Global association of the PURE healthy diet score with health outcomes

Introduction and methods

Background

Unhealthy diets have been globally recognized to be an important contributing factor to CVD and death [1-2]. Previous studies that investigated the effects of diet on CVD and mortality have used different diet scores, and some data, for instance on exposure to whole-fat dairy, are conflicting [3-11]. Moreover, most studies with diet scores have been predominantly conducted in the USA, Europe and East-Asia, and it remains unknown whether the conclusions can be generalized to other world regions such as Africa, South America, Middle East or South Asia [12].

Aim of the study

The study aimed to:

(1) develop a healthy diet score from the large-scale, multinational, multicontinental Prospective Urban Rural Epidemiology (PURE) cohort;

(2) examine the consistency of the associations of PURE healthy diet score with events in 3 independent prospective studies and in 2 case-control studies of MI or stroke;

(3) determine whether consistent results with the PURE healthy diet score can be obtained with people from countries with various incomes, or from different regions of the world, and in people with and without CVD;

(4) compare the performance of the PURE healthy diet score with other commonly used diet score.

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Methods

The PURE study is an ongoing large-scale epidemiological cohort study that enrolled adults (35-70 years) from the general population in 21 low-, middle-, and high-income countries of 5 continents. Participants were enrolled in the study from 1 January 2003 to 31 July 2018, and outcome events that occurred before 31 July 2019 were included. For the current analysis, diet data from 147,642 participants were available. The median follow-up duration was 9.3 years. A total of 8201 MACE and 10,076 total deaths were reported.

The consistency of the PURE healthy diet score were validated in: (1) a cohort of 43,834 vascular patients from 3 prospective studies from 50 countries; (2) a cohort of 26,191 persons from 2 case-control studies of MI from 52 countries; and (3) a cohort of 26,930 persons from a case-control study of stroke from 33 countries. Collectively, 244,597 persons from 80 countries involving all inhabited continents with good representation of low-, middle-, and high-income countries were included. The division of participants from the different income countries was highly similar to the global distribution: in total 21% of participants were from high-income, 60% were from middle-income, and 19% were from low-income countries.

A healthy diet score was obtained on the basis of 6 food categories, each of which have been associated with a lower mortality-risk. These food categories consisted of fruit, vegetables, legumes, nuts, fish, and dairy (mainly whole-fat). The median food intake in the PURE study cohort was used as the cut-off value for assessing the score of each category. A score of 0 (unhealthy) was given to the category when the intake was at or below the cut-off value, and a score of 1 (healthy) was given when the intake was above the cut-off value. The PURE healthy diet score ranged from 0 to 6 (a higher score indicated a healthier diet).

Outcomes

The included outcomes were MACE (which consisted of fatal CVD, nonfatal MI, stroke and HF) and total mortality.

Main results

Diet definition

• A mostly healthy diet (score ≥5) consisted of 563.1 g/day of fruit and vegetables, 48.0 g/day of legumes, 28.2 g/day of nuts, 26.1 g/day of fish, and 185.5 g/day of dairy (of which 130.5 g/day is whole-fat dairy). The mostly healthy diet score also included 54.5 g/day of red meat, and 22.1 g/day of poultry.
• The diet with score ≤1 consisted of markedly lower amounts of intake of each food category. In contrast, diets with score 2-4 also had high intakes of fruit, vegetables and nuts, but differed in the consumption of the other food categories.

CV and total mortality

• The PURE healthy diet score of ≥5 was associated with a reduced risk of total mortality and cardiovascular events compared with the PURE healthy diet score of ≤1. There was a lower risk of total mortality (HR: 0.70; 95%CI: 0.63-0.77; P-trend<0.0001), major CVD (HR: 0.82; 95%CI: 0.75-0.91; P-trend<0.0001), MI (HR: 0.86; 95%CI: 0.75-0.99), stroke (HR: 0.81; 95%CI: 0.71-0.93), CVD mortality (HR: 0.72; 95%CI: 0.60-0.85), non-CVD mortality (HR: 0.68; 95%CI: 0.60-0.78), and the composite of death or CVD (HR: 0.78; 95%CI: 0.72-0.84; P-trend<0.0001). Similar association were found in persons with and without prior history of CVD.
• Removal of any of the component of the PURE healthy diet score generally resulted into weaker association between the diet score and the composite of CVD or death, suggesting that each component made a modest contribution to the score.
• The PURE healthy diet score performed similarly when unprocessed red meat or whole grains were included in the diet, suggesting that these component can be part of a healthy diet.
• The result of the PURE healthy diet score on outcome events showed consistent associations in other prospective studies.

Comparison with other dietary scores

• The PURE score showed slightly stronger association with death or CVD than other scores (Mediterranean, HEI-2010, HEI-2015, DASH, and Planetary Health scores) (P<0.001 for each comparison).

Subgroup analyses by income and geographic regions

• A higher PURE healthy diet score was associated with a lower risk of the composite of death or major CVD across all geographic regions and country income levels, but these association were stronger in South Asia, China, Africa, and in low-income countries.
• The mean PURE healthy scores in low-, middle-, and high-income countries were 2.2, 3.0, and 3.7, respectively.
• The mean PURE healthy score was 4.0 in North America and Europe, 2.9 in South America, 3.7 in the Middle East, 2.1 in South Asia, 3.1 in China/East Asia, 2.8 in Southeast Asia, 2.6 in Africa, and 3.9 in Australia/New-Zealand.

Conclusion

References

Find this article online at Eur Heart J.