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The American Heart Association weighed in on how popular diets stack up against its healthy dietary pattern recommendations, giving a low ranking to several diets billed as good for the heart.

The organization issued a scientific statement scoring the top 10 dietary patterns on adherence to its if the diets were followed as intended, rather than how people often actually eat when on the diets, noted Christopher Gardner, PhD, of Stanford University in California, who chaired the committee that wrote the statement published in .

At the top of the list, with a perfect score on the 100-point scale, was the Dietary Approaches to Stop Hypertension (DASH) diet. Other diets in the top tier with scores above 85 were the Mediterranean, pescatarian, and vegetarian (including dairy, eggs, or both) diets.

Ranking at the bottom of the list were the paleolithic (paleo) and very low carbohydrate diets, such as the ketogenic (keto) and Atkins diets.

"There really isn't any way to follow [these] diets as intended and still be aligned with the American Heart Association's dietary guidance," Gardner said in a press release. "They are highly restrictive and difficult for most people to stick with long term. While there will likely be short-term benefits and substantial weight loss, it isn't sustainable. A diet that's effective at helping an individual maintain weight loss goals, from a practical perspective, needs to be sustainable."

The rankings match fairly closely with the U.S. News & World Report "Best Diets" rankings over the past several years, which have consistently put the Mediterranean and DASH diets in the top slots both overall and for heart health.

The Mediterranean diet ranked slightly below the DASH diet in the AHA statement because it doesn't explicitly address added salt and encourages moderate alcohol consumption, whereas guidelines suggest limiting alcohol intake and not starting to drink if one doesn't already.

A number of very low fat diets -- such as the Ornish, , and diets -- are touted for their heart health, even claiming to reverse heart disease. However, these were ranked below average by the AHA, with a score of 72 out of 100. They were in the same tier as very low carbohydrate diets, such as the Zone, South Beach, and low-glycemic index diets.

"The additional avoidance of nuts and liquid plant oils in very low-fat patterns is out of alignment with AHA's emphasis on including healthy fats," Gardner's group wrote. "Similarly, low-carbohydrate patterns are problematic for limiting healthy grains, legumes, and some whole fruits, which are all AHA priority features."

Vegan and low-fat diets, both comprised of more than 10% fat, were ranked in the middle, with scores of 78 out of 100. While there's potential for both diets to support optimal cardiovascular health, they also present challenges in that regard, the AHA statement noted.

"A key challenge for the vegan pattern is its restrictive nature, making it infeasible and an impediment for long-term adherence for most patients," it said. "In addition, restricted intake of foods emphasized in the 2021 AHA dietary guidance, which was intended to help adults meet their nutrient needs through foods, places adults following vegan patterns at risk for macronutrient and micronutrient deficiencies, particularly vitamin B12 deficiency."

In addition, people often cut fat in their diet by increasing intake of less healthy carbohydrates, which tend to raise triglycerides and lower high-density lipoprotein cholesterol.

"For both patterns, the proliferation of highly processed foods that are low fat or vegan but sources of refined grains, added sugars, and sodium can often lead to implementation of the pattern not as intended but rather through higher consumption of unhealthy convenience foods," Gardner and colleagues noted.

They recommended that patients choosing a vegan or low-fat diet may require referral for more in-depth nutritional counseling.

Coming in at the bottom, with scores under 55 out of 100, were "patterns of strong concern": paleo, keto, and other very low carbohydrate diets. Even if followed optimally, these diets restrict food groups considered essential to a heart-healthy diet, such as legumes and whole grains, while allowing high saturated fat intake that is strongly discouraged by the AHA.

The statement acknowledged that each of the popular diets they ranked have healthier and less healthy ways to follow them and that nutrition misinformation is rampant, leading people to follow them in a way not as intended.

"Given the poor overall diet quality among U.S. adults, it is critical for healthcare professionals to query patients or consumers about how they implement a given pattern to identify potential misunderstanding and opportunities for modifications where room for improvement exists to better align with the AHA guidance features," the statement noted.

It suggested that providing patients resources like nutrition education may help them adopt healthy patterns as intended.

The rankings didn't consider any diets aimed specifically at managing gastrointestinal conditions or diseases, allergies, or intolerances, nor did it look at those designed to be followed short term (Whole 30) or with commercial programs (like Noom and Weight Watchers).

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