Choosing high-quality, nutrient-dense foods may be more important for heart health than simply following low-carb or low-fat diets.
📷 Kseniya Ovchinnikova/Get

A new study suggests that the nutritional value of your food choices plays a more vital role in heart di

Diets low in carbohydrates or fat can sometimes lack essential nutrients that protect the heart or may include excessive amounts of harmful ones.

In contrast, a balanced eating pattern that focuses on unprocessed, whole foods is believed to offer better protection for your cardiovascular system.

A Shift in Heart Health Thinking: Beyond Macronutrient Counts

When it comes to maintaining a healthy heart, recent findings suggest that the quality of your food choices may be more crucial than simply cutting out fats or carbohydrates.

Presented at the American Society for Nutrition’s annual meeting (NUTRITION 2025), held in Orlando, Florida from May 31 to June 3, a new study advocates for prioritizing whole, minimally processed, plant-based foods over refined grains, added sugars, and heavily processed animal products.

This research reflects a growing trend in nutritional science: moving away from one-size-fits-all recommendations toward more personalized, quality-based dietary guidance for heart health.

Restricting Carbs or Fat Alone Is Not Enough

For decades, low-fat and low-carb diets have been widely promoted as strategies to reduce chronic disease risk, manage weight, and improve heart health.

However, not all versions of these diets are created equal. The type of food consumed within these frameworks can vary significantly, and that variation matters.

Scientists from the Harvard T.H. Chan School of Public Health investigated this further by analyzing data from nearly 200,000 adults over 25 years. These individuals were part of three major long-term health studies: the Health Professionals Follow-Up Study, the Nurses’ Health Study, and the Nurses’ Health Study II.

Participants regularly completed detailed food frequency questionnaires, which allowed researchers to assess the overall healthfulness of the foods in their diets — even within low-fat and low-carb plans.

The results showed that individuals who followed nutrient-rich versions of low-fat or low-carb diets — rich in whole grains, fruits, vegetables, legumes, and nuts — had about a 15% lower risk of developing coronary heart disease.

In contrast, people who consumed diets low in fat or carbs but high in ultra-processed foods such as sugary snacks, white flour products, and processed meats faced a higher risk of heart disease.

Lead author Dr. Zhiyuan Wu, a postdoctoral researcher in nutrition at Harvard, stated in a press release:

“Healthy versions of these diets — those that emphasize plant-based foods and whole grains — were associated with better cardiovascular outcomes. Meanwhile, versions of low-fat or low-carb diets that rely on unhealthy foods showed a clear link to increased heart disease risk.”

The message is clear: the source of your carbs or fats matters just as much — if not more — than the quantity.

Blood Tests Confirm Diet Quality Affects Metabolism

To deepen their investigation, researchers also looked at metabolic markers in over 10,000 participants, focusing on how diet quality influences blood metabolites — indicators of how the body processes fat and energy.

The data revealed that diets high in healthy foods significantly improved lipid profiles and metabolic function, while unhealthy versions had the opposite effect.

Animal-based low-carb diets, often rich in saturated fats and red meat, were linked to higher cardiovascular risk. On the other hand, plant-forward low-carb diets — built around vegetables, legumes, and healthy fats — showed a protective effect.

Similarly, low-fat diets high in refined carbs and sugars increased heart risk, while low-fat diets focused on whole foods had beneficial outcomes.

Why Food Quality Outweighs Macronutrient Labels

Registered dietitian Yaa Boakye, who was not involved in the study, likens food quality to a grading rubric:

“Imagine telling a student to write a report but not giving them the grading criteria. They might complete it, but without clear expectations, the results may miss the mark.”

According to Boakye, our bodies also need a “rubric” — which is food quality — to properly interpret what we eat.

“It’s not enough to simply follow a ‘low carb’ or ‘low fat’ label. We must look at fiber, added sugars, micronutrients, and the presence of anti-inflammatory or pro-inflammatory compounds.”

A carbohydrate might come from a fiber-rich lentil or a sugary white bread — both technically carbs, but vastly different in quality. Similarly, fats can come from highly processed trans fats or heart-healthy olive oil.

Boakye emphasized that focusing only on macros can lead to nutritional blind spots, such as excessive sodium, low fiber, or missing antioxidants — all of which can undermine heart health.

“You can hit your macro goals and still have a poor diet that contributes to high blood pressure, cholesterol problems, or systemic inflammation.”

For example, a low-fat diet missing omega-3s, magnesium, or potassium might be counterproductive, while a low-carb diet lacking colorful fruits and prebiotic-rich foods can harm gut health and indirectly affect the heart.

Expert Advice: How to Eat for a Healthy Heart

Ayanna Smart, a registered dietitian and creator of The Dementia Dietitian blog, stresses the importance of balanced meals built around high-quality, unprocessed ingredients. She was not part of the study but supports its conclusions.

Smart recommends using the “plate method” to structure meals:

• Half of the plate: vegetables and fruit

• One-quarter: lean proteins (e.g., fish, beans, low-fat cheese)

• One-quarter: whole grains

“This approach naturally reduces your intake of excess fats and carbohydrates by prioritizing nutrient-dense foods.”

She added that fruits and vegetables provide fiber, helping you feel full longer and reduce snacking, while also delivering key nutrients like antioxidants, vitamins, and minerals that protect blood vessels and reduce inflammation.

Whole grains supply fiber and B vitamins, which also support heart health.

“Better blood sugar control — thanks to all that fiber — helps prevent vascular damage, a key contributor to heart disease.”

Smart also recommends lean proteins and plant-based options like legumes to keep saturated fat intake low.

Additionally, nuts and seeds offer beneficial fats that help manage LDL cholesterol, or the “bad” kind.

A high-quality diet automatically reduces the amount of ultra-processed foods, which in turn lowers sodium, unhealthy fats, and empty calories.

“Cutting back on processed items helps regulate blood pressure, prevent artery hardening (atherosclerosis), and reduce the risk of excess weight gain,” Smart concluded.

Conclusion

Rather than focusing on cutting carbs or fat alone, adopting a whole-food, nutrient-dense diet appears to be a more effective strategy for protecting heart health. Choosing quality over quantity — and focusing on how and what you eat — can make a meaningful difference in reducing heart disease risk.