Olive oil is touted as the gold standard among all edible oils today; a reputation that has been gained primarily from its association of 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 and 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. This is despite the fact that there appears to be very little validation by direct comparison between olive and these monounsaturated oils.
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 with its large population mass. Currently, the palm olein that is available globally averages 47-53% of its composition as the same oleic acid that is found in olive oil and the other monounsaturated oils. Does 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 and make a healthy choice.
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 on the head. 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 possible 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.
Palm olein and olive oil are comparable for their effects 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.
- 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.
- The effect of palm olein and of canola oil on plasma lipids was examined in double blind experiments in healthy Australian adults. Palm oil performed better than canola oil in raising the “good” HDL cholesterol.
- A double blind crossover study showed that a palm olein-rich diet is identical to an oleic acid-rich diet.
- A study on fifty-one Pakistani adults showed that those given palm oil rich diets provided lipid profiles better than those given sunflower oil. Palm oil increased HDL-cholesterol and Apo-A1 levels. Hydrogenated cottonseed oil behaved the worst by raising blood triglycerides and lipoprotein levels.
- 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.
- Sundram et al. fed 23 healthy normocholesterolaemic male volunteers carefully designed whole food diets containing canola oil (18:1-rich), palm olein (16:0-rich) or an American Heart Association Step 1 diet (AHA), all contributing approximately 31% en fat and < 200mg dietary cholesterol/day. The AHA oil blend was obtained by blending soyabean oil (50%), palm oil (40%) and canola oil (10%) which resulted in a 1:1:1 ratio of the saturates, monounsaturated and polyunsaturated. Serum TC and LDL-C were not significantly affected by these three diets despite manipulations of the key fatty acids. The high 18:1 canola and high 16:0 palm olein resulted in almost identical plasma and lipoprotein cholesterol. Only HDL-C after the AHA diet was significantly raised compared with the other two diets. The findings of the above study have now become the subject of a patent advocating a balanced fatty acid ratio for maintaining a proper LDL/HDL-cholesterol ratio that could be cardio-protective.
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 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.