Diet, cardiovascular disease, and mortality: Findings from a prospective cohort study of 80 countries

A healthy diet is a key modifiable risk factor in the prevention and management of many noncommunicable diseases, disability, and mortality. The relationship between health outcomes and diet is often assessed using dietary pattern scores, such as the Mediterranean, Dietary Approaches to Stop Hypertension (DASH), Healthy Eating Index (HEI)-2010 and -2015 scores, and recently the EAT-Lancet Planetary Health Diet Index score. These dietary scores generally emphasize fruits, vegetables, legumes, nuts, and fish with varying assessments of red meat, dairy, and certain types of fat. However, many scores do not reflect recent scientific evidence, notably regarding whole-fat dairy which has demonstrated neutral or beneficial impacts on cardiometabolic profiles. 

To this effect, a study sought to develop a diet quality score using data from the Prospective Urban Rural Epidemiology (PURE) study, a large-scale epidemiological cohort that includes 166,762 individuals aged 35-70 years from the general population of 21 low-, middle-, and high-income countries across 5 continents. This healthy diet score was then applied to five existing prospective study cohorts, on a total of 245,000 individuals from 80 countries. 

The 6-point healthy diet score was derived from six food categories that have each been linked to a lower risk of mortality: fruit, vegetables, legumes, nuts, fish, and dairy. Outcomes of interest included major cardiovascular disease (CVD), myocardial infarction (MI), stroke, heart failure, and mortality. Analyses adjusted for potential confounders, such as lifestyle factors and comorbidities.

Based on the mean intake of foods by level of diet score, the “most healthy” diet (score ≥5 points) contained 5 servings of fruits and vegetables, 0.5 servings of legumes, 1.2 servings of nuts, 0.3 servings of fish, 2 servings of dairy (of which 1.4 servings are whole-fat dairy), 0.5 servings of red meat, and 0.3 servings of poultry per day.

During a median of 9.3 years of follow-up, when compared to those in the “least healthy score”, the “most healthy score” category was associated with incidence reductions of 30% for total mortality, 18% for CVD, 14% for MI, 19% for stroke, 28% in CVD mortality, and 32% for non-CVD mortality. 

Every point increase in the healthy diet score, an important yet achievable change, was associated with lower risk of total mortality (8%), major CVD (6%), MI (6%), stroke (6%), and composite of death or CVD (7%). These associations were present in both individuals with and without prior CVD.

In the combined analysis of the 5 prospective cohort studies, results indicated decreases in the risk of total mortality, major CVD, MI, stroke, and composite of CVD and death in all studies. 

Analyses comparing other dietary scores found that the Mediterranean, HEI-2010, HEI-2015, and DASH, but not the Planetary Health Index score, also showed beneficial associations with the measured health outcomes. However, the PURE score demonstrated the strongest associations with all outcomes compared to other dietary scores, particularly the Planetary Diet Index score. 

While the PURE score considers many foods that are included in other diet scores (e.g., fruits, vegetables, legumes, nuts, and fish), it also includes whole-fat dairy, based on the most recent scientific evidence. Importantly, the PURE score was predictive of outcomes in all world regions, while the other scores have been predominantly studied in Western contexts. Moreover, the PURE is the only score out of those included that exclusively features protective foods to encourage rather than foods or nutrients to limit. In light of their findings, the authors note that an inadequate consumption of healthy foods is likely a larger problem than the overconsumption of some nutrients and that the focus of many dietary guidelines and recommendations should be adapted as a consequence. Importantly, they also remark that some commonly discouraged nutrients, such as saturated fat, are consumed in lower levels in the “least healthy” diet than in the “most healthy” diet.

Overall, this study provides robust evidence that supports that a healthy diet comprised of fruits, vegetables, nuts, legumes, fish, and whole-fat dairy is associated with a decreased risk of CVD and mortality in all world regions.