Facts and Fictions: “The PURE Diet”

The release of the January 2025 dietary guidelines has contributed to ongoing conversations about ‘healthy eating.’ The ever-changing landscape may lead to confusion on the part of patients and healthcare professionals, but using shared decision-making strategies to discuss eating patterns can lead to increased adherence and improved patient outcomes.

How does research lead to changes in clinical practice? This article uses the lens of the 2016 PURE study (sometimes called the ‘PURE Diet’ in media reports) as an example of how new research is analyzed and recommendations for health are updated. Diet plan recommendations can be a moving target, and it is important to partner with patients to help navigate options and determine what is best for them.

Fact and Fictions: “The PURE Diet”

In the early part of the 21^st century, a healthy diet was often considered one that was low-fat, which translated into diets that were high in carbohydrates. Around 2016, data from the Prospective Rural Epidemiology (PURE) study was released, and the findings caused a stir. There was little agreement about what the results meant and what recommendations should be shared with patients.

The PURE study was a large, prospective, cohort study that enrolled 135,335 adults (35-70 years) from 18 countries on five continents from 2003-2013, with follow-up at about 7.4 years. Validated food frequency questionnaires were used to record dietary intake. Food intake (protein, fat, and carbohydrate) was categorized using quintiles, and the percentage of energy from nutrients was analyzed. Primary outcomes were total mortality and cardiovascular events such as heart failure, stroke, fatal cardiovascular disease, and non-fatal myocardial infarction.¹

Using hazard ratios and multivariate Cox modeling, the research found that a high carbohydrate intake (providing > 60% of energy) was correlated with an adverse impact on total mortality and on non-cardiovascular disease mortality. Additionally, findings included that higher fat intake was correlated with a lower risk of total and non-cardiovascular disease mortality as well as stroke.¹ The researchers summarized that the findings of the PURE study did not support the existing clinical dietary recommendations, which aimed to reduce total fat intake to less than 30%. Nor did the findings support the then-current guidelines on saturated fats.

Diving Into the Data

It is important to note that the PURE study was not a randomized control trial (RCT), which is often considered the gold standard for studying causal relationships.

Even though diet data from a large group of individuals was collected, there were still a lot of unanswered questions, namely:

• What about the relationship between specific animal products like meat or dairy and mortality?
• What about the possibility in some countries of both micronutrient-poor carbohydrates and micronutrient-rich meats being a confounder in the comparison of carbohydrate versus fat comparisons
• What is the role of high-carbohydrate diets in mortality?
• What are the associations between whole and refined grains, added sugars, and mortality?

Further research since the time of the PURE Study has led to current knowledge and understanding of the role of fats, carbohydrates, proteins, micronutrients, and even the gut biome, in healthy eating. Research has led to eating patterns such as DASH and the Mediterranean diet, which can contribute to improved patient health.

From Research to Practice

It is always a multi-faceted process to review scientific data and translate it into clinical practice, and into actions that patients take each day.

Consideration

Once research is released, important discussions occurs between researchers and clinicians to determine how applicable the findings are to prevention in the US. Guidelines committees, such as those coordinated by the American Heart Association and American College of Cardiology, gather experts to thoughtfully consider the applications of research into practice, and share information through scientific and policy statements, as well as creating new or updated guidelines.

Applying Guidelines to Practice

The next phase is applying the guidelines to practice. Preventive cardiovascular nurses are tasked with helping patients understand information about a wide range of topics and how to identify sources for accurate information. It might be argued that this task is exponentially more difficult today than it was during the time of the PURE study, thanks to the abundance of information available at people’s fingertips. The use of a shared decision-making process can help ensure that patients have a chance to voice their concerns, considerations, and goals, and work with their healthcare team to determine a sound, reasonable, and actionable course of action to which they can commit.

Clinical Takeaways

• Scientific research can lead to important questioning of long-held tenets, such as what constitutes a healthy diet for cardiovascular prevention.
• Helping patients to recognize trusted sources of information can support effective shared decision-making processes.
• While it takes a bit of time to incorporate the latest research into clinical guidelines, utilize the most updated guideline-directed medical therapies in treatment decisions.