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Low-linolenic soybean

Why low linolenic soybean?
As you are probably aware, as of January 2006 all food manufacturers are required to put the amount of trans fatty acids (transfat) on their nutrition labels. The FDA set this requirement based on medical research that confirmed the relationship between trans fat in the human diet and an increased risk of coronary heart disease, as well as other chronic health conditions. Trans fats are believed to pose a greater risk to heart health, than saturated fats.

Trans fatty acids are formed when hydrogen is added to any vegetable oil. This process, called hydrogenation, brings desirable features such as spreadability, texture, and increased shelf life to naturally liquid vegetable oils. However, we now know that the hydrogenation process severely compromises the nutritional value of the oil.

The increased interest in the amount of trans fat in our diet is causing a major makeover of the American food supply. Fortunately, soybean researchers are developing a variety of alternatives to hydrogenated oil to help food manufacturers, bakeries, and restaurants reduce or eliminate trans fats from their products. Low linolenic soybean are one of those alternatives.

Low linolenic soybean oil is an alternative to hydrogenation
Soybean oil is made up of five major fatty acids: palmitic, stearic, oleic, linoleic, and linolenic. Linolenic acid is the fatty acid most responsible for making soybean oil prone to rapid spoiling, prompting the use of partial hydrogenation to increase stability and shelf life.

Soybean bred to have low levels of linolenic acid produce soybean oil that is less likely to deteriorate or go rancid, and therefore does not need to be hydrogenated. That significantly reduces the amount of trans fats in the foods made with these “low-lin” soybean oils. Soybean typically produce oil with 7% linolenic acid. Iowa State University, and several other public and private soybean breeders in the U.S. have released soybean varieties with 1% linolenic acid.

Major food manufacturers and fast food restaurants such as Kelloggs, KFC, and most recently McDonalds, have announced their intention to use a low-linolenic soybean oil, or soybean/canola combination, in an effort to eliminate trans fats from a number of their food products. This indicates how large the demand for healthy soybean oil is becoming.

Expeller-pressed oils are another way to avoid hydrogenation
In addition to modifying the oil traits of soybean, another route being used to avoid hydrogenation and trans fats is alternative extraction processes. Expeller-pressed and physically refined soybean oils have the stability of partially hydrogenated oils, but do not have the trans fats and saturated fats associated with partial hydrogenation.

This is because they contain a high level of naturally occurring antioxidants that the process of expeller pressing and physical refinement leaves intact. These antioxidants protect the oil from rancidity, maintain its shelf life, and contribute other stabilizing factors that allow it to function much like partially hydrogenated oils, but without the need for partial hydrogenation.

Low-lin soybean varieties
According to the United Soybean Board’s 2006 Soybean Quality Report, about 750,000 acres of low linolenic soybean were contracted in 2006. Next year this number is expected to triple. While the growth rate of these special use soybean is tremendous, these varieties currently represent only about 1% of U.S. production.

In addition to the low-linolenic trait, breeders are now working on mid-to high-oleic acid soybean varieties. Oleic fatty acid is the same monounsaturated fatty acid found in olive oil. It is less prone to rancidity, and has a longer shelf life than linolenic acid.

Conventional soybean oil currently contains about 25% oleic fatty acid. Many breeders, including Iowa State University’s soybean breeding program, are developing cultivars that consistently produce an oil with greater than 50% oleic acid, called mid-oleic, and hope to combine the elevated oleic acid trait into their varieties with 1% linolenic acid that are grown commercially in the Midwest.

Low-linolenic soybean varieties are available commercially from Iowa State University, and several private seed companies. For the most recent performance data on varieties with modified oil traits available from ISU, view the Performance Details table at the ISU notrans website.

More on trans fats
• A National Academy of Sciences study, released in 2002, was the final step in an eight-year process to get trans fat listed on nutrition labels. The issue of whether food labels should contain trans fat levels had been before the Food and Drug Administration since 1994. The report found there is no safe level and recommends that people eat as little of it as possible. On July 9, 2003, the FDA announced that it would require the labeling of all food products for their trans-fat content beginning January 1, 2006.

• If you limit foods that contain "partially hydrogenated" vegetable oils, you will significantly reduce the amount of trans fat in your diet.

• The most common source of trans fat is the partially hydrogenated vegetable oil found in margarines, shortenings, crackers, candies, baked goods, cookies, snack foods, fried foods (especially fast foods), salad dressing,s and other processed foods. Small amounts occur naturally in some animal products such as butter, milk products, cheese, beef, and lamb.

• You should be aware that a product claiming to have 0 grams of trans fat can actually contain up to 0.5 grams per serving. This is the current FDA definition (Canada set a different standard of zero as under 0.2 grams).

• Be aware that products marked "low in cholesterol" or "low in saturated fat" might have high levels of trans fat.

• Saturated fats are naturally-occurring fats found mainly in animal foods like meat, poultry, and full-fat dairy products, as well as in tropical oils such as palm and coconut. They are mainly solid at room temperature. Some saturated fat is part of a healthy diet, however a diet high in saturated fats has been associated with higher risks of heart disease.

For more information is a clearinghouse for information about the trans fat issue and soybean oil solutions. It is coordinated by The Soyfoods Council in cooperation with the Iowa and Illinois Soybean Associations, the United Soybean Board, QUALISOY™, and soybean seed producers and oil processors.

The United Soybean Board’s Better Bean/QUALISOY™ program is a collaborative effort among members of the soybean industry to help market soybean that result in healthier oils. One function of the program is to set industry standards by determining which soybean traits, products and processes will be eligible to carry the QUALISOY name.
Read more about the USB Better Bean/QUALISOY initiative.

More information on ISU's breeding program for modified oil traits can be found at the ISU Notrans website, including performance data on the currently available low-lin soybean varieties.

From the U.S. Food and Drug Administration:
• Trans Fat Now Listed With Saturated Fat and Cholesterol on the Nutrition Facts Label
• Questions and Answers about Trans Fat Nutrition Labeling

A useful glossary about dietary fats can be found at the website


Last Update: 4/24/07

Copyright 2003-. Palle Pedersen, Iowa State University Extension.
Please contact us with questions and comments.