BACKGROUND AND PURPOSE: 

• The correct balance of carbohydrate vs fat intake remains a hotly debated topic with respect to adverse cardiovascular outcomes
• Dehghan et al. (Lancet, 2017) prospectively analyzed data from 18 different countries to understand the health impact of high fat and carbohydrate diets on a more global scale 

METHODS: 

• Data was derived from the Prospective Urban Rural Epidemiology (PURE), which follows the dietary intake of individuals aged 35-70 years of age in 18 different countries with follow-up
• Participants were categorized into quintiles based on the amount of energy derived from their diet (carbohydrate, fats, and protein) 
• Primary outcomes were total mortality and major cardiovascular events 
• Secondary outcomes were all myocardial infarctions, stroke, cardiovascular disease mortality, and non-cardiovascular disease mortality 

RESULTS: 

• 135,335 individuals were included in this analysis with median follow-up of 7.4 years  
• Higher carbohydrate intake was associated with an increased risk of total mortality (highest quintile vs lowest quintile hazard ratio [HR] 1.28; 95% CI 1·12–1·46, p_trend  = 0.0001) 
  • Not associated with a risk for cardiovascular disease or cardiovascular disease mortality 
• Fat intake was associated with reduced mortality risk comparing highest to lowest quintile  
  • Total fat: HR 0.77 (95% CI 0·67–0·87; p_trend = 0.0001) 
  • Saturated fat: HR 0.86 (95% CI 0.76–0.99; p_trend = 0·0088) 
  • Monounsaturated fat: HR 0.81 (95% CI 0.71–0.92; p_trend = 0.0001) 
  • Polyunsaturated fat: HR 0.80 (95% CI 0.71–0.89; p_trend = 0.0001) 
• Higher saturated fat intake was associated with less risk of stroke, comparing highest to lowest quintile (HR 0.79 95% CI 0.64–0.98; ptrend = 0.0498) 
• Saturated and unsaturated fats were not significantly associated with risk of myocardial infarction or cardiovascular disease mortality 

CONCLUSION: 

• High carbohydrate diet (more than approximately 60% of energy intake) may lead to higher risk of mortality, although not due to greater risk for adverse cardiovascular events 
• Total fat and types of fats were not associated with higher risk of mortality, stroke, myocardial infarction, or cardiovascular disease mortality  
• Researchers, using replacement analyses, demonstrated the greatest impact in total mortality association when carbohydrate intake was replaced with polyunsaturated fatty acid intake 
• PURE study data consistent with other recent studies demonstrating no association between fats and higher cardiovascular disease or mortality 
• Nutrients have varying effects on different lipid fractions
  • Clinical effects of energy intake needs to be based on other lipid fractions and not only LDL cholesterol

Learn More – Primary Sources:

Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study

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