).

Linoleic acid can be oxidized by the body to produce energy, or converted by enzymes to longer-chain PUFAs such as gamma-linolenic acid (GLA), dihomo-gamma-linolenic acid (DGLA) and arachidonic acid (AA). The body uses the same enzymes to convert alpha-linolenic acid to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), though this is a somewhat inefficient process. Therefore, some experts suggest a direct intake of these two long-chain omega-3s.

Health implications
The USDA’s 1995 Dietary Guidelines for Americans recommends that total fat intake be no more than 30% of total calories. This limits the excess consumption of fat that can lead to obesity, and also helps to limit the negative effects that may occur from excess consumption of some fatty acids. Research shows that certain fatty acids influence the serum levels of lipids and lipoproteins and therefore the incidence of coronary heart disease.

Saturated fatty acids raise total cholesterol mostly due to an increase in low-density lipoprotein (LDL) cholesterol. However, high-fat diets also can increase high-density-lipoprotein (HDL) cholesterol and apolipoprotein A-I. Most research finds that the LDL:HDL cholesterol ratio is greater in diets high in total fat and SFA than in low-fat or PUFA-rich diets.

But, as mentioned, saturated fatty acids come in different chain lengths, and studies show that these do not have the same effect on serum cholesterol. The majority of saturated fats consumed in the United States consist of palmitic acid (16:0), stearic acid, myristic acid (14:0) and lauric acid (12:0). Lauric, myristic and palmitic will raise LDL cholesterol to a fairly high degree. However, research shows that the cholesterol-elevating effect of stearic is much less than that of the other three, and more closely approximates oleic acid’s effect on LDL. Stearic acid may also result in a slight drop in HDL cholesterol compared to unsaturated fatty acids.

Still, nutrition experts give a general recommendation to reduce the amount of saturates in the diet because saturated fatty acids that raise blood cholesterol predominate in a typical diet. Instead, they promote polyunsaturated fatty acids (PUFAs) as a replacement for saturates.
The omega-3 and -6 PUFAs have distinct metabolic properties. The major dietary PUFA is linoleic acid, found in most vegetable oils. Other omega-6 PUFAs, linolenic acid and arachidonic acid (20:4n-6), make up less than 2% of the total dietary fatty acids.

Soybean, canola and flaxseed oils contain relatively high levels of linolenic acid. The long-chain (lc) omega-3 PUFAs EPA (20:5n-3) and DHA (22:6n-3) are found in marine oils, particularly cold-water fish. Research is finding that including marine-derived lcPUFAs in the diet may reduce the incidence of coronary heart disease and stroke, and may have a beneficial effect on other disorders (including dyslexia, arteriosclerosis and asthma). Omega-3 PUFA oils also aid brain and retina development and function.

Trans troubles
In addition to saturated fatty acids’ negative health effects, an increasing body of evidence implicates trans fats in promoting heart disease. According to the American Society for Clinical Nutrition (ASCN) and the American Institute of Nutrition (AIN), Bethesda, MD, “When intake of trans fatty acids (as hydrogenated fat) is compared with that of saturated fat, total and low-density-lipoprotein (LDL)-cholesterol concentrations in blood are lower, but both trans fats and saturated fats increase total and LDL concentrations when compared with cis fatty acids or native unhydrogenated fat.”

Some studies suggest that trans fats may present more of a risk than saturated fats, however the full range of their effects on health and disease is still unknown. However, the ASCN and AIN considers that a reasonably large body of data exists that associates plasma lipid and lipoprotein concentrations, which influence cardiovascular disease, to trans-fatty-acid intake. These appear to raise LDL-cholesterol concentrations and plasma concentrations of lipoprotein-a and to decrease HDL cholesterol.

A hydrogenated fat that is solid at room temperature typically contains 15% to 25% trans fatty acids. Partially hydrogenated oils are liquid at room temperature and have lower trans-fatty-acid levels. Beef and sheep fat and butterfat contain trans levels ranging from 4% to 11%, mainly vaccenic acid. The ASCN and AIN estimate the U.S. per capita consumption of trans-fatty acids is 8.1 to 12.8 grams per day, which represents 2% to 4% of total daily energy intake, the majority (80% to 90%) from hydrogenated vegetable oil.

Because of its use of hydrogenated vegetable fats, margarine has been identified as a major trans culprit. Solid stick margarines contain approximately 19% to 49% trans, but soft “tub” margarines contain only 11% to 28%. “Trans-fatty-acid levels of traditional hydrogenated shortening can range between 14% and 18%; these levels have significantly decreased from levels of 25%-plus in the past,” says Frank J. Flider, of the Rockridge Group LLC consulting group and consultant to the United Soybean Board. “Zero-trans shortenings are also commercially available.” The ASCN and AIN conclude that no real increase of trans fatty acids has occurred in the diet because the increased vegetable fat consumption has been counterbalanced by a decrease in the trans-fatty-acid content of many products. They take the position that consuming a few grams of trans fatty acids per day will only minimally affect serum lipoprotein concentration.

To further complicate the issue, all trans fatty acids may not have the same effect. Elaidic acid may actually be the trans fatty acid with the greatest negative health consequence, while the other types may have little-to-no effect. A study published in a March 1997 issue of the Journal of Nutrition by researchers from the Palm Oil Research Institute of Malaysia, Brandeis University, Waltham, MA, and University Malaya Kuala Lumpur, Malaysia, suggests that elaidic acid, commonly produced during hydrogenation, adversely affects plasma lipoproteins.

Taming trans
Increasing trans via hydrogenation is not a nefarious plot by the food industry to undermine the nation’s health, no matter what the activists allege. Hydrogenation increases oil’s oxidative stability and solids levels and controls the level of saturation. “Increased oxidative stability is important for shelf life and fryer life while increased solids is important for shortening and margarine production,” notes Flider.

However, because of the health implications and resulting consumer demand, food technologists are focusing on reducing the trans content of foods. “The simple answer is that the use of partially hydrogenated oils could theoretically be eliminated, but this would be impractical, nutritionally questionable and costly,” Flider says. “Also, availability of adequate volumes to substitute for oils that are currently hydrogenated would be an issue.” Still, a number of trans-lowering technologies that also preserve functionality do exist.

Blending nonhydrogenated hard fractions with nonhydrogenated or minimally hydrogenated stocks can convey body to the fat. “Typically, such hard fractions are derived from palm or palm-kernel fats, both of these being significantly higher in saturates than the partially hydrogenated components they replace,” notes Wainwright.

Improvements in the hydrogenation process, including temperature, pressure, time, catalyst, methods and starting stock, should decrease trans formation. For example, a new technique, developed by ARS chemist Gary R. List, National Center for Agricultural Utilization Research, Peoria, IL, is called low-trans hydrogenation. This technique uses carbon dioxide for hydrogenation to make a product with less than 10% trans fatty acids, which can be used in margarine and similar formulations.

Interesterification, a chemical reaction that rearranges fatty acids on the glycerol molecule, can decrease the trans-fatty-acid content of processed vegetable oils. “Interesterification can be done as mixtures of oils, such as fully hydrogenated oil and a liquid oil, or by removing some of the saturated fatty acids by running the reaction at low temperatures (directed interesterification),” says Flider. “It can also be done with enzymes, which will affect only certain positions on the glycerol backbone. This process is used commercially to produce zero-trans margarine and shortening oils by interesterifying liquid oils with fully hydrogenated oils.”

Using inherently higher oxidatively stable oils and fats can substitute for partially hydrogenated components. “For instance, nonhydrogenated coconut oil represents a functional alternative to partially hydroenated vegetable oil sprays,” suggests Wainwright. He also points out that many of the identity preserved oils, for example high oleic and/or reduced polyunsaturate sunflower, canola and soybean, “present the possibility to replace traditional varieties with nonhydrogenated oils of superior oxidative stability.” These can be obtained by using some of the following techniques:

• Plant breeding, including mutation techniques, allows traits to be bred in, out or modified, depending upon desired end composition and availability of the trait in available germplasm. According to Flider, this produces non-GMO ingredients, and the technique often is faster and cheaper than genetic engineering. He cites the following disadvantages: it’s applicable only to available germplasm; traits unavailable in crossable species can’t be bred in; multiple gene traits are difficult to modify; levels of expression are usually not as high as can be achieved through genetic engineering; and undesired effects must be bred out.

• TILLING (Targeting Induced Local Lesions In Genomes) is a relatively new technique that does not involve gene insertion, and allows for the controlled screening of mutations, which can ultimately lead to “knockouts” or “knockdowns” of certain traits, genes or enzymes. Flider says that, “by modifying a particular gene or genes in the fatty-acid pathway, the fatty-acid composition can be modified. It can be used in tandem with plant breeding and genetic engineering.”

• Genetic engineering of oilseeds can modify their fatty-acid composition by introduction of genes and traits that may not normally be present in a species. Undesired traits may be reduced or eliminated via anti-sense technology. However, Flider points out that GMOs are commercially unacceptable in certain markets, techniques are expensive, the process takes several years with regulatory oversight, and yields often lag below those of the original varieties.

Wainwright notes that many of the processing options involve higher-cost precursors and/or additional processing; consequently, they typically represent higher-cost alternatives. “Preservation of performance for some of the more demanding applications also presents a challenge,” he says. “Therefore, it is prudent to consider the serving size when such reformulation efforts are undertaken to accurately quantify the magnitude of change required and to appreciate the implications for the nutritional panel.”

Improved soy selections
Soy is one oil currently undergoing a transformation to a “healthier” fatty-acid profile. A compositional target of low in saturated fat and linolenic acid (low-sat/low-lin) and higher in oleic acid was identified in a series of meetings of edible-oil processors and food companies sponsored by the United Soybean Board to identify ideal compositions for soybean oil. According to Flider, “low saturates” were targeted largely for health reasons; dietary guidelines recommend reducing levels of saturates in the diet and, if this could be accomplished in soybean oil, overall saturate consumption could be significantly reduced. “Low linolenic” was chosen to increase the oxidative stability of soybean oil.

“When an oil is partially hydrogenated to increase its stability, the primary purpose is to reduce or eliminate the linolenic,” says Flider. “If the linolenic level is low enough, the need for hydrogenation can be minimized or eliminated in certain cases. Increasing oleic-acid levels will also increase stability, as oleic acid is the most oxidatively stable of the unsaturated fatty acids.”

This low-sat/low-lin oil isn’t intended to replace current soybean oil in all applications. It’s designed for nonfrying and light frying applications that currently use lightly hydrogenated oils, and it may be suitable for other traditional liquid-oil applications. The extent of hydrogenation required, if any, for other applications, such as frying, will depend on functionality test results.

Pilot quantities of approximately 5,000 gal. are expected to be available for testing in early 2002. “Until the oil can be adequately tested and its performance deemed to meet the needs of the food industry, commercialization time targets are premature,” says Flider. “It is hoped and expected that this oil will have demonstrably improved oxidative stability over currently available soybean oil, but the degree of improvement cannot be ascertained without testing.”

Bright ideas from sunflower
The sunflower industry also found that genetics were available to achieve a mid-level oleic range with standard hybridization techniques. This oil composition provided functionality without hydrogenation. “The industry realized that trans-fat labeling would someday be a reality and food manufacturers would be looking for other choices,” says Ruth Isaak, communications director, National Sunflower Association, Bismarck, ND. “The linoleic portion of the fatty-acid profile, while lowered, would still contribute flavor and lowering the already-low saturated fat content would be beneficial too.”

Sunflower oil contains a high level of unsaturated fatty acids (approximately 90%) and a lack of linolenic acid. The primary fatty acids are oleic and linoleic, with the remainder consisting of palmitic and stearic saturated fatty acids. Increasing the oleic (monounsaturated) content gives it higher oxidative stability than conventional sunflower oil, allowing it to be used in frying applications and those with longer shelf life. High-oleic sunflower oil (over 80% oleic acid) was developed commercially in 1985 and now growers produce NuSun™, a mid-range oleic sunflower oil with an oleic content averaging about 60% to 65% and a 9% saturated-fat level.

“It is possible, genetically, to produce sunflower oil with a higher oleic content than we are achieving with NuSun sunflower oil,” says Jerry F. Miller, Ph.D., USDA-ARS Northern Crop Science Laboratory, Fargo, ND. “However, the frying industry has indicated to us that flavor of the food product is compromised when the oleic content is too high, for example, above 80%. So, we have created an oil which gives us the best possible product: high stability in both the stored oil and the fried food product, high flavor quality, no hydrogenation because our oleic content is in the proper high level, and we have very low saturated fat.”

A three-year study performed by Tom Tiffany and Jennifer Gerdes of Decatur, IL-based Archer Daniel Midland’s (ADM) technical service division, compared NuSun to major frying oils, including high-oleic, low-linolenic canola oil and two different iodine-value levels of partially hydrogenated soybean oil. According to the company, NuSun lasted as long as the other oils in the frying process, showed superior taste and exhibited less color development and product darkening.

Canola can too
Canola oil has become popular for its relatively low level of saturated fatty acids, 7% or less, and its significant amounts of essential fatty acids. Plant breeding efforts have further modified the fatty-acid profile of canola oil. Low-linolenic (levels less than 2% vs. 10%) and high-oleic (up to 86%) cultivars have been developed during the past decade in response to the demand for frying oils with low levels of saturated and trans fatty acids and relatively high stability to oxidative changes without the need for hydrogenation.

Canola’s high level of monounsaturates, especially in high-oleic types, may protect against LDL oxidation and reduce arteriosclerosis risk. Canola oil may be a candidate for infant formulas because of its fatty-acid composition, with a high oleic acid level and a good balance between n-3 and n-6 fatty acids (a 18:3 to18:2 ratio of approximately 1:2).

Other healthy choices
Some oil sources have a naturally favorable fatty-acid profile. Walnuts consist of mostly polyunsaturates (76%) and monounsaturates (14%); the ALA content makes up approximately 7% to 9% of the total fatty acids. This composition might lead to specific health benefits, especially against coronary heart disease and stroke.

A study, “Substituting Walnuts for Monounsaturated Fat Improves the Serum Lipid Profile of Hypercholesterolemic Men and Women: A Randomized Crossover Trial,” published in April 2000 in the Annals of Internal Medicine, by researchers from University of Barcelona, Spain and Loma Linda University, Loma Linda, CA, found that incorporating walnuts into the Mediterranean diet reduced serum cholesterol 4.1%, LDL cholesterol 5.9%, and lipoprotein(a) 6.2% more than the base Mediterranean diet. “Walnuts lowered the risk of coronary heart disease by 11%,” says Emilio Ros, M.D., the Barcelona researcher who directed the study. Because the proportion of saturated fats in Western diets is generally higher than that in Mediterranean diets, Ros says that even greater benefits likely would be obtained if walnuts partially replaced traditional Western dietary fats.

The typical oil found in the Mediterranean diet, olive oil, might also support health. Many studies show that MUFAs have a positive health effect, especially when substituted for SFAs in Western diets. The major dietary MUFA is oleic acid, the predominant fatty acid of olive oil. In a typical Mediterranean diet, MUFAs usually provide more than 15% of energy. Coronary heart disease and high blood pressure are typically lower than in other Western countries.

Another possible health-promoter is flax (Linum usitatissimum L.), mainly produced in the United States for its “linseed oil,” a component of paints, varnishes and ink. Recently, interest is rising in flaxseed as a health food due to the high amount of polyunsaturated fatty acids in the oil. Of the total fatty acids, flax oil contains 49.7% linolenic, 14.7%, linoleic and 24.1% oleic.

Flaxseed, with its high level of omega-3 fatty acids, particularly alpha-linolenic acid, has been shown to reduce platelet aggregation and lower blood pressure. Omega-3 fatty acids from flaxseed also may help improve insulin sensitivity, modulate lipid metabolism, and benefit mild depression and attention deficit and hyperactivity disorder.

Checking out CLA
Beneficial fatty acids can be derived from a number of sources for addition directly into food or supplements. One such fatty acid, CLA, conjugated linoleic acid, consists of one or more positional and geometric isomers of linoleic acid found naturally in dairy products and meat derived from ruminant animals. In the rumen, microorganisms hydrogenate linoleic acid forming CLA. It also can be formed in animal tissues from vaccenic acid or synthesized from vegetable oils.

One product on the market for use in supplements (not yet GRAS-approved for foods) is made with proprietary manufacturing processes that convert natural linoleic acid from sunflower and safflower oil by Pharmanutrients, Inc., Lake Bluff, IL, according to Susie Rockway, Ph.D., CNS., the company’s director of scientific and clinical affairs.

“The ingredient, called CLA One™, comes in liquid oil and powdered form.” In the oil it’s 75% CLA and the other 25% are the various fatty acids that were already present in the source oil, but aren’t the active isomers. “These are free fatty acids,” she says. “If you were to put it directly on your tongue, you’d get a very mild acid bite vs. a regular triglyceride.” While there hasn’t been much work incorporating it into food products up to this point, Rockway does cite some tests underway with dairy products: “They are looking at adding it to raw milk, homogenizing it and sterilizing it and seeing if it withstands all those processes. There’s reason to think it will — there’s been studies that show it’s more prone to oxidation than oleic acid, but not by much.”

Several different CLA isomers have been identified. The major isomers differ from linoleic acid in that their two double bonds generally show up in one of three positions on the carbon chain, with either cis or trans conformation: 9 and 11, 10 and 12 or 11 and 13. Of these, rumenic acid (cis-9, trans-11) is the most common natural form with biological activity. Current findings indicate that CLA’s effects on lipid metabolism and body composition might come from its trans-10, cis-12 isomer. “The process is optimized to limit the amount of trans,” says Rockway. “We’re looking for the cis-9, trans-11 and the trans-10, cis-12. You don’t really want the trans-trans.”

Research documents CLA’s growing number of potential health benefits. Animal studies have found that CLA has beneficial effects on several types of cancer, atherosclerosis and diabetes; immune function; energy; and weight and muscle mass. The results of human studies with CLA presented at the August 2000 national meeting of the American Chemical Society indicate that the substance may help overweight adults lose weight and fat, maintain weight loss, retain lean muscle mass and control adult-onset diabetes. “Because of the human studies, the strongest evidence is for the use of CLA in weight management, but we are going into — and have patents for — diabetes and joint health,” says Rockway.

CLA has no daily intake established, but Rockway recommends that when used as a dietary supplement for body composition, that 3 grams per day is the target consumption: “So in a beverage or bar formulation, I’d like to see levels of at least 1.5 grams per serving.”

The long-chain gang
Numerous published reports over the years support the health benefits of long-chain fatty acids, particularly DHA and EPA. Eight international food nutrition organizations recommend that adults and children consume 200 to 2,000 mg per day of DHA and EPA vs. the typical American diet, which takes in only 150 mg of DHA omega-3 per day. LC-PUFAs have been shown to play an important role in health and disease. They have important structural functions — notably in the brain and other nervous tissues — and are precursors of prostaglandins, thromboxanes and leucotrienes, hormone-like compounds known as eicosanoids.

Some surmise that DHA is the more effective of the two popular omega-3 lcPUFAs. One 1998 Agricultural Research Service study aiming to distinguish the effects of DHA from those of another omega-3 fatty acid, EPA, found that volunteers who ate foods enriched with DHA showed an increase in heart-protective HDL-cholesterol and a decrease in blood triglycerides of about 26%.

The National Institute of Child Health and Human Development of the National Institutes of Health sponsored another study, published this year in Developmental Medicine & Child Neurology. The investigators reported advantages of dietary DHA on mental development, both cognitive and motor development.

“Since DHA is an integral component in every cell in the body, the health benefits are far reaching,” notes Mary Van Elswyk, Ph.D., vice president of scientific affairs, OmegaTech, Inc., Boulder, CO. The studies where significant health benefits are noted are in the following areas: cognitive and visual development of preterm and full-term infants — brain, eye, nervous system; maintaining adult visual health; women’s health, in maintaining normal pregnancy and babies carried to term; cardiovascular function, in triglycerides reduction, HDL elevation; and reduction of sudden cardiac death.

According to Diane Hnat, marketing manager, Roche Vitamins Inc., Parsippany, NJ, the jury is still out whether DHA or EPA is more effective in lowering triglycerides, citing four EPA vs. DHA studies where there appears to be little overall difference between the two of them. In addition, she notes that EPA, but not DHA, can be converted by cyclo-oxygenase or lipoxygenase into biologically active eicosanoids that inhibit the inflammatory activity of AA-derived eicosanoids.

Roche’s research department currently is working on optimizing the isolation and purification of PUFAs from natural raw materials. Purification steps developed by the company can produce omega-3 fatty acids without a “fishy” taste that won’t affect the taste of foods. The research program also is searching for microorganisms, such as algae, fungi and bacteria, which store PUFAs, so that DHA and EPA can be derived by biotechnological methods.

OmegaTech, has developed and patented a process that produces DHA-rich algae for food and food ingredients. “The DHA content in DHA Gold oil is approximately 40% on a fatty acid methyl ester basis (FAME),” says OmegaTech’s director of application, George Stagnitti. He describes the ingredient as “relatively clean in flavor. Flavor-sensitive foods tested, such as milk, yogurt, cheese and ice cream, have excellent sensory properties and stability when fortified with DHA Gold oil.”

More possibilities
Other products and ingredients may find new favor due to the effects of their fatty acids. Another fatty acid of interest for its potential health properties is gamma-linolenic acid (GLA). Research during the past decade has indicated this fatty acid may provide beneficial effects on diabetes, arthritis and the immune system, among other health problems. Two primary sources of this oil are borage and evening primrose, which is rich in the most biologically active triacylglycerol form of GLA. Hempseed oil also contains about 2.8% of GLA along with ALA.

What about a cooking oil that is less likely than other oils to be stored in the body as fat? It may be the effect produced by DAG oil, an oil derived from soybeans or canola. Japan’s Kao Corp. developed the oil and currently sells it in that country under the brand name Healthy Econa. The Japanese company has entered into an agreement with ADM to offer the same cooking oil to the U.S. market. The product is waiting for U.S. regulatory clearances; ADM reportedly doesn’t expect to introduce the oil before late 2002.

These are only some of the new products based on the science of fatty acids. “As we learn more about structure vs. metabolism, product developers will have nutritional data that can direct them toward more nutraceutical-oriented targets if that is their mission,” says Wainwright. “Certainly, at the same time, I would expect pressure from special interest groups, consumers, health professionals and perhaps even regulatory authorities via labeling requirements, to translate new knowledge into healthy, nutritious products that taste good.”

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