Grain products are a major source of caloric intake worldwide, so researchers have been examining the association between the types of grains consumed and health effects. Their study shows that refined grains are associated with a higher risk of heart disease, confirming the importance of choosing whole grains.
Diet can positively or negatively influence the development and progression of chronic diseases. This is particularly the case with cereals (bread, dough, rye, barley, spelt, rice...), whether they are wholemeal or refined (white bread). A cereal is said to be complete when its envelope (bran) rich in fibre and the germ containing the nutrients and the body of the seed have been preserved. It is refined when the bran and the germ are removed to keep only the body: low in fiber, minerals and vitamins. The former are therefore more interesting from a nutritional and therefore health point of view, and a new study has just confirmed this.
The study published by the British Medical Journal points out that cereals, such as oats, rice, barley and wheat, account for about 50% of daily calorie intake worldwide and up to 70% in low- and middle-income countries, particularly in Africa and South Asia. "Whole grains tend to be richer in dietary fibre, vitamins, minerals and essential fatty acids than refined grains. Previous studies have shown that higher intakes are associated with a lower risk of cardiovascular disease and death, but no clear association has been found for refined grains," explain the researchers.
Stroke, heart attack... what impact on cardiovascular health?
To address this lack of evidence, researchers set out to evaluate the association between intakes of refined cereals, whole grains and white rice with cardiovascular disease and mortality in general. Their results are based on data from 137,130 people aged 35-70 years from 21 low-, middle-, and high-income countries who had no history of heart disease and who participated in a research project on urban and rural epidemiology (called PURE). They were particularly interested in white rice compared to other refined cereals, as more than 60% of the members of this cohort live in Asia, where rice is one of the staple foods.
Detailed information on the education, economic status, lifestyle and medical history of participants was collected at the beginning of the study, and dietary questionnaires were used to assess intakes of refined grains, whole grains and white rice. Deaths due to cardiovascular causes or serious cardiovascular events, including heart attack, stroke and heart failure, were then tracked over an average of 9.4 years. The researchers found that people in the highest category of refined cereal consumption consumed at least 350 g of refined cereals per day.
The importance of eating whole grains
After taking into account other potentially influential factors, they found that this highest category of refined cereal consumption was associated with a 27% higher risk of death and a 33% higher risk of serious cardiovascular events compared to the lowest category of consumers (less than 50 g per day). Higher intakes of refined grains were also associated with higher blood pressure, a measure of the pressure or force that blood exerts against the walls of your blood vessels called arteries. This is the most important risk factor for stroke and one of the major risk factors for heart disease.
Since this study is observational in nature, the researchers do not establish a direct link. But with data from 21 countries on five continents, they believe that they "were able to analyze broad dietary patterns, which means that the results are likely to be robust and broadly applicable to populations around the world. "As such, they suggest that at the global level, a lower consumption of refined grains should be encouraged while promoting a higher consumption of whole grains. "Reducing the quantity and improving the quality of carbohydrates is essential for better health outcomes," they conclude.
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