Heart-Protective Diet in PURE Study Allows Whole-Fat Dairy

Marilynn Larkin July 11, 2023  Diet containing higher amounts of certain food categories appear to be protective against cardiovascular (CV) disease and premature death, suggests a new study with a broad international scope. Most of the protective food categories are in line with standard dietary guidelines for good health, but one that may be heart-protective is not usually included in such recommendations.

The food categories that were found to be protective include fruit, vegetables, nuts, legumes, and fish but also dairy, “mainly whole-fat,” in an analysis based on the international Prospective Urban and Rural Epidemiological (PURE) study and data from five other international trials that encompassed more than 240,000 people.

A healthy diet scoring system was derived from dietary patterns and clinical events observed in the PURE study and was applied to the populations of the other trials. Higher scores, corresponding to greater consumption of the six food categories, tracked with significantly reduced risks for death, myocardial infarction (MI), and stroke.

Reductions in mortality and CV-disease risk that were linked to the higher scores were especially pronounced in lower-income countries in the study published online July 6 in the European Heart Journal with lead author Andrew Mente, PhD, Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada.

The study in part refutes the frequent preference for low-fat or no-fat dairy foods over whole-fat dairy in healthy-diet recommendations. But it is consistent with earlier findings from PURE of reduced mortality risk with increased consumption of dietary fat, including saturated fat.

Whereas healthy-diet recommendations tend to emphasize reduced intake of fat, especially saturated fat, the report notes that “there are almost no national or international strategies and policies to increase a number of protective foods,” such as nuts, fish, and dairy.

“Therefore, while the findings from PURE are largely consistent with the nutrition science and modern dietary recommendations to focus on protective foods, the public’s understanding of healthy eating and relevant global policies have not yet caught up to this science,” it states.

“Guidelines and policy actions need to be updated with this newer evidence,” Mente told theheart.org/Medscape Cardiology. “For example, the World Health Organization remains mainly focused on reducing certain nutrients, such as fat, saturated fat, added sugar, and salt,” he said. “These recommendations are echoed by government policy actions and industry, as evident by the continued focus on the usual nutrients in food labels of many countries.”

The current findings, Mente said, “can be used to ensure that the public’s understanding of healthy eating and relevant global policies are able to catch up to the science.”

Healthy Diet Score

PURE investigators developed their healthy diet score using data from 147,642 people from the general population in 21 countries. The investigators compared self-reported dietary intakes with long-term clinical outcomes.

The scoring system assigned a value of 1 for each of the six health-food categories when individuals’ intake exceeded the entire cohort’s median intake. It assigned a 0 when intake was below the median. The total PURE healthy diet score consisted of the sum of the six values, with higher scores corresponding to a healthier diet. The mean score for cohort was 2.95.

There were 15,707 deaths and 40,764 CV events during a median follow-up of 9.3 years. A score of at least 5 points, compared with 0 or 1 point, was associated with significantly reduced hazard ratios (HRs) for mortality, MI, and stroke in multivariable analysis:

• Mortality: HR, 0.70 (95% CI, 0.63 – 0.77; P < .0001)
• Major CV disease: HR, 0.82 (95% CI, 0.75 – 0.91; P < .0001)
• MI: HR, 0.86 (95% CI, 0.75 – 0.99; P = .0014)
• Stroke: HR, 0.81 (95% CI, 0.71 – 0.93; P = .0034)

The healthy diet score’s relationship to clinical outcomes was explored in five other large independent studies, including three prospective trials of patients with CV disease that spanned 50 countries, a case-control study with MI patients in 52 countries, and a case-control study with stroke patients in 33 countries.

In the three prospective trials, higher scores were associated with reduced mortality, CV disease events, and MI:

• Mortality: HR, 0.73 (95% CI, 0.66 – 0.81)
• Major CV disease: HR, 0.79 (95% CI, 0.72 – 0.87)
• MI: HR, 0.85 (95% CI, 0.71 – 0.99)

In the two case-control studies, a higher diet score was associated with reduced odds ratios (ORs) for first MI and for stroke:

• MI: OR, 0.72 (95% CI, 0.65 – 0.80)
• Stroke: OR, 0.57 (95% CI, 0.50 – 0.65)

In an analysis based on the PURE cohort, incorporation of unprocessed red meat or whole grains into the health diet score produced similar results, suggesting that a “modest amount” of meat or whole grains can be part of a healthy diet, the authors contend.

The results were similar in a combined analysis of all the prospective studies. In particular, improvement in diet score by one quintile was associated with significantly reduced risks for the following:

• Mortality: HR, 0.92 (95% CI, 0.90 – 0.93)
• Major CV disease: HR, 0.94 (95% CI, 0.93 – 0.95)
• MI: HR, 0.94 (95% CI, 0.92 – 0.96)
• Stroke: HR, 0.94 (95% CI, 0.89 – 0.99)
• Death or CV disease: HR, 0.93 (95% CI, 0.92 – 0.94)

“This strongly indicates that the take-home message for patients is the same as for general populations,” Mente said. “Eat plenty of fruits, vegetables, nuts, legumes, and a moderate amount of fish and whole-fat dairy to lower risk of CV disease and mortality.”

“Many other dietary patterns have been identified over the years that also do a great job in predicting disease risk in observational studies,” observed Sesso. “Is PURE that much better? Maybe, maybe not. But not enough to dismiss other dietary patterns that are already the basis of dietary recommendations in the US, Europe, and worldwide.”

The PURE healthy diet score, he said, “appears to work well within the confines of their large pooling of studies around the world, but that doesn’t automatically make it superior to other dietary patterns.” The score “was only modestly, but not greatly, better than existing dietary patterns evaluated.”

A diet comprised of higher amounts of fruit, vegetables, nuts, legumes, fish, and whole-fat dairy is associated with lower CVD and mortality in all world regions, especially in countries with lower income where consumption of these foods is low.

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