OLIVE oil is touted as the gold standard among all edible oils today; a reputation that has been gained primarily from its association with a lower incidence of heart disease among the Mediterranean populations who have traditionally consumed olive oil as their main dietary fat.
The component of interest is the monounsaturated oleic acid content of olive oil, which on average is about 70% of its composition. Epidemiological studies have been further validated by clinical studies under controlled laboratory conditions that show a beneficial effect of monounsaturated oleic acid, especially that from olive oil.
Other monounsaturated oils such as Canola and rapeseed, although lower in their oleic acid content, have similarly piggy backed on the claim that they too are beneficial.
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Palm oil is derived from the flesh (mesocarp) of the fruit. |
An unexpected dietary oil within this group of monounsaturated oils is palm olein, the liquid fraction of palm oil, and a mainstay of the dietary oil consumed in many parts of the Asian continent. Currently, the palm olein that is available averages 47-53% of its composition the same oleic acid that is found in olive oil and the other monounsaturated oils.
Does the lower content of oleic acid compared to olive oil mean that palm olein is not a match for olive oil in terms of its nutritional quality? Consider the following facts.
What is the level of oleic acid required for optimum human nutrition?
With all the hype about monounsaturated fatty acids, you would have thought that there would be an easy and straightforward answer to this obvious question. Unfortunately, none of the world’s foremost authorities on dietary fats and nutrition are able to nail this. They have always used monounsaturated oleic acid as the filler fatty acid in many dietary recommendations and it now turns out that more does not necessarily mean better.
There is a nutritional analogy to this line of thinking: antioxidants are good for your health but in excess they flip and turn into pro-oxidants. They end up doing exactly the opposite and cause irrevocable damage to the very mechanisms and organs they were meant to protect in the first instance.
Thus there is still no word on what is the optimum level of oleic acid that you need in your diet and if this was known you could possibly titrate your daily fat intake with monounsaturated oils for optimum nutrition. This is where palm olein, which is relatively high in oleic acid, provides possible answers to an important human nutritional problem.
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Palm oil has a proven track record of stability during frying and hardly imparts any flavours of its own since it is a bland oil. |
Effect on blood cholesterol and lipoproteins
Palm olein has been shown to be effective in maintaining desirable plasma cholesterol and lipoprotein cholesterol levels. Monounsaturated oils rich in oleic acid are currently touted to be the healthiest of the edible fats in the human diet. While olive, rapeseed and Canola have in excess of 60% of their fatty acid composition as cis-oleic acid, palm olein has about 48% of this monounsaturated fatty acid.
The question of whether this level of oleic acid in palm olein is adequate to result in a lipoprotein-cholesterol profile that protects against coronary heart disease (CHD) was examined in a series of human trials. In these studies the exchange between palm olein and olive oil resulted in similar plasma and lipoprotein cholesterol values (total cholesterol, TC, low-density lipoprotein cholesterol, LDL-C and high density lipoprotein cholesterol, HDL-C).
This showed that in humans, palm olein could be exchanged for olive, Canola and rapeseed oils (high oleic) without adversely affecting serum lipids and lipoprotein levels.
Some of the studies include:
A comparative study in young Australian adults showed that the total blood cholesterol, triglycerides and LDL-cholesterol levels of those fed on palm oil (palmolein) and olive oil were lower than those fed on the usual Australian diet. They showed that young Australian adults fed on palm oil diets had the same total blood cholesterol, triglycerides and “good” HDL-cholesterol levels as those fed on olive oil.
A cross-over feeding study showed that the blood cholesterol, triglycerides, HDL cholesterol and LDL cholesterol levels of palm olein and olive oil diets were comparable.
A double blind crossover study showed that a palm olein-rich diet is identical to an oleic acid-rich diet.
A study conducted on healthy Indian subjects showed that palm olein and peanut oil have comparable effects. Neither of these oils induces hypercholesterolemia. In the same project plasma lipoprotein(a) was also measured. There was a highly significant 10% decrease in Lp(a) during consumption of the palm oil rich diet. Lp(a) is a reliable indicator of risk to cardiovascular disease and a 10% decrease is thus positive.
The above-mentioned studies focussed on the oleic acid content in the different oils tested (palm olein, canola, rapeseed and olive) for their cholesterol modulating properties. Undoubtedly, oleic acid has been proven to have cholesterol-lowering properties, which are said to be equal or better than those of the polyunsaturates.
However, the optimum amount of oleic acid required to produce beneficial lipoprotein profiles has yet to be defined. In this context, palm olein containing 47-53% oleic acid was equal in its plasma cholesterol and lipoprotein modulating effect to those of higher oleic acid containing oils including olive (70%), canola (65%) and rapeseed (60%). This augurs well for palm olein and its apparent lack of cholesterolemic effects.
Current dietary recommendations require that the polyunsaturated fatty acid content in a fat optimised healthy diet is maintained at about 7% of total energy. Did you know that olive oil has very low content of the polyunsaturated fatty acid, linoleic acid? It has only about 7% of this essential fatty acid compared to palm olein, which has 12-14%.
Without doubt, linoleic acid plays an important regulatory role in human cholesterol metabolism and if you choose olive oil as your primary dietary source, you may consume insufficient amounts of this fatty acid.
Fortunately in the Mediterranean diet, other dietary components are able to provide the linoleic acid. If you are in any other region of the world and wish to make olive the main dietary fat source, first ensure that you get a healthy level of linoleic acid. In many Asian populations, palm olein has emerged as the major edible oil consumed and supplies adequate levels of linoleic acid in combination with the large variety of foods consumed in these diverse culinary settings.
Both palm olein and olive oil, by virtue of their fatty acid composition and high content of monounsaturated oleic acid, are stable to high temperature frying. However, olive oil tends to impart a specific flavour to the food that is fried with it. While this is an acceptable sensory trait, not all food preparations welcome the distinct olive flavour.
In the frying arena, nothing actually surpasses palm olein. It has a proven track record of stability during frying and hardly imparts any flavours of its own since it is a bland oil. No wonder, food manufacturers around the world opt to use palm olein as the preferred frying fat medium for food preparations.
Red palm olein and virgin olive oil
Not many of us realise that both olive and palm are the only two commercial edible oils that are derived from the flesh (mesocarp) of the fruit. Thus it is not surprising that there are many similarities in the methods of oil extraction as well as composition.
Olive oil, when processed under specific controlled conditions, yields virgin and extra virgin olive oils. Health connoisseurs rate these oils highly, quoting not only the health benefits of the fatty acid composition of these varieties, but also their high content of natural antioxidants, including polyphenols.
It is increasingly being acknowledged that the benefits of olive oil and especially of the “virgin” varieties may be a due to the combination of all these factors.
By an innovative processing technology, “red palm olein” was born, a direct competitor to the green variations of virgin olive oil. Red palm olein takes maximum advantage of nature’s generosity: the highest source of natural carotenoids in an edible oil, high content of vitamin E, including the special vitamin E tocotrienols, coenzyme Q and a phytosterol complex. All these minor constituents, along with a fatty acid composition that is a cholesterol buster, gives virgin olive oil a run for its money.