Heart diseases are on the rise, with it still being one of the leading causes of death globally. Cardiovascular diseases account for 17.9 million deaths worldwide in 2023. Diet plays a crucial role in heart health and in reducing the risk of heart disease. A recent study examined the relationship between heart disease and diet and has identified one that benefits the heart. A large study by researchers at Harvard T.H. Chan School of Public Health found that the quality of the food matters more than cutting carbs or fat. The findings will be presented at NUTRITION 2025, the flagship annual meeting of the American Society for Nutrition, which will be held in Orlando this week. Quality over quantity
The new study found that when it comes to protecting the heart, the types of foods one eats may be more important than whether they follow a low-carbohydrate or low-fat diet. To understand what works in favour of the heart, the researchers followed almost 200,000 people for several decades, and observed that the quality of food consumed matters as much as following a low-carbohydrate or low-fat diet. The findings suggested that choosing healthy, high-quality foods is key to protecting the heart.Previously, low-carbohydrate and low-fat diets have been endorsed by health experts for their potential health benefits, such as weight management and improved blood sugar and cholesterol levels. However, the impact of these diets on reducing heart disease risk has remained an ongoing debate.“We found that what you eat on low-carb or low-fat diets matters just as much as the diet itself. Healthy versions of these diets—those rich in plant-based foods and whole grains—were linked to better heart health outcomes and improved metabolic function. In contrast, low-carb and low-fat diets emphasizing unhealthy foods were associated with a higher risk of heart disease,” said Zhiyuan Wu, PhD, a postdoctoral fellow in the lab of Qi Sun, MD, ScD, at Harvard T.H. Chan School of Public Health, said in a release. The study
To understand the link, the researchers analyzed data from three large cohorts: 43,430 men in the Health Professionals Follow-Up Study (1986–2016), 64,164 women in the Nurses’ Health Study (1986–2018), and 92,189 women in the Nurses’ Health Study II (1991–2019). The scientists followed these nearly 200,000 participants for several decades, tracking their dietary habits and whether they developed heart disease. Participants completed detailed food frequency questionnaires over time, allowing researchers to score their diets based on the quality of carbohydrates, fats, and proteins consumed.The researchers classified carbohydrates, fat,s and proteins from foods such as whole grains, fruits, vegetables, nut,s and legumes as high-quality nutrients, or healthy, while carbohydrates from potatoes and refined grains, as well as saturated fats and proteins from animal-based foods, were categorized as low-quality, or unhealthy.For more than 10,000 participants, the team also examined blood metabolites to understand how diet quality influenced metabolic health. “This approach allowed us to better understand the biological effects of these diets and strengthened our findings,” Wu said.Take away
The researchers found that the participants who followed a healthy low-carbohydrate or low-fat diet had a lower risk of developing coronary heart disease, while those on unhealthy versions saw an increased risk. These healthy diet patterns, whether a low-carbohydrate or low-fat diet, lowered the risk of developing heart disease by about 15%.
“Our findings suggest that improving food quality is crucial for improving heart health. Regardless of whether someone follows a low-carbohydrate or low-fat diet, emphasizing whole, minimally processed and plant-based foods and limiting refined grain, sugar, and animal foods, can significantly reduce the risk of coronary heart disease,” Wu added. What to do To keep heart diseases at bay, the researchers suggest incorporating more whole grains, fruits, vegetables, nuts and legumes while cutting back on processed meats, refined carbs and sugary foods. Pro tip? Check food labels and be mindful of added low-quality ingredients, such as added sugars in juices and processed snacks.
