Associations of vegetable and fruit consumption with metabolic syndrome. A meta-analysis of observational studies

Abstract

Objective: To examine the associations of vegetable and/or fruit consumption with metabolic syndrome (MetS).

Design: Meta-analysis of observational studies.

Setting: The electronic databases of PubMed, Web of Science and EMBASE were searched up to September 2017 for observational studies concerning the associations of vegetable and/or fruit consumption with MetS. The pooled relative risk (RR) of MetS for the highest v. the lowest category of vegetable and/or fruit consumption, as well as their corresponding 95 % CI, were calculated.

Results: A total of twenty-six observational studies (twenty cross-sectional, one case-control and five cohort studies) were included in the meta-analysis. Specifically, sixteen studies were related to vegetable consumption and the overall multivariable-adjusted RR evidenced a negative association between vegetable consumption and MetS (RR=0·89, 95 % CI 0·85, 0·93; P<0·001). For fruit consumption, sixteen studies were included and the overall multivariable-adjusted RR demonstrated that fruit consumption was inversely associated with MetS (RR=0·81, 95 % CI 0·75, 0·88; P<0·001). For vegetable and fruit consumption, eight studies were included; the overall multivariable-adjusted RR showed that vegetable and fruit consumption was also negatively associated with MetS (RR=0·75, 95 % CI 0·63, 0·90; P=0·002).

Conclusions: The existing evidence suggests that vegetable and/or fruit consumption is negatively associated with MetS. More well-designed prospective cohort studies are needed to elaborate the concerned issues further.

Keywords: Fruits; Meta-analysis; Metabolic syndrome; Observational studies; Vegetables.

Fig. 1

Flowchart for the identification of studies included in the present meta-analysis on associations of vegetable and/or fruit consumption with metabolic syndrome

Fig. 2

Forest plot of the overall multivariable-adjusted relative risk (RR) of metabolic syndrome for the highest v. the lowest category of vegetable consumption. The study-specific RR and 95 % CI are represented by the black diamond and the horizontal line, respectively; the area of the grey square is proportional to the specific-study weight to the overall meta-analysis. The centre of the open diamond and the vertical dashed line represent the pooled RR and the width of the open diamond represents the pooled 95 % CI

Fig. 3

Forest plot of the overall multivariable-adjusted relative risk (RR) of metabolic syndrome for the highest v. the lowest category of fruit consumption. The study-specific RR and 95 % CI are represented by the black diamond and the horizontal line, respectively; the area of the grey square is proportional to the specific-study weight to the overall meta-analysis. The centre of the open diamond and the vertical dashed line represent the pooled RR and the width of the open diamond represents the pooled 95 % CI

Fig. 4

Forest plot of the overall multivariable-adjusted relative risk (RR) of metabolic syndrome for the highest v. the lowest category of vegetable and fruit consumption. The study-specific RR and 95 % CI are represented by the black diamond and the horizontal line, respectively; the area of the grey square is proportional to the specific-study weight to the overall meta-analysis. The centre of the open diamond and the vertical dashed line represent the pooled RR and the width of the open diamond represents the pooled 95 % CI