Higher whole grain consumption associated with lower mortality risk

Zong G, Gao A, Hu FB, et al.
Circulation. 2016;133:2370-2380

Background

Dietary guidelines endorse the consumption of whole grains (WGs) because they contain fiber, vitamins, minerals, phytochemicals, and other healthy nutrients. However, the actual intake of WG is far below the recommended quantities (48 g/d WG ingredients) [1-4].

Data from prospective cohort studies show that the consumption of WG is associated with decreased risk of diabetes, cardiovascular diseases (CVD) and cancer, however, there are no robust findings regarding mortality risk [5-8].

In this meta-analysis, the association between WG intake and risks of total, CVD, and cancer mortality was evaluated in 786,076 participants of 14 studies (most US, 3 Scandinavian and 1 UK). Median follow-up ranged from 6-28 years (1971-2010).

Main results

• Pooled relative risk (RR) was for total mortality: 0.84 (95% CI: 0.80–0.88; P<0.001; I²=74%, P heterogeneity <0.001), for CVD mortality: 0.82 (95% CI: 0.79–0.85; P<0.001; I²=0.0%, P heterogeneity = 0.53), and for cancer mortality: 0.88 (95% CI: 0.83–0.94; P<0.001; I²=54%, P heterogeneity = 0.02).
• Dose-response analysis (no WG consumption as a reference) showed total mortality RRsat 10 g/d: 0.93 (95% CI: 0.89–0.97), at 30 g/d: 0.84 (95% CI: 0.77–0.91), at 50 g/d: 0.80 (95% CI: 0.75–0.85) and at 70 g/d: 0.78 (95% CI: 0.74–0.82). All P<0.001, P trend <0.001 and P nonlinearity =0.06.
• Dose-response analysis (no WG consumption as a reference) showed CVD mortality RRs at 10 g/d: 0.92 (95% CI: 0.88–0.96), at 30 g/d: 0.81 (95% CI: 0.75–0.89), at 50 g/d: 0.78 (95% CI: 0.72–0.84), at 70 g/d: 0.77 (95% CI: 0.68–0.87). All P<0.001, P trend <0.001 and P nonlinearity =0.10).
• Dose-response analysis (no WG consumption as a reference) showed cancer mortality RR’s at 10 g/d: 0.96 (95% CI: 0.91–1.01; P=0.12), at 30 g/d: 0.89 (95% CI: 0.89–0.99; P=0.04), at 50 g/d: 0.85 (95% CI: 0.76–0.94; P=0.001), at 70 g/d: 0.80 (95% CI: 0.72–0.89; P<0.001). P trend <0.001, P nonlinearity =0.67.
• RR for each 16-g/d increase in WG ingredient consumption (≈1 serving per day) was for total mortality 0.93 (95% CI: 0.92–0.94), for CVD mortality 0.91 (95% CI: 0.90–0.93) and for cancer mortality 0.95 (95% CI: 0.94–0.96).

Conclusion

In a meta-analysis of 14 cohort studies, the consumption of whole grain products was inversely and significantly associated with mortality in a dose-response manner, especially with CVD mortality. These results support current dietary guidelines that recommend increasing WG intake to replace refined grains.

Find this article online at Circulation

References

1. Slavin J. Why whole grains are protective: biological mechanisms. Proc Nutr Soc. 2003;62:129–134.
2. Fardet A. New hypotheses for the health-protective mechanisms of wholegrain cereals: what is beyond fibre? Nutr Res Rev. 2010;23:65–134.
3. Ferruzzi MG, Jonnalagadda SS, Liu S, et al. Developing a standard definition of whole-grain foods for dietary recommendations: summary report of a multidisciplinary expert roundtable discussion. Adv Nutr. 2014;5:164–176.
4. McGill CR, Fulgoni VL 3rd, Devareddy L. Ten-year trends in fiber and whole grain intakes and food sources for the United States population: National Health and Nutrition Examination Survey 2001-2010. Nutrients. 2015;7:1119–1130.
5. Ye EQ, Chacko SA, Chou EL, et al. Greater whole-grain intake is associated with lower risk of type 2 diabetes, cardiovascular disease, and weight gain. J Nutr. 2012;142:1304–1313.
6. Mellen PB, Walsh TF, Herrington DM. Whole grain intake and cardiovascular disease: a meta-analysis. Nutr Metab Cardiovasc Dis. 2008;18:283–290.
7. Jacobs DR Jr, Marquart L, Slavin J, et al. Whole-grain intake and cancer: an expanded review and meta-analysis. Nutr Cancer. 1998;30:85–96.
8. Huang T, Xu M, Lee A, et al. Consumption of whole grains and cereal fiber and total and cause-specific mortality: prospective analysis of 367,442 individuals. BMC Med. 2015;13:59