Relationship between high dietary fat intake and Parkinson's disease risk: a meta-analysis

To assess whether dietary fat intake influences Parkinson's disease risk.

We systematically surveyed the Embase and PubMed databases, reviewing manuscripts published prior to October 2018. The following terms were used: ("Paralysis agitans" OR "Parkinson disease" OR "Parkinson" OR "Parkinson's" OR "Parkinson's disease") AND ("fat" OR "dietary fat" OR "dietary fat intake").

Included studies were those with both dietary fat intake and Parkinson's disease risk as exposure factors. The Newcastle-Ottawa Scale was adapted to investigate the quality of included studies. Stata V12.0 software was used for statistical analysis.

The primary outcomes included the relationship between high total energy intake, high total fat intake, and Parkinson's disease risk. The secondary outcomes included the relationship between different kinds of fatty acids and Parkinson's disease risk.

Nine articles met the inclusion criteria and were incorporated into this meta-analysis. Four studies scored 7 and the other five studies scored 9 on the Newcastle-Ottawa Scale, meaning that all studies were of high quality. Meta-analysis results showed that high total energy intake was associated with an increased risk of Parkinson's disease (P = 0.000, odds ratio (OR) = 1.49, 95% confidence interval (CI): 1.26-1.75); in contrast, high total fat intake was not associated with Parkinson's disease risk (P = 0.123, OR = 1.07, 95% CI: 0.91-1.25). Subgroup analysis revealed that polyunsaturated fatty acid intake (P = 0.010, OR = 1.03, 95% CI: 0.88-1.20) reduced the risk of Parkinson's disease, while arachidonic acid (P = 0.026, OR = 1.15, 95% CI: 0.97-1.37) and cholesterol (P = 0.002, OR = 1.09, 95% CI: 0.92-1.29) both increased the risk of Parkinson's disease. Subgroup analysis also demonstrated that, although the results were not significant, consumption of n-3 polyunsaturated fatty acids (P = 0.071, OR = 0.88, 95% CI: 0.73-1.05), α-linolenic acid (P = 0.06, OR = 0.86, 95% CI: 0.72-1.02), and the n-3 to n-6 ratio (P = 0.458, OR = 0.89, 95% CI: 0.75-1.06) were all linked with a trend toward reduced Parkinson's disease risk. Monounsaturated fatty acid (P = 0.450, OR = 1.06, 95% CI: 0.91-1.23), n-6 polyunsaturated fatty acids (P = 0.100, OR = 1.15, 95% CI: 0.96-1.36) and linoleic acid (P = 0.053, OR = 1.11, 95% CI: 0.94-1.32) intakes were associated with a non-significant trend toward higher PD risk. Saturated fatty acid (P = 0.619, OR = 1.01, 95% CI: 0.87-1.18) intake was not associated with Parkinson's disease.

Dietary fat intake affects Parkinson's disease risk, although this depends on the fatty acid subtype. Higher intake of polyunsaturated fatty acids may reduce the risk of Parkinson's disease, while higher cholesterol and arachidonic acid intakes may elevate Parkinson's disease risk. However, further studies and evidence are needed to validate any link between dietary fat intake and Parkinson's disease.