Could plant-based diets help treat cardiovascular diseases?

In a recent article published in Nutrients, researchers identified a knowledge gap about the molecular mechanisms by which plant-based diets target cardiovascular diseases (CVDs). 

Background

In the United States of America (USA), CVD is the leading cause of mortality, claiming nearly 700,000 lives each year. Over 80% of CVD-related deaths are attributable to lifestyle factors, among which diet is a key factor.

The American Heart Association (AHA) conducted multiple epidemiological studies to understand the influence of diet on CVDs. Based on the study results, AHA concluded that diets rich in animal-based and minimally processed plant foods were associated with poor and optimal cardiovascular health, respectively.

These observations explain why the incidence of CVDs is much higher in Western countries, including the USA, where the intake of animal-based foods is 140% more than the dietary recommendations, while the intake of raw plant foods is relatively low.

In one of their previous works, the researchers outlined how intake of an animal-based diet triggered several molecular mechanisms driving CVD pathogenesis. However, there is a scarcity of studies specifically exploring the benefits of plant-based diets and not the reduced consumption of animal products.

In this article, the researchers outlined some of the benefits of specific bioactive components of plant foods beneficial for cardiovascular health, even if one consumes animal products to some extent.

Plant food consumption and cardiovascular health

All dietary fiber comes from plant sources; thus, even fiber from unprocessed foods is a proxy for plant food consumption. A rigorous systematic analysis of ~135 million person-years of data from a study by Reynolds et al. suggested an inverse, dose-dependent association of fiber intake with CVD incidence and subsequent mortality.

Further, the National Health and Nutrition Examination Survey (NHANES) data revealed that ~6% of people in the USA barely meet the minimum fiber intake recommendations.

Researchers also gathered stirring in vivo data on how dietary fiber positively alters gut microbiota to prevent metabolic disorders. Specifically, they showed how maternal low-fiber intake adversely affected the gut microbial health of neonates, increasing the likelihood of obesity due to obesogenic diet intake.

Given the role of gut microbiota in CVD pathogenesis, it is highly clinically relevant to increase plant food consumption for improved gut health.

Apart from fiber, plants are a great source of several polyphenols and secondary metabolites. Each plant has a distinctive polyphenol profile; thus, a heterogeneous plant-based diet facilitates potential synergistic effects. In mice, the consumption of blackberries and raspberries improved cardiac inflammatory signaling more than the consumption of one of the berries alone.

Researchers have outlined numerous molecular pathways through which polyphenols mediate cardiovascular function. Examples include apoptotic pathways, redox, and inflammatory pathways, and the renin-angiotensin system. However, these studies assessed single polyphenols using in vitro and in vivo animal models, while each plant food has a multitude of polyphenols.

A previous study demonstrated that higher polyphenol consumption reduced cardiovascular risk by 47% in middle-aged individuals. Likewise, the PREDIMED trial showed that the highest polyphenol intake reduced all-cause mortality risk by 37%. 

Together, these observations suggested that of all plant products, polyphenols were most protective against CVDs; however, there is a need for more work in this research area.

Furthermore, the authors outlined that in the literature, only a strict plant-based diet has shown promise to clinically reverse atherosclerosis, improve myocardial perfusion, and even treat heart failure. They also identified studies showing that a diet rich in fruits and vegetables (raw) reduced low-density lipoproteins (bad cholesterol) to an extent comparable to statin treatment.

Conclusion

To conclude, the published literature on the benefits of plant-based diets has presented imposing results but deployed less precise investigative approaches.

For instance, studies exploring the effects of Mediterranean diets on health have shown that it increases plant-based food intake but is not a plant-based diet by definition. Hence, there is a need for more clinical work in this research area.