Table 1.

The effects of oil palm phenolics (OPP) in cardiovascular health.

Study Type	Sample/Population	Intervention Dose and Route	Findings	Reference
Animal study	Male New Zealand white rabbits induced with an atherogenic diet for 100 days.	OPP (1500 mg GAE/L) in drinking fluid.	OPP treatment showed no significant difference in plasma lipid profile, while slightly higher in the high-density lipoprotein cholesterol (HDL-C) level compared to control. OPP treatment resulted in significantly lower fatty streaks development compared to the control (p < 0.05). OPP treatment indicated proliferation of smooth muscle, development of intimal fibrosis and extracellular lipid. However, lipid core or necrosis was absent. The formation of foam cell was at lesser degree.	[28]
Animal study	Male spontaneously hypertensive rats (SHR).	OPP at 1500 and 3000 GAE for 20 weeks, as a beverage (30 mL/rat/day).	The prolonged OPP supplementation at 1500 mg/L GAE did not affect blood pressure in this model.	[33]
Animal study	Sprague-Dawley rats induced hypertension with L-NAME.	OPP at 1500 mg/L and 3000 mg/L GAE) as a beverage (30 mL/rat/day) for 4 weeks prior to L-NAME induction. Treatments were continued for a further two months thereafter.	OPP treatment at 3000 mg/L GAE significantly lowered the blood pressure in the L-NAME hypertension model (p < 0.001) compared to OPP dosed at 1500 mg/L GAE (p < 0.01). OPP treatment at both doses did not return BP to a complete normalization to the baseline level of the control group. OPP treatment at 3000 mg/L GAE significantly reduced the duration of ventricular tachycardia (p < 0.01). There were no episodes of ventricular fibrillation occurred when compared to the control group.
Animal study	Male SHR.	Fractionated OPP (as a single oral dose, 250 mg/kg) was introduced via pipette positioned at the back of the tongue of SHR.	The OPP fractions reduced mean BP (7–27 mmHg) within 6 h post-administration. Both OPP fractions showed the highest BP reduction at 6 h post-administration.
Animal study	Male Wistar Kyoto rats fed with pro-arrhythmic diet.	OPP (1500 mg/L GAE) was given as beverage (30 mL/rat/day).	OPP significantly reduced the ventricular fibrillation (VF) incidences when compared to the control group (p < 0.05). OPP-treated group had a lower percentage of VF (52%) compared to the control group (90%) OPP-treated group had lower mortality (20%) compared to control rats (40%) There was no difference in ischemic-affected myocardium area (zone-at-risk) between OPP and control groups.
Ex vivo	Isolated segments (3 mm) of the thoracic aorta and mesenteric arterial bed from male normotensive Wistar Kyoto rats and SHR.	OPP was introduced at the following doses: 0.25, 0.50, and 1.00 mg/kg to pre-contracted vascular preparations in the organ bath chamber.	In a dose-dependently manner, OPP enhanced vascular relaxation in both ex vivo systems; isolated aortic rings (conductance vessels) and perfused mesenteric vascular bed (resistance vessels).	[23]
In vitro	Conjugated dienes.	OPP extracts were added to low-density lipoprotein cholesterols (LDL-C) immediately before the addition of oxidant (copper sulphate).	In a dose-dependently manner, OPP prevented the Cu-mediated LDL oxidation. OPP have delayed the duration of conjugated diene formation when compared to the control.
Animal study	Male inbred BALB/c mice.	OPP in drinking fluids ad libitum 1500 GAE mg/L.	OPP have upregulated four lipid catabolism genes (Acadl, Acads, Hadhb, Hadhsc) and downregulated five cholesterol biosynthesis genes (Hmgcs1, Lss, Sc4mol, Fdps, Nsdhl)	[32]
Animal study	Male inbred BALB/c mice.	OPP in drinking fluids ad libitum at 1500 ppm GAE mg/L.	OPP-treated group have significantly increased the total cholersterol (TC), LDL and HDL levels OPP have downregulated the genes expressed in the presentation of endogenous antigen, metabolism of fatty acids, enzymatic activities of NADH dehydrogenase (ubiquinone) and oxidoreductase. OPP have upregulated genes expressed in the heart antioxidant activity; Gpx1 and Mgst1	[27]
Human study	25 volunteers Normolipidemic, nonsmokers, and no clinical symptoms associated with CVD.	OPP was supplemented as 300 mL beverage (containing 450 mg/GAE/day).	Following the 60 days OPP supplementation, plasma TC and LDL-C levels were significantly lower compared to the control treatment, with p = 0.025 and p = 0.04, respectively. However, the OPP-supplemented group showed insignificant changes in HDL-C, triacylglycerol (TAG) and TC/HDL ratio when compared to control treatments.	[34]