Background Information:

Carbohydrates, proteins, and fat constitute macronutrients in diet.

The Institute of Medicine in the USA recommends an Acceptable Macronutrient Distribution Range that could support healthy nutrition intake:

• carbohydrate: 45-65%
• fat: 20-35%
• protein: 10-35%

Several popular dietary patterns (diets) are outside of the Acceptable Macronutrient Distribution Range ranges. For instance, very low-fat diets are lower in fat and higher in carbohydrates; ketogenic diet is lower in carbohydrates; Mediterranean diet is higher in fat (specifically from extra-virgin olive oil).

Key Messages:

In 2021 the American Heart Association (AHA) issued evidence-based dietary guidelines to promote cardiovascular health:

• Adjust energy intake and expenditure to achieve and maintain a healthy body weight
• Eat plenty of vegetables and fruits; choose a wide variety
• Choose foods made mostly with whole grains rather than refined grains
• Choose healthy sources of protein (mostly from plants [legumes and nuts], fish and seafood, low-fat or fat-free dairy products instead of full-fat dairy products, if meat or poultry are desired, choose lean cuts and avoid processed forms)
• Use liquid plant oils (olive, safflower, corn) rather than animal fats (butter and lard) and tropical oils (coconut, palm kernel, etc.)
• Choose minimally processed foods instead of ultraprocessed foods
• Minimize intake of beverages and foods with added sugars
• Choose and prepare foods with little or no salt
• If you do not drink alcohol, do not start; if you choose to drink alcohol, limit intake
• Adhere to this guidance regardless of where food is prepared or consumed

The AHA scientific statement describes 10 dietary pattern categories (five of which are shown in Table 1) and scored them for alignment with 9 of the 10 features from the 2021 AHA Dietary Guidelines (listed above).

Diet categories	Common/popular diet names	Emphasize	Include	Limit/ avoid
DASH style	DASH, Nordic, Baltic	Vegetables, fruits, whole grains, legumes, nuts and seeds, low-fat dairy	Lean meats and poultry, fish, nontropical oils	Limit: saturated fat, sodium, fatty meats, refined grains, added sugars, alcohol
Mediterranean style	Mediterranean diet	Vegetables, fruits, whole grains, legumes, nuts and seeds, poultry, fish and seafood (fatty), extra-virgin olive oil	Red wine (moderation)	Limit: dairy, meat, sugar-sweetened beverages, commercial bakery goods, sweets, and pastries
Vegetarian style	Lacto/ovo/lacto-ovo-vegetarian	Vegetables, fruits, whole grains, legumes, nuts and seeds	Dairy (lacto/lacto-ovo only) Eggs (ovo/lacto-ovo only)	Limit: refined grains, solid fats, alcohol Avoid: meat, poultry, fish and seafood, dairy (ovo only), eggs (lacto only)
Low carbohydrate	Zone, South Beach, low glycaemic load	Vegetables, fruits (non-starchy), nuts and seeds, fish and seafood, nontropical oils		Limit: carbohydrate 30%-40% kcal, whole and refined grains, legumes, dairy, alcohol Avoid: added sugars, fatty meat
Paleolithic	Paleo	Vegetables, fruits, nuts, lean meat, fish	Eggs	Limit: sodium Avoid: added sugars, whole and refined grains, legumes, oils, dairy, alcohol

The evaluated dietary patterns are organized into 4 tiers (roughly quartiles) based on extent of alignment with the 2021 AHA Dietary Guidelines.

Tier 1: Mediterranean, DASH-Style, Pescetarian, and Ovo/Lacto-Vegetarian Diets

If implemented as intended, these align best with the 2021 AHA Dietary Guidance (scores of >85).

Tier 2: Vegan Diets and Low-Fat Diets

These mostly align with the 2021 AHA Dietary Guidance (scores 75-85). Although tier 2 patterns can support optimal cardiovascular health, special attention is needed to ensure that vegan patterns are rich in healthy plant-based protein sources, and that low-fat patterns adequately incorporate healthy sources of unsaturated fat. (Replacing unsaturated fat with refined carbohydrates and added sugars increases cardiometabolic risk.)

Tier 3: Very Low-Fat Diets and Low-Carbohydrate Diets

These dietary patterns have low to moderate alignment with AHA Dietary Guidance (scores 55-74) even if they are followed optimally. The additional avoidance of nuts and liquid plant oils in very low-fat patterns is not in alignment with AHA’s emphasis on including healthy fats. Similarly, low-carbohydrate patterns are problematic for limiting healthy grains, legumes, and some whole fruits- all AHA priority features. However, in general, a well-designed lower-carbohydrate approach may help encourage avoidance of unhealthy carbohydrate sources such as added sugars and refined grains.

Tier 4: Paleo Diets and Very Low-Carbohydrate Diets/Ketogenic Diets

These dietary patterns align poorly with AHA Dietary Guidance (scores <55) and include patterns of strong concern: Paleo and Very Low-Carbohydrate Diets (VLCD). Even when followed optimally, they promote restriction of food groups that are considered essential features of a heart-healthy diet (legumes, whole grains) and allow high-saturated-fat sources that are strongly discouraged (from meats for both Paleo and VLCD and dairy for VLCD).

Note: The AHA Scientific Statement does not discuss dietary patterns in Asia, Latin America, and Africa as the research on these patterns is not sufficient to make recommendations. However, the 2021 AHA Dietary Guidance may be applied to several contexts by adhering to the basic principles mentioned therein.

Useful Links:

Link to the AHA Scientific Statement (Abstract):

https://www.ahajournals.org/doi/abs/10.1161/CIR.0000000000001146

Link to the Full text of the AHA Scientific Statement:

https://www.ahajournals.org/doi/epdf/10.1161/CIR.0000000000001146