METHODS AND STUDY DESIGN: We searched Medline, Embase, Cochrane Central Registry of Controlled Trials and CINAHL. Clinical trials were eligible if they compared palm oil-rich diets with diets rich in MUFAs or PUFAs. We pooled results of included studies using a random effects model and assessed the quality of the evidence and certainty of conclusions using the GRADE approach.
RESULTS: Intake of palm oil intake compared to oils rich in MUFA was associated with increased levels of total cholesterol (TC) [mean difference (MD)=0.27 mmol/L; 95% CI 0.08 to 0.45], LDL-C (MD=0.20 mmol/L; 95% CI 0.02 to 0.37) and HDL-C (MD=0.06 mmol/L; 95% CI 0.02 to 0.10). Similarly, for comparison with oils rich in PUFAs, palm oil showed increased in TC (MD=0.38 mmol/L; 95% CI 0.14 to 0.62), LDL-C (MD= 0.44 mmol/L; 95% CI 0.01 to 0.88) and HDL-C (MD=0.08 mmol/L; 95% CI 0.03 to 0.13). For both comparisons, there were no significant effects on triglycerides.
CONCLUSIONS: Even though palm oil increases marginally the level of serum lipids, the evidence is mostly of low to moderate quality.
MATERIALS AND METHODS: This review uses the methodological framework of Arksey and O'Malley. A total of 19 studies were selected from 9456 studies screened from the electronic databases.
RESULTS: Majority of the studies reported no association between saturated fat (SFA) and monounsaturated fat (MUFA) with CHD. Meanwhile, seven out of 12 studies reported inverse association between polyunsaturated fat (PUFA) and risk of CHD whilst 67% of the studies found that trans-fat intake was positively associated with CHD risk.
CONCLUSIONS: This review finds that all the types of dietary fat have different effects on the risk of CHD. Nevertheless, intakes of healthy fat such as MUFA and PUFA in controlled amounts are expected to reduce CHD risk. In addition, the divergence of findings found between studies might be due to the methodological inconsistencies. More robust research is needed to determine the actual dietary determinants of CHD as it will provide important information for future development of dietary intervention.