Globally, unhealthy diets have been recognised as a major cause of death and cardiovascular disease (CVD). Limitations to these reports include recommendations based on associations of individual foods, or nutrients or dietary patterns with CVD, and from studies conducted mostly in North America, Europe and East Asia, and otherwise numerous short-term randomized intervention trials of physiologic risk factors or clinical trials of dietary patterns on clinical outcomes. In diet score trials, consumption of foods that are believed to be protective have been compared with foods considered to be harmful. Thus, no diet score has focused exclusively on protective foods despite a recent increased focus on protective foods for disease prevention. Protective foods include fruit, vegetables, legumes, nuts and fish, and now also whole-fat dairy that previously was thought to increase CVD, but which recently has been shown to be either neutral or protective, and to a lesser extent also red meat. This comparatively new information has not yet been incorporated into nutrition guidelines. Additionally, it is not known whether conclusions drawn from diet score studies conducted predominantly in the USA, Europe and East Asia are applicable to other world regions such as Africa, South America, Middle East or South Asia, where dietary patters differ markedly.
As a consequence, the aims of the study cited were to (i) develop a healthy diet score from a large Prospective Urban Rural Epidemiology (PURE) cohort study involving 147 642 people from 21 countries in five continents; (ii) examine the consistency of the associations of the PURE healthy diet score with events in three independent prospective studies and two case-control studies of myocardial infarction or stroke, also both with large numbers in many countries; (iii) assess whether the PURE healthy diet score is applicable to people from high, medium and low income countries (numbers chosen according to the same ratio as globally), and to those with and without prior CVD, and (iv) compare the performance of the PURE healthy diet score with that of other commonly used diet scores (Mediterranean diet, HEI-2010 and 2015, DASH and Planetary Diet scores).
The healthy diet score was developed based on the six foods mentioned above, each of which has been associated with a significantly lower risk of mortality (range of scores 0-6). The main outcome measures were all-cause mortality and major cardiovascular events (CVD). During a median follow-up of 9.3 years in PURE, compared with a diet score of ≤1 points, a diet score of ≥5 points was associated with a lower risk of mortality [hazard ratio (HR) 0.70], CVD [HR 0.82], myocardial infarction [HR 0.86], and stroke [HR 0.81]. In the three independent studies in vascular patients, similar results were found, with a higher diet score associated with lower mortality (HR 0.73), CVD [HR 0.79] myocardial infarction [HR 0.85] and lower risk of stroke [HR 0 87]. Additionally, in the two case-control studies, a higher diet score was associated with lower first myocardial infarction [odds ratio (OR) 0.72] and stroke (OR 0.57). A higher diet score, furthermore, was associated with a significantly lower risk of death or CVD in regions with lower than with higher gross national incomes. Of significance is that the PURE score showed significantly stronger associations with death or CVD than the other common diet scores mentioned above (P <0.001 for each comparison).
The authors concluded that consumption of a diet comprised of higher amounts of fruits, vegetables, nuts, legumes, and a moderate amount of fish and whole-fat dairy, is associated with a lower risk of CVD and mortality in all regions of the world, but especially in countries with lower income where consumption of these natural foods is low. (Although not discussed, similar associations were found with the inclusion of meat or whole grain consumption in the normal ranges in the diet score). The findings imply that the risks of deaths and vascular events in adults globally are higher with inadequate intake of protective foods.
Comment: With respect to whole-fat dairy and to a lesser extend meat (red and white), this comprehensive study with countries worldwide and including high, medium and low incomes, showed unequivocally that animal foods should be included in diets of so-called protective foods against typical dietary derived diseases such as CVD. The study is impressive as 35 leading authors across the globe participated.