of anti-clotting hormone prostacyclin and decreases the formation of thromboxane
(Chong and Ng 1991). Qureshi et al. (2011) conducted a study to determine the
extent to which tocotrienols inhibit platelet aggregation and reduce coronary thrombosis. The study determined the comparative effects of α-tocopherol and
α-tocotrienol or tocotrienol-rich fraction (TRF) on in vivo platelet thrombosis and
ex vivo platelet aggregation after intravenous injection in anaesthetized dogs by
using Folts cyclic flow model. It was observed that collagen-induced platelet aggregation in platelet-rich plasma was decreased markedly after treatment with
tocotrienol (59%; P < 0.001) and TRF (92%; P < 0.001). α-Tocopherol produced
only a 22% decrease in platelet aggregation.
6.5.4 Reduction in Blood Pressure
It has been observed that saturated fats caused an increase in blood pressure, while
consumption of mono- and poly-unsaturated fatty acids causes a decrease in blood
pressure (Hall 2009; Salonen et al. 1988). However, studies on the effect of palm oil
diets on mean arterial pressure of rats reveals that diets containing 15% (w/w) red
palm oil fed for 18 weeks did not increase the blood pressure (Edem 2002). Cheng
et al. (2017) investigated the effects of tocotrienol-rich fractions (TRF) of palm oil in
high-fat diet-treated rats. Male, post-weaning Sprague Dawley rats were provided
high-fat (60% kcal) diet for 8 weeks followed by a TRF (60 mg/kg) treatment for
another 4 weeks. Physical, metabolic and histological changes were compared to
those on control and high-fat diets, respectively. TRF reversed stolic and diastolic
hypertension, hypercholesterolaemia, hepatic steatosis, impaired antioxidant
defence and myeloperoxidase hyperactivity triggered by the high-fat diet. Palm oil
is observed to have a protective effect on the endothelium of blood vessels. Bayorh
et al. (2005) investigated the cardiovascular effects of natural vitamin-rich palm oil
using Dahl salt-sensitive hypertension model. Male rats were fed a high-salt (8%
NaCl) or low-salt (0.3% NaCl) diet with or without palm oil for 4 weeks. The study
revealed that palm oil significantly reduced the progression of salt-induced hypertension and mortality, via mechanisms involving modulation of endothelial function
and reduction in oxidative stress (Bayorh et al. 2005).
6.5.5 Palm Oil and Coronary Heart Diseases
Approximately 90% of palm oil produced is consumed by humans, and therefore,
nutritional properties of palm oil and its fractions need to be demonstrated and
understood properly. A large number of studies conducted in animals and humans
demonstrate the nutritional adequacy of palm oil and its products in dietary trials. For
several years, palm oil was considered to be a source of saturated fat, and assumption
was made that like all other saturated fats, palm oil also raises the blood cholesterol
6 Palm/Palm Kernel (Elaeis guineensis)
155
(Chong and Ng 1991). Qureshi et al. (2011) conducted a study to determine the
extent to which tocotrienols inhibit platelet aggregation and reduce coronary thrombosis. The study determined the comparative effects of α-tocopherol and
α-tocotrienol or tocotrienol-rich fraction (TRF) on in vivo platelet thrombosis and
ex vivo platelet aggregation after intravenous injection in anaesthetized dogs by
using Folts cyclic flow model. It was observed that collagen-induced platelet aggregation in platelet-rich plasma was decreased markedly after treatment with
tocotrienol (59%; P < 0.001) and TRF (92%; P < 0.001). α-Tocopherol produced
only a 22% decrease in platelet aggregation.
6.5.4 Reduction in Blood Pressure
It has been observed that saturated fats caused an increase in blood pressure, while
consumption of mono- and poly-unsaturated fatty acids causes a decrease in blood
pressure (Hall 2009; Salonen et al. 1988). However, studies on the effect of palm oil
diets on mean arterial pressure of rats reveals that diets containing 15% (w/w) red
palm oil fed for 18 weeks did not increase the blood pressure (Edem 2002). Cheng
et al. (2017) investigated the effects of tocotrienol-rich fractions (TRF) of palm oil in
high-fat diet-treated rats. Male, post-weaning Sprague Dawley rats were provided
high-fat (60% kcal) diet for 8 weeks followed by a TRF (60 mg/kg) treatment for
another 4 weeks. Physical, metabolic and histological changes were compared to
those on control and high-fat diets, respectively. TRF reversed stolic and diastolic
hypertension, hypercholesterolaemia, hepatic steatosis, impaired antioxidant
defence and myeloperoxidase hyperactivity triggered by the high-fat diet. Palm oil
is observed to have a protective effect on the endothelium of blood vessels. Bayorh
et al. (2005) investigated the cardiovascular effects of natural vitamin-rich palm oil
using Dahl salt-sensitive hypertension model. Male rats were fed a high-salt (8%
NaCl) or low-salt (0.3% NaCl) diet with or without palm oil for 4 weeks. The study
revealed that palm oil significantly reduced the progression of salt-induced hypertension and mortality, via mechanisms involving modulation of endothelial function
and reduction in oxidative stress (Bayorh et al. 2005).
6.5.5 Palm Oil and Coronary Heart Diseases
Approximately 90% of palm oil produced is consumed by humans, and therefore,
nutritional properties of palm oil and its fractions need to be demonstrated and
understood properly. A large number of studies conducted in animals and humans
demonstrate the nutritional adequacy of palm oil and its products in dietary trials. For
several years, palm oil was considered to be a source of saturated fat, and assumption
was made that like all other saturated fats, palm oil also raises the blood cholesterol
6 Palm/Palm Kernel (Elaeis guineensis)
155