Findings from more than 135,000 individuals from 18 low, middle and high-income countries in the Prospective Urban-Rural Epidemiology ( PURE ) study have shown that high carbohydrate intake is linked to worse total mortality and non-cardiovascular mortality outcomes, while high fat intake is associated with lower risk.
According to Mahshid Dehghan at McMaster University, in Hamilton, Ontario, Canada, the findings do not support the current recommendation to limit total fat intake to less than 30% of energy and saturated fat intake to less than 10% of energy.
Limiting total fat consumption is unlikely to improve health in populations, and a total fat intake of about 35% of energy with concomitant lowering of carbohydrate intake may lower risk of total mortality.
In fact, individuals with high carbohydrate intake, above 60% of energy, may benefit from a reduction in carbohydrate intake and increase in the consumption of fats.
PURE documented diet in 135,335 individuals, aged 35 to 70 years, from countries in North America and Europe, South America, the Middle East, South Asia, China, South East Asia and Africa.
For this analysis, consumption of carbohydrate, total fat and types of fat were recorded using country-specific, validated food frequency questionnaires, and associations were assessed with cardiovascular disease and mortality.
Among the 5,796 deaths and 4,784 major cardiovascular events over a median follow-up of 7.4 years, the researchers noted that carbohydrate intake in the highest versus lowest quintile was associated with a significant 28% increased risk of total mortality ( hazard ratio, HR=1·28; 95% CI 1·12-1·46, highest vs lowest quintile category, P less than or equal to 0·0001 ) but not cardiovascular disease ( CVD ) risk.
Conversely, total fat intake in the highest versus lowest quartile was associated with a significant 23% reduction of total mortality risk, an 18% reduced risk of stroke, and a 30% reduced risk of non-CVD mortality.
Each type of fat was associated with significantly reduced mortality risk: 14% lower for saturated fat, 19% for mono-unsaturated fat, and 20% for polyunsaturated fat.
Higher saturated fat intake was also associated with a 21% decrease in stroke risk.
The researchers also examined the impact of fats and carbohydrates on blood lipids in the same PURE study participants.
Consistent with other reports from Western countries, they found that while LDL increases with higher intakes of saturated fat, HDL also increases; so the net effect is a decrease in the total cholesterol/HDL ratio.
They found that LDL cholesterol ( the basis of many dietary guidelines ) is not reliable in predicting effects of saturated fat on future cardiovascular events. Instead, ApoB/ApoA1 provides the best overall indication of effect of saturated fat on cardiovascular risk among the markers tested.
For decades, dietary guidelines have focused on reducing total fat and saturated fatty acid ( SFA ) intake based on the presumption that replacing SFA with carbohydrate and unsaturated fats will lower LDL-C and should therefore reduce cardiovascular events.
But much of the evidence behind this approach has been from studies of Western populations where nutritional excess is a reality.
PURE provides a unique opportunity to study the impact of diet on total mortality and cardiovascular disease in diverse settings, some settings where over-nutrition is common and others where under nutrition is of greater concern. ( Xagena )
Source: ESC ( European Society of Cardiology ), 2017