Scientists in industry and academia are using plant biotechnology and conventional breeding to develop a range of improved oils.
Soybean oil with SDA content offers solutions to important issues related to long-term human health. Scientists in industry and academia are using plant biotechnology and conventional breeding to develop a range of improved oils. Get the latest news in this article.
The long-chain omega-3 fatty acids, EPA (icosapentaenoic acid) and DHA (docosahexaenoic acid), are vital for the health of the human cardiovascular system. In a healthy population, these acids reduce the risk of heart attack, reduce triglycerides and apparently delay the progression of age-related vascular diseases. In those who have unfortunately already suffered a heart attack, the presence of higher tissue levels of omega-3 fatty acids dramatically reduces the risk of sudden death and improves long-term survival, possibly by suppressing potential heart rhythm disturbances.
The main direct sources of EPA and DHA fatty acids are those of marine origin, especially fatty fish, such as salmon or herring. In some regions, such as Scandinavia and Japan, the intake of oily fish is relatively high. However, consumption of omega-3 fatty acids is insufficient in most parts of the world as it is often much lower than that recommended by the World Health Organization and related organizations. Fish, shellfish and fish oil supplements can be expensive.
In any case, omega-3 fatty acid intake is generally quite low even in regions considered relatively rich. Therefore, it can be concluded that price is not the most important factor and that the availability of regional food and local eating habits play a major role in determining the intake of these fats throughout the world. Because humans have a limited ability to transform other sources of dietary fat (primarily ALA, discussed below) into EPA and DHA, increasing global intake of long-chain omega-3 fats will require that different dietary sources match local dietary habits, and that contain a relatively significant amount of long-chain omega-3 fats or their precursors.
Fish and fish oil: negative aspects
Fish and fish oil pose additional problems. From a supply point of view, fish are becoming smaller due to aggressive fishing practices. Fish farming offers at least a partial solution to the problem. However, this solution contains a pitfall.
Fish do not make their own long-chain omega-3 fats, so they must include oil in their own diet to grow and maintain high levels of these fats, which ultimately benefits the consumer. Currently, most fish oil is returned directly to fish farming, creating a high demand for fish oil and increasing production costs. Perhaps most importantly, the repetition of the cycle by which the fish oil is returned to the fish farm is what leads to the bioconcentration of pollutants and fat-soluble toxins in the fish. To break this cycle you will need a new source of omega-3 fats.
Another problem is that fish oil has a fishy taste and aroma, and due to its long-chain fats and high degree of unsaturation, it is not stable in terms of storage and exposure to heat. Therefore, fish oil is not suitable for bakery products nor does it offer an adequate shelf life for commercial products. Moreover, fishy taste is acceptable if we are actually eating fish, but no one will want to consume salad dressings or crackers that taste like herring. A solution is needed that will have to be more stable (shorter chain, less unsaturated) than EPA and DHA acids, while offering the same health benefits as long-chain omega-3 fats. All this, without the taste of fish.
Why not use flax seeds and other available sources of ALA?
One possible solution is to replace omega-3 fish oil with a shorter-chain fatty acid: ALA (alpha-linolenic acid, 18:3). ALA is naturally present in plant seed oils, especially linseed oil (linseed), available as a dietary supplement and as a fatty oil. Unfortunately, the process of transforming ALA acid into EPA acid in the human body is not very efficient. Several studies have shown that 14 grams or more of ALA acid is needed to achieve the benefit of 1 gram of EPA acid.
The first step in the transformation of ALA acid to EPA in humans also turned out to be the slowest step: the transformation of ALA acid to SDA (stearidonic acid, 18:4). The logical solution would be to skip the slowest step in the transformation process and feed people directly from SDA. Therefore, one might expect that SDA acid can be transformed into EPA more efficiently, with a shorter chain and fewer unsaturated bonds than EPA acid (20:5) or DHA (22:6).
Through recent sensory and product research, SDA acid has been shown to live up to expectations: it has no fishy taste or aroma, is much more stable than fish oil in terms of storage, performs well in sensory comparisons to conventional soybean oil, and, most importantly, requires is only 3 grams of SDA acid to replace 1 gram of EPA acid (about 4 times more effective than ALA acid). The only problem is where to get enough SDA.
The solution offered by biotechnology: Although SDA acid is a natural intermediate step between ALA and EPA acids, there is very little SDA acid in food. Fatty fish contains a small amount, and can also be found in several plant sources, such as blackcurrant seed oil or echium (buglosse, a plant that is little used in Australia). However, plant biotechnology has produced a genetically modified soybean* that produces an oil with a high SDA content (approximately ¼ of total fatty acids).
How could this be achieved?
Soybeans naturally contain a small amount of ALA acid, and the transformation of linoleic acid (18:2) into ALA acid (18:3) can be improved by adding a gene for the enzyme, “delta-15 desaturase.” , a protein whose function is to add a double bond in a certain position (carbon number 15) of fatty acids. The subsequent transformation of ALA acid to SDA, which does not occur naturally in soybeans, is accomplished by the addition of another enzyme, “delta-6 desaturase,” which adds a double bond at the 6-position of ALA acid to produce SDA acid.
How effective is the SDA enriched soybean oil solution?/When will it be available?
Extensive research is underway with soybean oils and seeds containing SDA, and it is expected that this SDA oil will be launched in the US market early next decade, and later in other countries. To put the importance of this development into perspective, consider that one hectare (approximately 0.4 acres) planted with SDA soybeans would have an impact on human levels of omega-3 fatty acids equivalent to 10,000 standard servings of salmon.
Product research and consumer testing have shown that soybean oil with SDA can be incorporated into a wide range of foods. Therefore, it is expected that these seeds could become a new, more versatile and affordable terrestrial source of omega-3 fatty acids in the near future.
From an ecological point of view, SDA soybean oil will allow us to effectively supplement our intake of omega-3, without causing additional demand for the already limited fishing resources.
Major efforts are currently underway to evaluate the possibility of using SDA soybean oil to replace fish oil in fish farming applications. In this way, the cycle of bioaccumulation of fat-soluble toxins caused by feeding fish with fish oil could be broken and the demand for this limited resource could be reduced.
It is important to remember that fats present in food provide both nutritional and functional properties. For example, solid (saturated) fats, such as lard, lard or margarine, are essential in baked goods to give them the right flavor and consistency. However, lard contains high levels of cholesterol, and vegetable oils, such as soybean or corn oil, require hydrogenation for these applications, leading to high levels of trans fat. Conventional cultivation of soybeans with a high content of stearate can reduce the use of highly saturated oils (eg palm oil), eliminate trans fats by eliminating hydrogenated oils, and avoid the use of dairy products that contain both trans fats and cholesterol.
In the same way, it is not possible to use highly unsaturated fats in high temperature applications, such as frying, because they become increasingly unstable as the chain length and degree of unsaturation increase. One possible solution is to use solid animal fats (tallow or pork), but this would result in the presence of cholesterol and high levels of fully saturated fat.
Another solution would be to use partially hydrogenated vegetable oils, but that would introduce trans fats. By producing high oleic soybean oil for frying, it is possible to offer a healthier option without compromising the taste or effectiveness of the oil. A next generation product is currently being developed, with even higher levels of oleic acid (monounsaturated), lower levels of linoleic acid (18:2) and ALA acid (18.3), to improve stability as well as resulting in an even lower saturated fat content (16:0, 18:0). The future of nutritionally enhanced plant-derived oils appears promising, both for human health and the environment.