When it comes to heart health, the quality of food may be more important than simply cutting carbohydrates or fats, according to a new study.
Presented at the American Society for Nutrition’s annual meeting, NUTRITION 2025, the study suggests that prioritizing whole, minimally processed, plant-based foods while limiting refined grains, added sugars, and animal products can reduce the risk of coronary heart disease.
For years, low-carbohydrate (low-carb) and low-fat diets have been recommended to improve health and reduce the risk of heart disease. However, researchers from Harvard T.H. Chan School of Public Health found that food quality is just as important—if not more so—than merely restricting carbs or fats.
The study followed nearly 200,000 individuals from three major U.S. cohort studies over 25 years, tracking their dietary habits and heart disease outcomes. The researchers concluded that low-carb and low-fat diets that emphasize high-quality foods like whole grains, fruits, vegetables, nuts, and legumes were linked to a 15% lower risk of developing coronary heart disease. In contrast, low-carb or low-fat diets high in unhealthy foods like refined grains, sugary snacks, and processed meats were associated with a higher heart disease risk.
“Healthy versions of these diets, rich in plant-based foods and whole grains, led to better heart health and improved metabolic function. On the other hand, unhealthy versions increased the risk of heart disease,” said Dr. Zhiyuan Wu, the study’s lead author.
The researchers also found that the source of macronutrients matters. For instance, “animal-based” low-carb diets, which are high in saturated fats, were linked to increased heart disease risk. In contrast, “vegetable-based” low-carb diets showed better outcomes. Similarly, unhealthy low-fat diets relying on refined carbohydrates and added sugars increased risk, while healthy low-fat diets with whole foods reduced it.
Food Quality is Key
Registered dietitian Yaa Boakye emphasized the importance of food quality over simply adhering to low-carb or low-fat diets. She likened food quality to a grading rubric for the body, noting that it’s crucial to consider factors like fiber, added sugars, sodium, and micronutrients. “Carbohydrates and fats are broad categories, but a refined carbohydrate and a fiber-rich lentil are very different,” Boakye said.
Heart-Healthy Eating Tips
To support heart health, dietitian Ayanna Smart suggests a balanced approach: fill half your plate with vegetables and fruit, one-quarter with lean proteins, and one-quarter with whole grains. This plate model naturally reduces carbohydrate and fat intake, helping control blood sugar and manage weight—both essential for heart health.
Smart also recommends including nuts for healthy fats and fiber-rich foods like vegetables, fruits, and whole grains to maintain healthy blood sugar levels and lower heart disease risk. Reducing highly processed foods can also help manage blood pressure and prevent weight gain, which contributes to cardiovascular health.
In conclusion, the study underscores that food quality, not just the quantity of carbohydrates or fats, is crucial for maintaining heart health.
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