A major new study reveals that vegetarian does not mean healthier. Only healthy plant-based foods are tied to better heart health.
Study: Association of Plant-Based Diets with Subclinical Cardiovascular Disease in U.S. Adults, 1999-2004. Image credit: 5PH/Shutterstock.com
In a study in the American Journal of Preventive Cardiology, researchers from Johns Hopkins University recently analyzed a large-scale dataset of a nationally representative sample of U.S. adults, highlighting the potential cardiovascular health benefits of consuming healthy plant-based foods.
Background
The scientific literature has widely documented the association between healthy dietary habits and cardiovascular health. Current dietary guidelines recommend consuming plant-based foods, including vegetables, fruits, legumes, and whole grains, for a healthy heart.
A healthy diet, characterized by a higher intake of plant foods and a lower intake of animal foods, is associated with a lower risk of cardiovascular disease. However, to accurately understand the impact of different dietary patterns on cardiovascular health, it is vital to differentiate between healthy and less healthy plant foods.
The present study was designed to determine the impact of healthy and unhealthy plant-based foods on subclinical cardiovascular disease biomarkers in the general population of U.S. adults.
The study
The study analyzed 7,708 National Health and Nutrition Examination Survey participants from 1999 to 2004.
Overall, the plant-based diet index, healthy plant-based diet index, and unhealthy plant-based diet index were calculated to differentiate between healthy and less healthy plant foods. For these indices, participants’ consumption of different food groups was scored in quintiles, with positive or reverse scoring based on whether the food group was considered healthy or unhealthy.
The impact of each plant-based diet index on three cardiac biomarkers, including cardiac troponin T, cardiac troponin I, and N-terminal pro-B-type natriuretic peptide, was assessed.
Cardiac troponins are important biomarkers of cardiac muscle damage, and they are clinically used to diagnose acute myocardial infarction. Subclinical elevations of these biomarkers can be observed in more than 50% of apparently healthy individuals.
N-terminal pro-B-type natriuretic peptide, on the other hand, is a diagnostic and prognostic biomarker for heart failure. It is released by ventricular cardiac cells in response to the stretching of ventricle (heart chamber) walls. These three biomarkers can be used to monitor the odds of cardiovascular disease in individuals without a history of cardiovascular disease.
In this study population, 2% of adults had elevated cardiac troponin I, 6% had elevated cardiac troponin T, and 15% had elevated NT-proBNP.
Study findings
The study found an inverse association between higher adherence to healthy plant foods and elevated levels of cardiac troponin I in the U.S. population. Compared to those with the lowest adherence, individuals with the highest adherence to healthy plant foods exhibited 49% lower odds of having elevated cardiac troponin I levels.
The study found a positive association between higher adherence and elevated cardiac troponin I levels regarding unhealthy plant foods. Individuals with higher adherence to unhealthy plant foods exhibited a 65% higher odds of having elevated levels of cardiac troponin I compared to those with lower adherence.
Regarding other tested cardiac biomarkers (cardiac troponin T and N-terminal pro-B-type natriuretic peptide), the study could not find any significant associations with healthy or unhealthy plant food intake.
Study significance
The study reveals that higher consumption of healthy plant foods was associated with a reduced likelihood of having elevated levels of subclinical cardiac biomarkers. Conversely, higher consumption of unhealthy plant foods was associated with an increased likelihood. The study also found that these associations remained significant after controlling for sociodemographic characteristics, lifestyle behaviors, and health status. However, as with any observational study, the possibility of confounding cannot be excluded.
The Dietary Approaches to Stop Hypertension (DASH) diet is one of the most recommended diets for cardiac health. It is defined by an increased intake of fruits and vegetables and a limited intake of saturated fat, cholesterol, red meat, sweets, and sugar-sweetened beverages. Compared to a typical Western diet, the DASH diet has significantly reduced cardiac troponin I levels.
Similar to the DASH diet, other healthy diets emphasizing plant-based foods have significantly reduced cardiac troponin I levels. These observations and the current study findings are consistent with the idea that diet quality within plant-based diets is crucial for cardiac health.
The study could not find any significant association between overall plant-based food intake and cardiac biomarkers. This finding highlights the significance of distinguishing between healthy and unhealthy plant-based diets rather than focusing solely on the overall quantity of plant-based foods consumed.
The current American Heart Association dietary guidelines recommend consuming healthy plant-based foods, such as fruits and vegetables, whole grains, and plant proteins, to promote cardiovascular health.
The observed cardiac health benefits may be attributed to specific characteristics of healthy plant-based diets, including high dietary fiber levels, low saturated fats, and high levels of antioxidants, which may not be present in all plant-based diets.
The study could not find any significant impact of healthy plant-based diets on the other two biomarkers tested, cardiac troponin T and N-terminal pro-B-type natriuretic peptide. Previous studies examining the association between diet quality and cardiac troponin T level have also not found any clear association.
Existing evidence regarding N-terminal pro-B-type natriuretic peptide indicates that sodium intake is the main influencing factor that works independently of dietary composition. This may explain why the study did not find an association between plant-based diet quality and NT-proBNP.
The study considered multiple cardiac biomarkers and assessed their associations with healthy and unhealthy plant diets in a nationally representative sample of U.S. adults after controlling for several potential confounding factors, such as sociodemographic characteristics, lifestyle behaviors, and health status. These considerations have significantly improved the robustness of the study findings.
However, the study used a 24-hour dietary recall to assess participants' dietary intake, which may potentially result in misclassification and recall bias. Moreover, because of the cross-sectional design, the study cannot establish causality or determine the changes in cardiac biomarkers over time in response to plant-based diets.
Overall, the study findings support that a higher intake of healthy plant-based diets is associated with improved cardiac biomarker profiles. This suggests that healthy plant-based diets may be valuable for promoting population-level cardiovascular health.
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