Fruit and vegetable intake and the risk of overall cancer in Japanese: A pooled analysis of population-based cohort studies

Fruits and the Risk of Type 2 Diabetes: The Korean Genome and Epidemiology Study Cohort

BACKGROUND

To determine the association between type 2 diabetes mellitus and the consumption of various fruits.

METHODS

The Korean Genome And Epidemiology Study is an ongoing prospective longitudinal cohort study of community dwellers and participants (men and women, aged 40-69 years) recruited from the national health examinee registry of Korea. Their individual consumption habits for 12 different fruit types were recorded using food frequency questionnaires. The fruits were then divided into three groups according to their glycemic indexes and glycemic loads. Participants with extreme caloric intakes, pre-existing type 2 diabetes mellitus, chronic kidney diseases, chronic liver diseases, and ongoing cancer treatments were excluded. The incidence of type 2 diabetes in the cohort was identified through self-reporting and supplemented by glycated hemoglobin and fasting blood glucose levels.

RESULTS

A total of 2,549 cases of type 2 diabetes were documented during 283,033.8 person-years of follow-up. After adjusting for personal, lifestyle, and dietary risk factors for diabetes, the pooled hazard ratio of type 2 diabetes for every serving per week of total whole fruit consumption was 1.02 (95% confidence interval [CI], 0.99-1.06; P=0.2). With mutual adjustment of individual fruits, the pooled hazard ratios of type 2 diabetes for every serving per week were 0.94 (95% CI, 0.88-1.00; P=0.039) for bananas, and 0.90 (95% CI, 0.84-0.96; P<0.001) for grapes.

CONCLUSION

Our findings suggest associations between the consumption of certain fruits and the risk of developing type 2 diabetes. A greater consumption of grapes was significantly associated with a lower risk of type 2 diabetes in our cohort, but the total amount of fruit consumption was not associated with a reduced risk.

Inverse Association between Fruit and Vegetable Intake and All-Cause Mortality: Japan Public Health Center-Based Prospective Study

BACKGROUND

A dose-response and nonlinear association between fruit and vegetable intake and mortality has been reported in Europe and the United States, but little is known about this association in Asia.

OBJECTIVES

This study aimed to evaluate the association of fruit and vegetable intake with all-cause, cancer, cardiovascular, and respiratory disease mortality in a Japanese cohort.

METHODS

In the Japan Public Health Center-based prospective study, we included 94,658 participants (mean age: 56.4; 46.0% male) without cancer and cardiovascular disease at baseline. Information on fruit and vegetable intake was collected using a validated FFQ. The Cox proportional hazard model was used to estimate HRs and 95% CIs of each quintile of fruit and vegetable intake, separately, in relation to all-cause and cause-specific mortality using the first quintile as a reference. Nonlinear associations were evaluated using a likelihood ratio test, comparing a linear model with a restricted cubic spline model.

RESULTS

During a median of 20.9 follow-up years (IQR: 19.6-23.8 y), 23,687 all-cause deaths were documented. After adjusting for age, sex, and potential confounding factors, fruit and vegetable intake was nonlinearly and significantly associated with lower all-cause mortality, with the fourth and fifth quintiles having comparable HRs (fruit: fourth quintile HR: 0.91; 95% CI: 0.87, 0.95 and fifth quintile HR: 0.92; 95% CI: 0.88, 0.96; P-nonlinearity < 0.001; vegetable: fourth quintile HR: 0.92; 95% CI: 0.88, 0.97 and fifth quintile HR: 0.93; 95% CI: 0.89, 0.98; P-nonlinearity = 0.002). Fruit intake was significantly associated with lower cardiovascular mortality (HR in the fifth quintile: 0.91; 95% CI: 0.83, 0.99; P-nonlinearity = 0.01).

CONCLUSIONS

In the Japanese population, higher intake of fruits and vegetables was nonlinearly associated with decreased all-cause mortality. These findings may contribute to the establishment of dietary recommendations for enhancing life expectancy in Asia.

Global Vegetable Intake and Supply Compared to Recommendations: A Systematic Review

Low vegetable intake is associated with higher incidence of noncommunicable diseases. Data on global vegetable intake excluding legumes and potatoes is currently lacking. A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted to assess vegetable consumption and supply in adult populations and to compare these data to the existing recommendations (≥240 g/day according to World Health Organization). For vegetable intake data online, websites of government institutions and health authorities, European Food Safety Authority (EFSA) Comprehensive European Food Consumption Database, STEPwise approach to surveillance (STEPS) and Pubmed/Medline databases were searched from March 2018 to June 2019. Vegetable supply data was extracted from Food Balance Sheets, Food and Agriculture Organization Corporate Statistical Database (FAOSTAT), 2013. Vegetable intake was expressed as means and 95% confidence intervals. Data were summarized for each region by calculating weighted means. Vegetable intake and supply data were available for 162 and 136 countries, respectively. Weighted mean vegetable intake was 186 g/day (56-349 g/day). Weighted mean vegetable supply was 431 g/day (71-882 g/day). For 88% of the countries vegetable intake was below the recommendations. Public health campaigns are required to encourage vegetable consumption worldwide. In the 61% of the countries where vegetable supply is currently insufficient to meet the recommendations, innovative food system approaches to improve yields and decrease post-harvest losses are imperative.

Evidence-based cancer prevention recommendations for Japanese

A comprehensive evidence-based cancer prevention recommendation for Japanese was developed. We evaluated the magnitude of the associations of lifestyle factors and infection with cancer through a systematic review of the literature, meta-analysis of published data, and pooled analysis of cohort studies in Japan. Then, we judged the strength of evidence based on the consistency of the associations between exposure and cancer and biological plausibility. Important factors were extracted and summarized as an evidence-based, current cancer prevention recommendation: 'Cancer Prevention Recommendation for Japanese'. The recommendation addresses six important domains related to exposure and cancer, including smoking, alcohol drinking, diet, physical activity, body weight and infection. The next step should focus on the development of effective behavior modification programs and their implementation and dissemination.