Plant-based diet, nutritional quality, and degree of processing: what impact on cardiovascular risk?
New dietary indices from the NutriNet-Santé cohort
Study conducted by Clémentine Prioux, Emmanuelle Kesse-Guyot, Bernard Srour, Léopold K. Fézeu, Julia Baudry, Sandra Wagner, Serge Hercberg, Mathilde Touvier and Benjamin Allès
In the current context, where plant-based diets are becoming increasingly popular, it is essential to better understand their real impact on cardiovascular health. The Nutritional Epidemiology Research Team (CRESS-EREN) investigated the complexity of this relationship by considering not only the balance between plant-based and animal-based foods, but also the nutritional quality of foods and their degree of processing. The results, based on an in-depth analysis of data from the French NutriNet-Santé cohort, provide new insights into the prevention of cardiovascular diseases (CVDs).
An innovative study on diet composition and quality
Although diets rich in plant-based foods are often praised for their health benefits, especially for cardiovascular health, the high consumption of ultra-processed foods (UPFs) in some of these diets may offset these benefits. Few studies have so far examined these three essential dimensions simultaneously:
- the proportion of plant vs. animal foods,
- nutritional quality, and
- the level of food processing.
To address this issue, the researchers used data from 63,835 participants in the NutriNet-Santé cohort, followed for an average of nine years. They first calculated two original dietary indices:
- hPDI (healthy Plant-Based Diet Index), representing a healthy plant-based diet,
- uPDI (unhealthy Plant-Based Diet Index), representing an unhealthy plant-based diet.
They then developed four new innovative indices, based on the previous ones but weighted by the proportion of unprocessed (UnPF) or ultra-processed (UPF) foods consumed, according to a culturally adapted version of the NOVA classification. These indices assess not only the origin and nutritional quality of foods, but also their degree of processing—a factor often overlooked in nutritional studies.
Detailed methodology
Dietary intake was assessed using 24-hour dietary records, with quantities expressed in grams per day. The NOVA classification distinguishes four groups of foods according to their degree of processing, emphasizing the consumption of ultra-processed foods (e.g., industrial ready meals, snacks, sweetened beverages) versus unprocessed or minimally processed foods (e.g., fresh fruits, vegetables, legumes, whole grains).
Multivariate Cox models were used to adjust analyses for various confounding factors (age, sex, physical activity, medical history, etc.), allowing for a precise estimation of the risk of cardiovascular diseases (both coronary and cerebrovascular diseases) according to these dietary indices.
Key findings: quality and processing as determining factors
Participants who followed a diet richer in healthy, unprocessed plant foods and lower in animal products had a 40% lower risk of developing coronary heart disease during follow-up.
Conversely, those with a similar plant-based diet but high in ultra-processed foods did not experience a comparable reduction in risk.
In fact, participants following a diet high in unhealthy, ultra-processed plant foods and low in animal foods had a 40% higher risk of developing coronary heart disease.
Conclusion: toward a new nutritional approach
This study highlights the need to move beyond a simplistic view of plant-based diets by integrating both food quality and processing level. To effectively reduce cardiovascular risk, it is not enough to favor plant-based foods — their nutritional quality and degree of processing must also be considered.
These findings open important perspectives for nutritional guidelines and public health policies, emphasizing the importance of a healthy, minimally processed plant-based diet in the prevention of cardiovascular diseases.
Clémentine Prioux, Emmanuelle Kesse-Guyot, Bernard Srour, Léopold K. Fézeu, Julia Baudry, Sandra Wagner, Serge Hercberg, Mathilde Touvier et Benjamin Allès
