The best types of diet to prevent cardiovascular disease

Although it has been clearly established for several years that the nature of the diet exerts an enormous influence on cardiovascular health, there is still a great deal of confusion about the best ways to eat to optimize this positive impact and reduce the risk of myocardial infarction and stroke. As mentioned previously, much of this confusion stems from diametrically opposed views of the role of sugars and fats in the progression of atherosclerosis and the emergence of cardiovascular disease. This controversy has led to the development of a large number of diets that more or less severely restrict the intake of one or another of these nutrients, and even, in some cases, completely exclude certain foods. The appearance of an impressive number of books, websites or articles praising (or denigrating) some of these diets means that the population is bombarded with contradictory information, which can consequently become difficult to navigate.

Simplicity on the menu
Yet, a careful examination of the results of studies that have looked at the link between diet and cardiovascular health shows that eating well is much simpler than we think. Every 5 years, an update of the latest research by a panel of USDA experts establishes the foods and diets most likely to promote health (the latest version, published in 2021, can be consulted here), and this summary is used by the American Heart Association (AHA) to establish a list of nutritional recommendations intended more specifically to improve cardiovascular health (Table 1). What is striking about these recommendations is their great simplicity: essentially, lots of plants (fruits, vegetables, legumes, nuts), a moderate intake of foods of animal origin (mainly fish, poultry and low-fat dairy products), and few processed foods containing refined flours, added sugars or salt. These recommendations therefore leave a lot of latitude to eat healthily, without having to adopt the extreme behaviours suggested by certain diets.

Table 1. AHA nutritional recommendations for optimizing cardiovascular health. Adapted from Gardner et al. (2023). Note that the table omits another AHA recommendation, namely adjusting food intake to match energy needs and avoiding being overweight, since total calorie intake is a variable that is largely independent of the type of diet adopted.

Comparison of diets
This is particularly well illustrated by a recent study that examined the degree of compliance with the basic AHA recommendations of 10 currently popular diets (Table 2). Although these diets all recommend restricting the intake of added sugars and processed foods, they sometimes differ enormously when it comes to certain foods. Depending on the degree to which they restrict or exclude certain foods, these diets can be classified into 3 main categories:

Table 2. Main characteristics of the diets analyzed in the study.

• Non-restrictive diets: The Mediterranean and DASH (Dietary Approach to Stop Hypertension) diets can be considered very non-restrictive diets, which include a wide variety of plant foods and some animal products (poultry, fish).
  
• Moderately restrictive diets: Although they exclude all red meat and poultry, vegetarian diets are more or less restrictive depending on whether they allow an intake of fish (pescatarian), dairy products (lacto), eggs (ovo) or both (ovo-lacto). Low-carb and low-fat diets can also be considered moderately restrictive, as they restrict the intake of certain foods high in one or the other of these nutrients (for example, restriction of grains for low-carb and of nuts and vegetable oils for low-fat). 
  
• Very restrictive diets: This category includes vegan diets (no animal products), very low-fat diets (<10% of calories, often combined with a vegan diet), as well as the ketogenic (very low carbohydrate) and Paleolithic diets (no foods developed after the transition from hunter-gatherers to agriculture in the Neolithic).

The degree of compliance of these diets with the various AHA recommendations was evaluated by a panel of experts to determine which of them represented the best eating habits to promote cardiovascular health. As indicated in Table 3, this analysis revealed significant differences between the diets and identified the best and worst among them.

Table 3. Degree of compliance of different diets with the nutritional recommendations of the American Heart Association. *The sources of protein considered adequate by the AHA are predominantly plant proteins (legumes, nuts), an intake of fish/shellfish (for omega-3), low-fat dairy products instead of full-fat products and lean meats versus fatty cuts. **For some people, up to 30% of meals are eaten away from home.

• “Excellent” rating (scores of 86-100): The DASH diet (and its Nordic and Baltic variants) ranks first for its perfect adherence to AHA recommendations. Initially developed against hypertension, this diet has additional positive impacts due to its content of complex carbohydrates, proteins and quality fats (mainly from vegetable sources). Mediterranean and vegetarian diets (pescatarian and ovo/lacto) also obtain excellent scores, in agreement with the many studies that have shown a positive impact of these diets on cardiovascular health.

• “Good” rating (scores of 78): The vegan and low-fat diets have several qualities, but receive a lower score than the previous ones due to the lower intake of good unsaturated fats. These more restrictive diets are also less easy to follow outside the home and often leave more room for processed products.  

• “Fair” rating (scores 64-72): The problems with vegan and low-fat diets are even more pronounced for very low-fat diets, particularly with regard to an adequate intake of quality unsaturated fats (walnuts, seeds, vegetable oils). It should be noted, however, that while these very restrictive diets seem less recommendable to the general population than the best diets mentioned earlier, several studies have shown that they can improve the health of patients with a history of cardiovascular events when combined with intensive exercise and stress management programs.

• “Failure” rating (scores 31-53): According to this analysis, paleo and keto diets lag far behind in terms of compliance with AHA recommendations. The keto diet does a particularly poor job in this respect, in particular because of the almost complete exclusion of sources of complex carbohydrates (fruits and vegetables, whole grains, legumes), which play essential roles in maintaining cardiovascular health (see our article on the subject). The high fat intake advocated by this diet is also associated with a higher energy intake (and therefore a risk of overweight), as well as a marked increase in LDL cholesterol and the risk of cardiovascular events.

Overall, these results show that the basic principles of an optimal diet for cardiovascular health are very simple: it is a question of ensuring a regular intake of plants (fruits, vegetables, legumes) and whole grains, choosing fish/shellfish and poultry as sources of animal protein, and minimizing the intake of processed foods, which often contain too much added sugar, salt and saturated fat. Adopting much more restrictive diets that severely restrict fat or sugar or completely eliminate certain classes of foods is therefore absolutely not necessary, and can even be harmful to heart health.