Higher consumption of refined grains other than white rice associated with a greater mortality and cardiovascular disease risk

1. Higher consumption of refined grains, with the exception of white rice, was associated with a greater risk of total mortality, and mortality from cardiovascular disease related events.

2. Consumption of whole grains was not associated with greater or decreased risk of total mortality and cardiovascular disease mortality.

Evidence Rating Level: 2 (Good)

Previous research has established that greater consumption of refined carbohydrates is associated with numerous risk factors for cardiovascular disease (CVD). However, with much of this research occurring in North American and Europe, other areas of the world that consume different forms of carbohydrates primarily may impact these findings on CVD risk. For instance, cereal grains comprise 50% of caloric intake globally, but comprise 70% of intake in low and middle income countries, such as those in Africa and South Asia. There are currently mixed results on the association between refined grain consumption and mortality or CVD risk, whereas whole grains appear to be associated with lower mortality and CVD risk. In this prospective cohort study, researchers analyzed the association of refined grains, whole grains, and white rice, with outcomes such as mortality from CVD events, total mortality, and non-CVD mortality. White rice was analyzed separate from refined grains due to it being a main staple food in Asia. The study population consisted of 137,130 participants after excluding those with baseline CVD. This population was taken from the Prospective Urban and Rural Epidemiology (PURE) study, a prospective cohort study consisting of adults aged 35-70 years from 21 countries in 5 continents. There were 5 low income, 5 lower middle income, 7 upper middle income, and 4 high income countries in the PURE study. Participants received follow-up every three years, and those recruited between 2003 and 2019 were included in the study. Overall, the study found that participants consuming >350 g/day of refined grains had a significantly higher risk of mortality from CVD events, than those consuming <50 g/day (hazard ratio 1.28, 95% CI 1.15-1.42, p for trend < 0.001). For a 50 g increase in refined grain intake, the HR was 1.02 (95% CI 1.01-1.03). There were also significant differences for total mortality and non-CVD mortality. Furthermore, no associations were found between the clinical outcomes and consumption of whole grains or white rice. In conclusion, this study confirmed an association between mortality from CVD events or non-CVD causes, and higher consumption of refined grains, with the exception of white rice.

Click to read the study in BMJ

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