Journal Name:
Int'l Journal of Food Sciences & Nutrition
Article Title:
Comparing palmolein with different predominantly monounsaturated oils: effect on plasma lipids
Date Written:
2000
Volume:
51
Number:
Page:
S73
Author(s):
Truswell, A.
Article:
Mortality in Australia from coronary heart disease (CHD) has declined by more than 50% in the last 35 years. This observation is believed to be largely attributed to reductions in dietary saturated fats, coupled with an increase in dietary polyunsaturated fats. However, there still exist a number of commonly consumed foods in which saturated fats are dominant including biscuits, chocolate, cheese, and fast foods. The later category contains foods traditionally fried in palmolein, such as potato crisps, which ultimately supply a large proportion of dietary saturated fat. Thus, the objective of this study is to compare the effects diets containing high proportions of palmolein with diets high in monounsaturated fats such as canola, olive, and high oleic sunflower oil on blood lipids.
Palmolein was compared to canola oil (CO) by using data from two series of double blind crossover experiments carried out in 1990 and 1991 (Truswell et. al). In 1990, 21 healthy adults were randomly allocated to consume a low fat diet supplemented with either potato crisps fried in palmolein or canola oil for the first three weeks, followed by the other type, canola or palmolein for the remaining two weeks (no wash out). The men consumed 3 x 50g potato crisps/day providing 53 g of fat, while the women consumed 2 x 50g potato crisps/day providing 35g fat. Fasting venous blood were taken at the start, as well as on the last three mornings of both the first and second experimental periods. A second series of experiments were carried out in 1991 that yielded similar results. Palmolein was compared to extra virgin olive oil (OO) using data from a 1995 experiment by Choudhury et al. This study was a 30 day/30 day crossover experiment that included 21 young men and women. The oils were incorporated into the subject's diets via the assistance of a dietician at a level of 17% of total energy. Three morning bloods were drawn at the end of each experimental period and subsequently analysed for blood lipid levels. Finally, palmolein was compared with high oleic sunflower oil (HOSO) using data from a 1997 study again by Choudhury et al. This study was a randomised double blind 4 week/3 week crossover trial that included both younger and older subjects (n=42). As in the first experiment, the test oils were provided as frying oil of potato crisps (150g crisps/day for men; 100g crisps/day for women). Plasma lipids were measured at the start and on the last two mornings of each experimental period.
Results demonstrated that with CO total cholesterols were lower in comparison to palmolein. This observed reduction was due in part to lower HDL-cholesterol (HDL-C) such that total cholesterol/HDL-C was lower by 2%. Comparison of OO with palmolein resulted in similar total cholesterol values between the two oils, however, the palmolein diet resulted in higher HDL-C and lower LDL-C in comparison to OO. In addition, the diet change between palmolein and OO was confirmed in plasma lipid fatty acid profiles which showed 5% higher 16:0 on palmolein and 11% higher 18:1 on olive oil. Finally, the comparison of palmolein with HOSO resulted in lower plasma total and LDL-C values in the whole group. However, HDL-C was also 5% lower such that total-C/HDL-C was only 3% lower than on palmolein.
In conclusion, when comparing the three predominantly MUFA oils with palmolein, a higher HDL-C on palmolein diets reduced the perceived health benefit of lower total-C on the CO and HOSO diets. Surprising, however, were results obtained from the comparison of palmolein with OO which showed no difference in mean total-c between the two, as well as higher HDL-C and lower LDL-C on palmolein. The author believes these observations may be due to the higher linoleic and higher phytosterol content in palmolein (which are cholesterol lowering), as well as the higher squalene content in olive oil which ultimately is cholesterol raising., , , , ,
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