Refined Grains May Increase the Risk for Cardiovascular Diseases and Affect the Diet-Mental Health Relationship
As technological advances revolutionized agriculture and food science, foods are now processed at industrial scales and supplied in abundance to meet global demands. However, changes in food production have led to the creation of items that are now consumed in excess, particularly products with refined grains and added sugars.
Changes in food production have led to the creation of items that are now consumed in excess, particularly products with refined grains and added sugars.
Previous studies have reported a positive association between eating refined grains and greater risk factors for cardiovascular diseases (CVD) among U.S. adults (Howard & Wylie-Rosett, 2002; Yang et al., 2014; Dehghan et al., 2017). Both refined and whole grains contribute significantly to the global daily caloric intake (Kearney, 2010).
Being that grains are pervasive in the global diet, it is critical to understand their impact on physical health and the diet-mental health relationship. Compared to whole grains, which have been associated with reduced risks of CVDs and mortality (Ye, et al., 2012), refined grains and their health outcomes have yet to be fully understood.
Being that grains are pervasive in the global diet, it is critical to understand their impact on physical health and the diet-mental health relationship.
To bridge this knowledge gap, Swaminathan et al. (2021) led a prospective cohort study (PCS) to examine the relationship between the consumption of grains and CVDs. A PCS design is longitudinal and evaluates participants that are similar but differ in one key aspect for comparison of the same outcome. Utilizing data in their analysis from 2003 to 2019 from the Prospective Urban Rural Epidemiology (PURE) study, researchers compared the diets of participants from low-, middle-, and high-income countries in an effort to observe how different intake levels of refined grains, whole grains, and white rice are associated with CVDs and mortality (Corsi et al., 2013; Swaminathan et al., 2021). This study did not compare the relationship between CVDs and no, or minimal, grain consumption (as in a ketogenic or low-carbohydrate diet).
Refined grains are defined as products modified to have low fiber content like white bread, dessert/pastries, processed noodles/pasta, and breakfast cereals.
White rice was stratified as a group separate from refined and whole grains as 60% of the participants in the PURE dataset were from Asia, where white rice is an integral part of their diet. Furthermore, refined grains are defined as products modified to have low fiber content like white bread, dessert/pastries, processed noodles/pasta, and breakfast cereals. In contrast, whole grains are foods made with intact grains like oats and whole wheat, which have higher fiber content.
The authors found that a higher dietary intake of refined grains in countries like China and in South East Asia is significantly associated with higher risks of mortality, major CVDs, and comorbidities such as high blood pressure, myocardial infarction, strokes, and heart failure (Figure 1). This relationship was not observed in regions of South Asia where white rice constitutes the highest grain intake or where whole grain is the staple, as in Africa. Particularly for diets comprised largely of white rice, there is less concern about high intake as the countries whose individuals commonly eat white rice do so at controllable levels with their meals as it is customary to pair it with other protein- or vegetable-based dishes.
Figure 1. Eating high amounts of refined grains is significantly associated with greater risks for mortality and developing cardiovascular diseases. This relationship was not found for whole-grain foods like oatmeal and wheat bread.
A higher dietary intake of refined grains in countries like China and in South East Asia is significantly associated with higher risks of mortality, major CVDs, and comorbidities such as high blood pressure, myocardial infarction, strokes, and heart failure.
In their discussion, the authors hypothesized that this outcome is a direct result of the production process of refined grains, which makes their sugar content more easily absorbed into the bloodstream. As a result, this elevates insulin levels and causes blood glucose to decrease, ultimately tricking the brain into thinking it is still hungry and promoting feeding behaviors that lead to overeating, obesity, and CVDs. While the implications of these results on cardiovascular health and the ways that diet can affect our physical (and therefore psychological) well-being demand further research, Swaminathan et al. shed light on the importance of choosing a balanced diet to maintain physical and dietary health.
Processed refined grains ultimately trick the brain into thinking it is still hungry and promote feeding behaviors that lead to overeating, obesity, and CVDs.
Find these and more studies showing how the dietary intake of sugar and processed foods affect mood, brain, and behavior in the Nutritional Psychology Research Library (NPRL). You can also sign up for the CNP Newsletter to stay informed!
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