Giant Study Reveals The Secret to Heart Health Isn’t Low-Carb or Low-Fat

The key to heart health isn’t cutting down on pasta or potatoes, new evidence suggests; it’s not even a low-fat diet.

The research suggests the focus of healthy eating shouldn’t necessarily be on what’s being excluded from your diet (for example, reduced carbs or lowered calories).

Instead, the emphasis should be on what you’re actually putting into your body, and the quality of those ingredients.

A study that tracked nearly 200,000 men and women in the US for around 30 years found that some low-fat and low-carb diets are better for heart health than others.

What separates them?

The key was the quality of the food itself, not the quantity of carbs or fats.

The research, led by public health researchers at Harvard University, suggests that if a diet contains too many processed foods and animal proteins or fats, or if it otherwise lacks in adequate vegetables, fruits, whole grains, healthy fats, or essential macronutrients, it may not benefit cardiovascular health as much in the long run, even if it is low carb or low fat by definition.

“Our findings highlighted that it’s not simply about cutting carbs or fat, but it’s about the quality of foods people choose to construct those diets,” concluded Harvard epidemiologist Zhiyuan Wu, who led the research, published in February.

“Focusing only on nutrient compositions but not food quality may not lead to health benefits.”

Participants in the study who ate healthy, varied diets with adequate macronutrients showed higher levels of ‘good’ cholesterol in their blood, as well as lower levels of fats and inflammatory markers compared to those who ate diets lacking in those essentials.

They also had a significantly lower risk of developing coronary heart disease, the most common cause of heart attacks.

“These results suggest that healthy low-carbohydrate and low-fat diets may share common biological pathways that improve cardiovascular health,” explained Wu.

“Focusing on overall diet quality may offer flexibility for individuals to choose eating patterns that align with their preferences while still supporting heart health.”

The findings are based on the self-reported diets of participants, who were all health professionals, so they may have had higher health awareness and better access to health care than the general population.

Related: This Diet Change Cuts Over 300 Calories a Day, Without Decreasing Meal Size

That’s somewhat limiting; however, the length of follow-up in the study is impressive, amounting to more than 5.2 million person-years.

The findings join growing evidence suggesting that eating fewer processed foods and more whole grains and vegetables is generally best for a wide range of health outcomes.

Strict diets that count calories, carbs, or fats may not be necessary.

“This study helps move the conversation beyond the long-standing debate over low-carbohydrate versus low-fat diets,” said Yale University cardiologist Harlan Krumholz, editor-in-chief of the Journal of the American College of Cardiology.

“The findings show that what matters most for heart health is the quality of the foods people eat. Whether a diet is lower in carbohydrates or fat, emphasizing plant-based foods, whole grains, and healthy fats is associated with better cardiovascular outcomes.”

The study was published in the Journal of the American College of Cardiology.