High Consumption of Processed Grains Increases Risk of Mortality and CV events 

Several prospective cohort studies and their meta-analyses have reported that higher consumption of whole grain is associated with a lower risk of mortality and cardiovascular disease. However, the association of refined grains with total mortality and cardiovascular disease has not been clearly defined. Previous studies were mostly in North America and Europe, with limited information from other parts of the world. Therefore, researchers conducted a multicentric study across the globe to evaluate the association of intake of refined grains, whole grains, and white rice with total mortality, major cardiovascular disease events, blood pressure, and blood lipids.

The Prospective Urban Rural Epidemiology (PURE) study has the distinct advantage of examining diets from diverse populations in low, middle, and high-income countries in multiple regions across the world. It was a large prospective cohort study conducted in countries across the regions of North America and Europe, South America, Africa, the Middle East, South Asia, South East Asia, and China. Researchers assessed the data of 137,130 people aged 35 to 70 years across 21 countries. They used country-specific validated food frequency questionnaires to assess intakes of refined grains, whole grains, and white rice. The major-outcome evaluated was the composite of mortality or major cardiovascular events.

Key findings of the study were:

• During follow-up, the researchers found that about 9.2% of these participants had a composite outcome event.

• They noted that the highest category of intake of refined grains (≥350 g/day or about 7servings/day) was associated with a higher risk of total mortality (hazard ratio 1.27), major cardiovascular disease events (1.33), and their composite (1.28) compared with the lowest category of intake (<50 g/day).

• They also found that higher intakes of refined grains were associated with higher systolic blood pressure.

• However, they found no significant associations between intakes of whole grains or white rice and health outcomes.

The authors concluded, "Our study from 21 countries showed that higher intake of refined grains was associated with a higher risk of total mortality and major cardiovascular events. We observed no significant association between intake of whole grains or white rice and clinical outcomes."

They further added, "Intakes of a combination of cereal grains with a lower intake of refined wheat products should be encouraged while promoting a higher intake of whole grains. Reduction in quantity and improvement in the quality of carbohydrate is essential for better health outcomes."

For further information:

https://www.bmj.com/content/372/bmj.m4948