Toronto: Consuming a diet low in fats and high in carbohydrates may increase the risk of early death, according to a major global study that contradicts dietary advice handed out for decades.
The findings, published in The Lancet journal, may explain why certain populations such as South Asians, who do not consume much fat but eat a lot of carbohydrates, have higher mortality rates, researchers said.
The study on more than 135,000 people across five continents found that a diet which includes a moderate intake of fat and fruits and vegetables, and avoidance of high carbohydrates, is associated with lower risk of death. The lowest risk of death was in those people who consume three to four servings (or a total of 375 to 500 grammes) of fruits, vegetables and legumes a day, researchers said. The researchers from McMaster University and Hamilton Health Sciences in Canada asked people about their diet and followed them for an average of seven and half years. The study on dietary fats found that they are not associated with major cardiovascular disease, but higher fat consumption was associated with lower mortality.
This was seen for all major types of fats (saturated fats, polyunsaturated fats and mono unsaturated fats), with saturated fats being associated with lower stroke risk.
Total fat and individual types of fat were not associated with risk of heart attacks or death due to cardiovascular disease, researchers said.
While the finding may appear surprising to some, they are consistent with several observational studies and randomised controlled trials conducted in Western countries during the last two decades, they said.
The study questions the conventional beliefs about dietary fats and clinical outcomes, said Mahshid Dehghan, the lead author for the study.
"A decrease in fat intake automatically led to an increase in carbohydrate consumption and our findings may explain why certain populations such as South Asians, who do not consume much fat but consume a lot of carbohydrates, have higher mortality rates," she said.
Dehghan noted that dietary guidelines have focused for decades on reducing total fat to below 30 per cent of daily caloric intake and saturated fat to below 10 per cent of caloric intake.
This is based on the idea that reducing saturated fat should reduce the risk of cardiovascular disease, but did not take into account how saturated fat is replaced in the diet, she said. She added that the current guidelines were developed about four decades ago using data from some Western countries where fat was more than 40 per cent or 45 per cent of caloric intake and saturated fat intakes were more than 20 per cent.