By counting whole-fat dairy as a protective food, the new PURE Healthy Diet score strengthened the relationship between healthy eating and heart disease in a large study.
For individuals with and without cardiovascular disease (CVD), higher intake of protective foods (i.e., PURE diet score ≥5 points out of 6) compared with lower intake (diet score ≤1 point) was associated with lower risks in the PURE cohort spanning five continents with a median follow-up of 9.3 years, reported Andrew Mente, PhD, of the Population Health Research Institute at McMaster University in Hamilton, Ontario, and colleagues:
- All-cause mortality: HR 0.70 (95% CI 0.63-0.77)
- CVD: HR 0.82 (95% CI 0.75-0.91)
- Myocardial infarction: HR 0.86 (95% CI 0.75-0.99)
- Stroke: HR 0.81 (95% CI 0.71-0.93)
Unlike previous diet scores, the PURE Healthy Diet score does not penalize eating red meat. With a maximum score of 6, the PURE score simply awards one point each for above-median consumption of fruit, vegetables, nuts, legumes, fish, and whole-fat dairy.
PURE was found to be slightly more predictive of composite events than the Mediterranean, 2010 and 2015 Healthy Eating Index, and DASH diet scores — and substantially more predictive than the Lancet Planetary diet score, Mente and colleagues noted in the European Heart Journal.
“These findings suggest that an inadequate level of consumption of key healthy foods is a larger problem than over-consumption of some nutrients or foods (such as saturated fats or whole-fat dairy and meats — all of which are consumed in lower amounts with a lower diet score) for mortality and CVD risk around the world,” the authors wrote.
“On this basis, given the low intake of fats and especially saturated fat (i.e., whole-fat dairy) among people with the lowest diet score … current targeted dietary guidance limiting the consumption of saturated fat and dairy in many populations of the world may not be warranted,” they suggested.
Their results are in line with recent evidence showing that dairy may protect against high blood pressure and metabolic syndrome.
The new PURE score takes out the meat intake component that had been part of a prior dietary quality score from the PURE investigators. In 2018, they had reported that balanced consumption of various food groups, assessed by that older score, was linked to reduced CVD and mortality worldwide.
In their latest report, Mente and colleagues again stressed “variety and moderation” in a healthy diet. Whole grains and unprocessed meats may still be consumed in moderation, or about one serving daily, they recommended.
However, data for the new PURE score really only support targeting other foods, argued Dariush Mozaffarian, MD, DrPH, of Tufts Medical Center in Boston, in an accompanying editorial.
“The net health effects of unprocessed red meats remain uncertain — a high priority area for further investigation,” he wrote. “Based on current data, the authors’ findings and conclusions appear sound, providing evidence that unprocessed red meats are not a priority target for health to either avoid (as strongly emphasized by the EAT-Lancet report) or to include (as strongly emphasized by ‘paleo’ and ‘keto’ diets).”
Acknowledging that there is no one-size-fits-all approach to healthy eating across cultures, Mente’s group asserted that the PURE Healthy Diet generally translates to an eating pattern including:
- Fruits and vegetables: 4-5 servings daily
- Legumes: 3-4 servings weekly
- Nuts: 7 servings weekly
- Fish: 2-3 servings weekly
- Dairy: 14 servings weekly
A PURE score of 4 is the threshold for healthy eating beyond which there are modest additional gains in heart health and survival, they found. Thus, vegetarians and non-vegetarians alike may reach this score by consuming as many food groups as possible out of the six.
In the PURE cohort of 147,642 people on five continents, the mean PURE Healthy Diet score was 2.95.
Findings from this group were echoed across five independent cohorts: the ONTARGET, TRANSCEND, and ORIGIN trials; and the INTERHEART and INTERSTROKE case-control studies.
“This was by far the most diverse study of nutrition and health outcomes in the world and the only one with sufficient representation from high-, middle- and low-income countries. The connection between the PURE diet and health outcomes was found in generally healthy people, patients with CVD, patients with diabetes, and across economies,” Mente said in a press release.
Even so, Salim Yusuf, MBBS, DPhil, also of McMaster University and PURE’s principal investigator, stressed that associations were strongest in areas with the poorest-quality diet, where calorie intake was low and dominated by refined carbohydrates. “This suggests that a large proportion of deaths and CVD in adults around the world may be due to undernutrition, that is, low intakes of energy and protective foods, rather than overnutrition. This challenges current beliefs,” he said in a statement.
The PURE authors acknowledged that their observational study design left room for residual confounding. They also relied on self-reported diet data being accurate, coming from food frequency questionnaires.
“Ideally, large randomized trials are essential to definitively clarify the clinical impact on events of a policy of proposing a dietary pattern in populations. While such trials are difficult and expensive to conduct, they are justifiable given the important public health impact of clarifying the health effects of diet,” they wrote.
For now, Mozaffarian suggested that guideline recommendations to avoid whole-fat dairy should at least be re-evaluated.
“Investigations such as the one by Mente and colleagues remind us of the continuing and devastating rise in diet-related chronic diseases globally, and of the power of protective foods to help address these burdens,” he noted.
“It is time for national nutrition guidelines, private sector innovations, government tax policy and agricultural incentives, food procurement policies, labelling and other regulatory priorities, and food-based healthcare interventions to catch up to the science. Millions of lives depend on it,” he concluded.
The PURE study is an investigator-initiated study that is funded by the Population Health Research Institute, Hamilton Health Sciences Research Institute, the Canadian Institutes of Health Research, Heart and Stroke Foundation of Ontario, the Canadian Institutes of Health Research’s Strategy for Patient Oriented Research through the Ontario SPOR Support Unit, and the Ontario Ministry of Health and Long-Term Care, as well as through unrestricted grants from several pharmaceutical companies, with major contributions from AstraZeneca (Canada), Sanofi-Aventis (France and Canada), Boehringer Ingelheim (Germany and Canada), Servier, and GlaxoSmithKline, and additional contributions from Novartis and King Pharma and from various national or local organizations in participating countries.
Mente and colleagues had no relevant conflicts of interests.
Mozaffarian disclosed receiving research funding from the National Institutes of Health, the Gates Foundation, the Rockefeller Foundation, Vail Innovative Global Research, and the Kaiser Permanente Fund; personal fees from Acasti Pharma and Barilla; participation in scientific advisory boards for Beren Therapeutics, Brightseed, Calibrate, Elysium Health, Filtricine, HumanCo, Instacart Health, January Inc., and Perfect Day; equity in Calibrate and HumanCo; and chapter royalties from UpToDate.
European Heart Journal
Source Reference: Mente A, et al “Diet, cardiovascular disease, and mortality in 80 countries” Eur Heart J 2023; DOI: 10.1093/eurheartj/ehad269/7192512.
European Heart Journal
Source Reference: Mozaffarian D “Identifying nutritional priorities for global health: time for a more PURE focus on protective foods” Eur Heart J 2023; DOI: 10.1093/eurheartj/ehad325/7192538.
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