Excessive carbs—not fats—pose greatest dietary risk

Researchers at the European Society of Cardiology Congress are urging a rethink of global dietary guidelines in light of new data.

They say carbohydrates, not fats, are most important to limit.

In a study of more than 135,000 adults spanning five continents and all income ranges, researchers showed high carbohydrate intake is associated with worse total mortality and non-cardiovascular mortality outcomes, while high fat intake is linked to lower risk.

“Our findings do not support the current recommendation to limit total fat intake to less than 30 percent of energy and saturated fat intake to less than 10 percent of energy,” study investigator Mahshid Dehghan, PhD, from the Population Health Research Institute, McMaster University, in Hamilton, Ontario, Canada, said in a statement. “Limiting total fat consumption is unlikely to improve health in populations, and a total fat intake of about 35 percent of energy with concomitant lowering of carbohydrate intake may lower risk of total mortality. In fact, individuals with high carbohydrate intake, above 60 percent of energy, may benefit from a reduction in carbohydrate intake and increase in the consumption of fats.”

In the analysis, consumption of carbs, fats and types of fat were recorded using country-specific food frequency surveys, and associations were assessed with cardiovascular diseases (CVD) and mortality.

Individuals in the top quintile of carb intake had a 28 percent increased risk of total mortality when compared to the lowest quintile, but showed no significant increase of CVD risk.

Fat intake in the highest versus lowest quartile was associated with risk reductions of 23 percent for total mortality, 18 percent for stroke and 30 percent for non-CVD mortality. Polyunsaturated fat intake showed the greatest reduction of risk for mortality at 20 percent, followed by 19 percent for mono-unsaturated fat and 14 percent for saturated fat. Higher saturated fat intake was also associated with a 21 percent decrease in stroke risk.

The researchers noted high saturated fat intake increases both forms of cholesterol—“bad” low-density lipoprotein (LDL) but also “good” high-density lipoprotein (HDL), which provides a protective effect.

They suggested current dietary guidelines may have been influenced by a disproportionate amount of studies from Western countries where nutritional excess is more likely.

The present research “provides a unique opportunity to study the impact of diet on total mortality and CVD in diverse settings, some settings where over-nutrition is common and others where under nutrition is of greater concern,” Dehghan said.