What the research says about these heart-healthy diets

By Charlie Williams
Published November 4, 2020

Key Takeaways

Most health advice one hears is usually geared toward enhancing cardiovascular health, and for good reason. Heart disease remains the leading cause of death worldwide, claiming more than 9 million lives in 2016 alone—that’s nearly double the number of deaths linked to stroke (second), and roughly triple the deaths caused by chronic obstructive pulmonary disease (third) and lower respiratory infections (fourth). 

One of the most ubiquitous health recommendations—eat a heart-healthy diet—is indeed key to cardiovascular health, along with regular physical activity and not smoking. But how do some of the most popular diets stack up when it comes to improving cardiovascular health?

In this article, we’ll find out what the science says about the most popular heart-healthy diets.

Setting the benchmark

Current guidelines from the American Heart Association and the recently updated 2015-2020 Dietary Guidelines for Americans paint a clear, evidence-based picture of the types of food that support heart health. Their recommendations? Eat a variety of fruits and vegetables, whole grains, fat-free or low-fat dairy products, a variety of proteins—such as skinless poultry, lean meats, seafood, eggs, nuts, and legumes—and nontropical vegetable oils. Limit processed and red meats, saturated fats and trans fats, sweets and sugar-sweetened beverages, refined grains, and sodium.

As this list suggests, it’s important to get nutrients from a variety of food sources. However, supplements can be a useful way to counter dietary shortcomings for some people—particularly those whose geographic or socioeconomic situation prevents them from easily accessing or affording a wider range of foods. But, getting heart-healthy nutrients from a variety of whole, unprocessed foods, rather than supplements, is preferred.  

The Mediterranean diet

Interest in Mediterranean eating habits began booming in the 1960s when researchers first noticed that fewer people were dying from coronary heart disease in this region than in the US and northern Europe. What made the difference? Additional research revealed that the Mediterranean diet was associated with reduced risk factors for heart disease. 

Because this region is home to diverse groups of people, there’s no single definition of the Mediterranean diet. However, staples of this diet include daily consumption of vegetables, fruits, whole grains, and healthy fats (olives, olive oil, avocado, nuts, and seeds); weekly intake of fish, poultry, beans, and eggs; moderate portions of dairy products; and limited intake of red meat. Other key lifestyle components involve staying physical and social aspects, including staying active and enjoying meals together with friends and family. 

Large studies have consistently found that the Mediterranean diet can reduce heart failure incidence and can have favorable effects on several cardiovascular risk factors, such as body mass index, waist circumference, blood lipids, blood pressure, inflammatory markers, and diabetes. 

Low-carb diets

Low-carb diets, such as the ketogenic, Atkins, and Paleo diets, are wildly popular these days. These diets emphasize what you might expect—reduced intake of carbohydrates, like those found in grains, starchy vegetables, and fruit, while emphasizing increased intake of foods high in protein and fat. The goal of these diets is to help you lose weight, but they may also prevent or improve serious health conditions such as cardiovascular disease, high blood pressure, diabetes, and metabolic syndrome.

This type of diet has the support of scientific studies, including one that followed participants who adhered to diets containing either 5%, 15%, or 25% of total energy from carbohydrates for 12 weeks. Participants who completed the study saw significant reductions in weight, waist circumference, body mass index, and anthropometric and blood markers of cardiometabolic health. However, adherence to the low-carb diet was low in the 5% carbohydrate group, suggesting such stringent cutbacks might not be realistic for most people.

Low-carb diets have the added benefit of boosting HDL cholesterol, but they can also raise LDL cholesterol, which has been linked to an increased risk of heart disease. 

In a recent meta-analysis published in PLOS ONE, the authors concluded that “the overall effect of a low-carbohydrate diet on cardiovascular risk factors tended to be favorable at less than 6 months and 6–11 months, but after 2 years of a low-carbohydrate diet, there was no significant effect on cardiovascular risk factors.” They suggested further research is needed. 

According to a report jointly published by the American Heart Association, the American College of Cardiology, and the Obesity Society, there is insufficient evidence for researchers to be able to accurately conclude that most low-carbohydrate diets provide cardiac benefits. 

Vegetarian diets

Vegetarian diets are becoming increasingly popular, and whether pursued for better health, ethics, or both, they can have powerful cardiovascular benefits. There are many variations on vegetarian diets (vegan, lacto-ovo, and more) and they all emphasize high consumption of plant products. 

The good news is that many of the foods contained in the vegetarian diet, such as fruits, vegetables, nuts, seeds, and plant-based oils and fats, are high in fiber. In one meta-analysis, researchers found that consuming high amounts of dietary fiber can significantly reduce the incidence of cardiovascular disease, perhaps due to fiber’s ability to reduce total serum and LDL cholesterol concentrations. Vegetarian foods also contain beneficial antioxidants, like vitamin C, carotenoids, and α-tocopherol, which studies have shown are associated with a reduced risk of cardiovascular disease, as well as total-cancer and all-cause mortality. 

The bad news is that avoiding most animal products means vegetarians may rely too heavily on processed foods, which can be high in calories, sugar, fat, and sodium and can increase cardiovascular risk. Still, with a little planning and awareness of individual nutritional needs, the vegetarian diet can meet most people’s nutritional requirements while improving heart health.

DASH diet

The Dietary Approaches to Stop Hypertension, or DASH diet, was designed to help prevent and treat hypertension without the use of drugs. It originated after a multicenter trial published in 1997 found that the diet, which combined fruits, vegetables, and low-fat dairy foods, reduced systolic blood pressure by 5.5 mmHg and diastolic blood pressure by 3.0 mmHg, which was superior to control diets. DASH has been shown to improve other risk factors for heart disease as well, such as insulin resistance, hyperlipidemia, and obesity.  

Similar to the Mediterranean diet, the DASH diet is practical and doesn’t require special foods or supplements. Participants are encouraged to consume whole grains, fat-free or low-fat dairy products, fruits, vegetables, poultry, fish, and nuts. The diet discourages consumption of fatty meats, full-fat dairy products, tropical oils (coconut, palm, and palm kernel oils), sweets, and sugar-sweetened beverages. The diet also recommends limiting sodium intake to below 2,300 mg per day, which is about 1 teaspoon of salt.

An umbrella systematic review and meta-analysis of the DASH diet published in Nutrients in 2019—which included eight systematic reviews in its data pool—found that the diet was associated with a 20% reduction in cardiovascular disease incidence, a 21% reduction in coronary heart disease, a 19% reduction in stroke, and an 18% reduction in diabetes, as well as clinically significant decreases in blood pressure and body weight.

Take your pick

There are plenty of effective heart-healthy diets out there to choose from, but finding the one that’s best for you can be tough. So, here’s some advice to help you get started: Note the through line between each of these diets. They all encourage the consumption of whole, natural foods and discourage processed ones.

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