Dyslipidaemia and a hypercoagulable state are known risk factors for cardiovascular disease (CVD), while diet plays an important role in the risk prevention thereof. Dietary fats and fatty acids are known dietary factors to modulate plasma lipids and lipoproteins. Controlled dietary experiments have indicated that plasma activities of coagulation and fibrinolytic parameters may also be affected by the fatty acid composition of the diet, but few studies have been performed to establish the specific effects of individual fatty acids on the haemostatic system. Palm oil (PO), widely used in the food industry as a result of several beneficial functional characteristics, is a rich source of saturated fatty acids (SFA), specifically palmitic acid, as well as mono-unsaturated fatty acids (MUFA) and tocotrienols. Red palm olein (RPO) is the unrefined form of PO, and contains, in addition to its high content of tocotrienols, also high levels of carotenoids. Although the effects of PO on lipids and haemostatic variables have been rather well studied, inconsistent results were found. The effects of RPO on these variables, however, have only been studied to a very limited extent.
The main objectives of this study were thus to investigate, by means of sensory evaluation, the feasibility of the introduction of RPO into the diet of an urban, white South African population group and subsequently, to investigate the effects of refined, bleached and deodorized palolein (POL) and RPO on lipid levels and haemostatic profiles when compared to sunflower oil (SFO) in hyperfibrinogenaemic adults in a randomised, controlled, single blind parallel study. To attain these main objectives, the following objectives for each of the two studies were stated as:
• Firstly, to evaluate, by means of a sensory consumer panel, the acceptance of, preference for and intended consumption of muffins and rusks containing either RPO or SFO in order to determine the possibility of successful inclusion of the above mentioned products, as carriers for the experimental oils, in a successive dietary intervention study.
• Secondly, to monitor dietary changes and compliance by estimating food and nutrient intakes; to investigate the effects of the inclusion of POL and RPO in the diet on plasma fatty acids [myristic acid (C14:0), palmitic acid (C16:0),
palmitoleic acid (C16:1, n-7), oleic acid (C18:1) and linoleic acid (C18:2, n-6)]; serum lipids [total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDLC) and low-density lipoprotein cholesterol (LDLC)]; plasma haemostatic factors [fibrinogen, D-dimer, plasminogen activator inhibitor-1 activity (PAI-1act), tissue plasminogen activator antigen (tPAagt), thrombin-antithrombin complex (TAT) and plasmin-antiplasmin complex (PAP)]; as well as fibrin network characteristics (FNC) [mass-length-ratio (MLR), permeability (Ks) and compaction].
• Consumer study: In this study, the sensory acceptability of, preference for and consumption intent of muffins, baked with either RPO or SFO (control), was evaluated firstly by a general consumer group of 144 participants, followed by the evaluation of muffins and rusks baked with RPO or SFO amongst a second group of 67 consumers, who were also recruited for the subsequent intervention study. A 5-point hedonic and food action rating scale was used for evaluation by both groups. Acceptability of appearance, colour, texture and flavour was separately evaluated to determine overall acceptability.
• Dietary intervention study: Fifty-nine free-living hyperfibrinogenaemic volunteers participated in this randomized, controlled, single blind, parallel study. After a run-in period of four weeks during which the subjects received 25g/day of SFO in baked products (muffins and rusks) they were paired according to gender, age and body mass index (BMI) and randomized into three groups receiving either 25g/day of RPO or POL or SFO in baked products for another four weeks. Dietary intakes, anthropometrical measurements, serum lipids, plasma fatty acids, haemostatic profiles and FNC were measured before the run-in and after respectively 4 and 8 weeks.
• Consumer study: In the first consumer group, SFO muffins scored statistically higher for colour, texture, and overall acceptability, and consumers intended to eat it more often compared to the RPO muffins. The practical significance of these differences was, however, small. The mean score for
overall acceptability of the RPO muffins was very high (4.2 on a 5-point scale), and consumers intended to eat it often (one muffin per day). Because consumers indicated that they would only eat one RPO muffin per day, alternative methods had to be investigated for inclusion of the 25g/day of RPO in the dietary intervention study. It was decided to also provide high-fibre rusks containing the oils. Within the second consumer group high-fibre muffins baked with RPO and SFO were rated equally acceptable on all the evaluated sensory attributes and no significant difference was found in preference for, or consumption intent of muffins baked with either RPO or SFO in this group. Consumers in the second group rated RPO muffins significantly higher on several of the sensory attributes compared to the general consumer group. RPO rusks were also found very acceptable on all sensory attributes by this group, while consumers furthermore intended to eat rusks baked with RPO as often as those baked with SFO, namely one per day.
• Dietary intervention study: Compliance, as determined by collecting left over muffins and rusks, was determined as 98.8±3.2%. Energy intakes were unchanged during the study. BMI increased slightly in all three groups during the study, but the increase was not of clinical significance (median of equal or smaller than 0.2 BMI points). Mean TC and LDLC levels increased significantly with POL intake (7% and 13%, respectively), compared to intake of RPO and SFO. The increase may in part be explained by the significant increase in plasma C16:1, n-7, a metabolite of C16.0, and the significant decrease in plasma C18:2, n-6 with intake of POL but not with intake of RPO or SFO. Although the same increase in HDLC was found in all three groups, it was only significant in the RPO group, namely 7%. No significant changes with intake of POL or RPO were observed on PAI-1act, TAT, PAP, D-dimer or fibrinogen. RPO beneficially changed tPAag levels by decreasing it compared to POL and SFO intake. RPO and POL did not have independent effects on FNC. All three oils, to different degrees, beneficially affected FNC. POL increased MLR and compaction, RPO increased compaction and tended to increase Ks, and SFO increased compaction and tended to increase MLR. MLR was significantly negatively associated with plasma C16:0 and positively associated with total plasma unsaturated fatty acids.
• Consumer study: RPO products were not preferred to SFO products, but consumers of both groups evaluated the overall acceptability of RPO products as very high (≥4.0 on 5-point scale), and intended to eat it often (at least once/day). Acceptance of, and compliance with RPO products were thus considered to be optimal in the subsequent dietary intervention trial.
• Dietary intervention study: In this study the intake of 25g RPO per day by
hyperfibrinogenaemic patients did not increase TC and LDLC as seen with POL intake. A beneficial effect of increased HDLC could possibly be attributed to RPO. RPO may furthermore even have beneficial effects on risk markers of CVD by the decreasing effect it had on plasma tPAag levels. Even though POL and RPO did not influence the other haemostatic variables it, at least, did not have any negative effects. Unsaturated fatty acids may have beneficial effects on FNC, but this effect needs to be examined in other studies with the appropriate study design before more definite conclusions can be made.
RPO, a good source of vitamin A precursors and vitamin E, may thus possibly be regarded as an excellent, safe and healthy choice for use by the food industry as well as for home cooking. Further studies are, however, needed to confirm and/or verify results of the current study.||