The Effect of Palm Oil on Health Outcomes: A Protocol for Systematic Reviews and Meta-analyses of Controlled Clinical Trials

It is suggested that palm oil consumption might increase the likelihood of developing chronic diseases including cardiovascular disease. Previous studies that investigated the effect of palm oil intake on anthropometric measures, blood glucose control, inflammation, and oxidative stress markers were inconclusive. This is while previous systematic review and meta-analyses should be updated.

The present study describes a protocol for a range of systematic reviews and meta-analyses to examine the effect of palm oil intake on body weight and fat, inflammatory markers, oxidative stress, liver enzymes, blood pressure, and blood glucose control indices.

ISI web of science, EMBASE, MEDLINE, Scopus, and Google Scholar will be searched using medical subject heading (MeSH) and non-MeSH keywords. Controlled clinical trials will be selected based on predefined eligibility criteria. The intra-study risk of bias will be checked by using the Cochrane collaboration's tool. Mean difference (MD) (the difference between mean change values in the intervention group/period and control group/period) and its corresponding standard deviation will be calculated to be used as effect size. A random-effects meta-analysis will be performed to pool the results. Subgroup analysis and meta-regression will be conducted to explore the possible sources of heterogeneity. Sensitivity analysis will be conducted by removing the studies one-by-one from the overall analyses. Publication bias will be assessed by inspecting funnel plots and using asymmetry tests.

The results of systematic reviews and meta-analyses might provide helpful data about the effects of palm oil consumption on different aspects of health among adults. The evidence provided by the results of systematic reviews can be useful for dietitians, clinicians, public health policy-makers, and the public.