Fat and Carbohydrate Intake and CV Mortality

Study Questions:

Are fats and carbohydrate intake associated with cardiovascular disease (CVD) in a large globally diverse cohort?

Methods:

Data were used from the PURE (Prospective Urban Rural Epidemiology) study, a large epidemiological cohort of adults aged 35-70 years, enrolled between 2003 and 2013, and who resided in 18 low-, middle-, and high-income countries on five continents. The three high-income countries were Canada, Sweden, and United Arab Emirates; 11 middle-income countries were Argentina, Brazil, Chile, China, Colombia, Iran, Malaysia, occupied Palestinian territory, Poland, South Africa, and Turkey; and four low-income countries were Bangladesh, India, Pakistan, and Zimbabwe. Diet was assessed using validated food frequency questionnaires. Participants were categorized into quintiles of nutrient intake (carbohydrate, fats, and protein) based on percentage of energy provided by nutrients. The primary outcomes of interest were total mortality and major CV events (including fatal CVD, nonfatal myocardial infarction [MI], stroke, and heart failure). Secondary outcomes included all MIs, stroke, CVD mortality, and non-CVD mortality.

Results:

A total of 135,335 participants were included in this analysis. Median follow-up was 7.4 years (interquartile range, 5.3–9.3), during which 5,796 deaths and 4,784 major CVD events were documented. Higher carbohydrate intake was associated with an increased risk of total mortality; with an increased risk hazard ratio (HR) 1.28 (95% confidence interval [CI], 1.12-1.46), for those in the highest quintile of carbohydrate consumption compared to those in the lowest quintile. In contrast, higher intake of total fat was associated with lower risk for total mortality (quintile 5 vs. quintile 1, total fat: HR 0.77; 95% CI, 0.67-0.87). A similar pattern was observed for saturated fat HR 0.86 (0.76-0.99), monounsaturated fat HR 0.81 (0.71-0.92), and polyunsaturated fat HR 0.80 (0.71-0.89). Higher saturated fat intake was associated with lower risk of stroke (quintile 5 vs. quintile 1, HR 0.79; 95% CI, 0.64-0.98) as well. Total fat and saturated and unsaturated fats were not significantly associated with risk of MI or CVD mortality.

Conclusions:

The authors concluded that high carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with CVD, MI, or CVD mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.

Perspective:

These data support the need for dietary recommendations which limit carbohydrate intake, in particular, refined carbohydrates.


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