It is no secret that lowering the amount of refined carbohydrates in the diet is associated with weight loss and better overall health. It is also no longer a secret that certain food corporations in the sugar industry promoted dietary fat as being harmful by funding research that falsely put the blame on fat for various diseases (1). More recently, this notion that dietary fat is harmful and is to blame for health problems is being put to rest. Many recent studies are not only showing that higher-fat, lower-carb diets help with weight loss, but also that the higher fat diets are associated with more favorable cardiovascular disease risk factors (blood pressure, lipids) (2). 

According to an August 2017 study in the Lancet (3), populations that had a high carbohydrate intake had a higher risk of death, while populations with higher total fat intake had a lower risk of death. The findings also indicated that fat intake is NOT associated with cardiovascular disease, heart attack, or death from cardiovascular disease. 

The Study:

This study, called the Prospective Urban Rural Epidemiology (PURE) study, followed 135,335 individuals ages 35-70 for over 7 years on average. The subjects in the study were from 18 different countries. The goal of the study was to analyze the risk factors associated with different diets throughout the world. Researchers monitored the 135,335 subjects and recorded their diets using food questionnaires. Throughout the study, total death and major cardiovascular events (heart attack, stroke, heart failure) were recorded and compared to the individuals' diets. 

This is what they found:

• Higher carbohydrate intake associated with increased risk of death, but not with the risk of cardiovascular disease
• Higher total fat intake associated with lower risk of death
• Each type of fat intake associated with lower risk of death 
• Higher saturated fat (found in animal products) associated with a lower risk of stroke
• Total fat, saturated fat, unsaturated fat all NOT associated with risk of heart attack or cardiovascular disease death

What does this mean?

Results from this extremely large cohort study should have major implications on rethinking nutritional guidelines . The results should also be used to further investigate these findings with high-quality studies. As with any population-based study, the results should not be taken as causative because the study only shows correlation. In order to demonstrate a causative relationship and further validate the findings, the results need to be paired with randomized-controlled trial studies. 

It is also important to understand that the results in this study did not note the quality of carbohydrate and fat intake, and there are many other factors. The types of carbohydrates and fats consumed and their balance is extremely important and was not discussed in this study.