Carbohydrates, not fats, increase total mortality

PURE is a major epidemiological study that followed 140,000 individuals in 18 countries for 7 years. Perhaps not a surprise that high carbohydrate intake was associated with 28% increased risk of total mortality, while total fats (saturated, monounsaturated and polyunsaturated) with 23% reduction.

Evidence is mounting that between the two excesses, fats are favored over carbohydrates, thus guiding the national and international movement toward taxation of sugary drinks.

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The Lancet

PURE study

August 2017

Background: The relationship between macronutrients and cardiovascular disease and mortality is controversial. Most available data are from European and North American populations where nutrition excess is more likely, so their applicability to other populations is unclear.

Methods: The Prospective Urban Rural Epidemiology (PURE) study is a large, epidemiological cohort study of individuals aged 35–70 years (enrolled Jan 2003 - March 2013) in 18 countries with a median follow-up of 7.4 years. Dietary intake of 135,335 individuals was recorded using validated food frequency questionnaires.

The primary outcomes were total mortality and major cardiovascular events (fatal CVD, non-fatal MI, stroke, and HF).

Secondary outcomes were all MIs, stroke, CVD mortality, and non-CVD mortality.

Participants were categorised into quintiles of nutrient intake (carbohydrate, fats, and protein) based on percentage of energy provided by nutrients. We assessed the associations between consumption of carbohydrate, total fat, and each type of fat with cardiovascular disease and total mortality. We calculated hazard ratios (HRs) using a multivariable Cox frailty model with random intercepts to account for centre clustering.

Findings: During follow-up, we documented 5796 deaths and 4784 major CVD events.

Higher carbohydrate intake was associated with an increased risk of TOTAL MORTALITY (highest [quintile 5] vs lowest quintile [quintile 1] category, HR 1·28 (p=0·0001) BUT NOT with the risk of CVD or CVD mortality.

Intake of total fat and each type of fat was associated with lower risk of total mortality; quintile 5 vs quintile 1,

Total fat: HR 0·77, p<0·0001;

Saturated fat, HR 0·86, p=0·0088;

Monounsaturated fat: HR 0·81, p<0·0001

Polyunsaturated fat: HR 0·80, p<0·0001

Higher saturated fat intake was associated with lower risk of stroke (quintile 5 vs quintile 1, HR 0·79, p=0·0498).

Total, saturated and unsaturated fats were not significantly associated with risk of MI or CVD mortality.

Interpretation: 

High carbohydrate intake was associated with higher risk of total mortality,

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,

Saturated fat had an inverse association with stroke.

Global dietary guidelines should be reconsidered in light of these findings.