A New Current for Tropical Oils

May 1, 2005

8 Min Read
A New Current for Tropical Oils

May 2005

A New Current for Tropical Oils

By Sharon Palmer, R.D.Contributing Editor

Tropical oils were ousted from the U.S. fat pool 20 to 30 years ago, with much discussion of their saturated-fat status and health disadvantages. The food industry responded by jumping onto the partially hydrogenated fat bandwagon as an alternate fat source in food processing. This has come to a screeching halt in the past couple of years when trans fats became known as the latest "bad" fat. Now, with the food industry on the lookout for alternatives to replace trans fats, researchers have been taking a second look at tropical oils.

The tropical pool The term "tropical oil" refers to coconut, palm kernel and palm oils. Like all fats and oils, tropical oils contain various profiles of fatty acids. Coconut oil contains 92% saturated fat, palm kernel oil contains 82% saturated fat and palm oil contains 50% saturated fat.

The copra of the coconut palm yields coconut oil. It has the consistency of shortening and is also known as coconut butter. This white to slightly yellowish oil comes from East Africa, Malaysia, the Philippines, Indonesia, Sri Lanka and Australia. Coconut oil contains 50% lauric acid.

Processors extract reddish-orange palm oil from the pulp of the fruit of the African palm, which originated in Western Guinea and is cultivated in other tropical countries. African palm fruit contains between 30% and 70% nondrying oil, which is a type of oil high in saturation that doesn't dry or form a film after long exposure to oxygen. The seed kernels also contain oil. Palm oil has a high solid-glyceride content, which gives a stiffer consistency without hydrogenation. Palm oil contains 44% palmitic acid.

Surfing the science of tropicals Since tropical fats possess high levels saturated fatty acids, for years most health organizations tossed them into the saturated-fats category along with dairy and other animal fats, advising the public to limit their intake. The Dallas-based American Heart Association recommends that people should limit foods high in saturated fats, such as tropical oils, to 10% or below of total calories per day. The newly revised 2005 Dietary Guidelines for Americans echoes this recommendation.

Scientists have long established that individual fatty acids have different effects on risk factors for cardiovascular disease. Due to a broad body of research performed in the 1950s, '60s and '70s, scientists knew that saturated fats raise blood cholesterol levels, and a high level of cholesterol in the blood is a major risk of coronary heart disease, which leads to heart attack and increases the risk of stroke.

But a few recent studies have been trickling in that single tropical oils out of the saturated-fat milieu. According to a 2003 review in the Asia Pacific Journal of Clinical Nutrition written by scientists of the Asia Pacific Health & Nutrition Centre, Monash University, Melbourne, Australia, palm oil contains components with nutritional and beneficial health properties. These phytonutrients include carotenoids, vitamin E, sterols, phospholipids, glycolipids and squalene. In addition, processors can recover powerful, water-soluble antioxidants, like phenolic acids and flavonoids, from palm oil mill effluent. The researchers' bottom line was that palm fruit might offer some protection against cardiovascular disease, cancers, cataracts, macular degeneration, cognitive impairment and Alzheimer's disease.

Although palm oil contains 50% saturated fatty acids, it does not promote atherosclerosis and arterial thrombosis according to a fall 2002 review in Plant Foods for Human Nutrition. Even though palm-oil-based diets induce a higher blood cholesterol level than do corn, soybean, safflower seed and sunflower oils, the consumption of palm oil causes the endogenous cholesterol level to drop. The review credits this phenomenon to palm oil's tocotrienols and the isomeric position of its fatty acids and lists benefits, including reduced risk of arterial thrombosis and atherosclerosis, inhibition of endogenous cholesterol biosynthesis, platelet aggregation, and reduction in blood pressure.

Another study, out of the Department of Biochemistry, University of Kerala, India, was published in the Sept. 2004 issue of Clinical Biochemistry. This rat study concluded that virgin coconut oil might provide a potential benefit in lowering lipid levels in serum and tissues, as well as LDL ("bad") cholesterol oxidation by physiological oxidants -- possibly because of the polyphenol components present in the coconut oil.

Peter Jones, Ph.D., director of the Mary Emily Clinical Nutrition Research Center, McGill University, Montreal, completed two studies in 2003 on a blend of tropical oils for cooking that reduced cholesterol levels by over 13% and allowed male study participants to lose an average of 1 lb. per month. The oil (presently called "Functional Oil") contains 71% tropical oil, 12% olive oil, 7% canola oil, 7% flax seed oil and 3% phytosterols. The emphasis was on its composition of medium-chain triglycerides (MCTs). Trials were conducted over two periods of 27 days on men and women who were about 25 lbs. overweight.

Reanalyzing the tides "Tropical oils fall into both sides of the fence," says Jones. "They are vegetable oils, but some of these oils are high in palmitic acid and lauric acid, a cluster of fats that are not good for you. Certain tropical oils including coconut oils do, however, contain phytonutrients and MCT fats." He also reports that MCT fats are attracting many lipid researchers' interest, as the body processes them differently than long-chain triglycerides. His study, "Consumption of a Functional Oil Rich in Phytosterols and Medium-Chain Triglyceride Oil Improves Plasma Lipid Profiles in Men," was published in the June 2003 issue of the Journal of Nutrition.

"We got so carried away with polyunsaturated fatty acids that we promoted them to the exclusion of palm oil," says Charles Elson, Ph.D., professor emeritus, Department of Nutritional Sciences, University of Wisconsin, Madison. He studied tropical oils in the early '90s and concluded that dietary palm oil does not raise plasma cholesterol and that constituents of palm oil might play a role in health maintenance.

To sort out tropical oil's place in health, reviewing the broad body of research on fatty acids might be a good place to start. Researchers looked at the effects of dietary fatty acids on the ratio of serum total to HDL ("good") cholesterol, by performing a meta-analysis of 60 controlled trials published between 1970 and 1998. The results, published in American Journal of Clinical Nutrition in May 2003, concluded that trans fatty acids from partially hydrogenated oils are associated with the rise of coronary artery disease and that palm oil is an acceptable alternative for the food industry. In terms of the effect on the ratio of total to HDL cholesterol, palm oil is still better than the partially hydrogenated vegetable oils (trans fats) typically used in the foodservice industry, but nonhydrogenated vegetable oil provides a better lipid profile than palm oil or hydrogenated oils.

The study points out that lauric acid, a major component of tropical oils such as coconut and palm kernel oil, had the largest cholesterol-raising effect of all fatty acids, but much of this is due to a rise in HDL cholesterol. Lauric acid had a more-favorable effect on the ratio of total to HDL cholesterol than any other fatty acid, either saturated or unsaturated.

Cresting on a trans-free waveEven though tropical oils have been seen in food processing for decades, their use as food ingredients has shifted with public-opinion tides. "The triglyceride structure of palm oil differs from the structure of lard, but they both give good food formulation," says Elson. "Palm kernel oil has shorter-chain fatty acids and has a place in the market for chocolates and frostings."

"Fueled by U.S. food companies looking for trans-fat-free ingredients, we are certainly seeing heightened interest in palm oil amongst the companies, reflected by increased sampling and testing activities, increased queries at our offices, and invitations to speak about palm oil to company management teams," says T. "Tiger" Thiagarajan, regional manager, Malaysian Palm Oil Board, Selangor. "Imports of palm oil products into the United States have increased to 350,000 metric tons in 2004 from 260,000 in 2003. In fact, imports have almost tripled in the past six years."

This current momentum represents an obvious reversal of fortune for tropical oils. "There was a point when tropical fats were replaced with partially hydrogenated vegetable oils," says Barbara Retzlaff, M.P.H., R.D., research dietitian, Northwest Lipid Research Clinic, Seattle. "It was a big hit for the poor, palm-producing countries and a boon to the U.S. soy industry. Given what we know about trans fats now, perhaps we should have just stayed with the tropical fats, and I think we are likely to see a trend that direction with the new labeling laws. But I don't think we should kid ourselves that tropical fats don't raise cholesterol."

With the trans-fat-free movement cresting, alternative fat sources, such as tropical oils, are set to ride the wave for all its worth. Last season's bad boys are quite possibly the solution to this season's trans-fat challenge.

Sharon Palmer is a registered dietitian with 16 years of experience in health-care and foodservice management. She writes on food and nutrition for newspapers, magazines, websites and books. Palmer makes her home in Southern California.

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