Why West’s low-fat diet advice could be deadly for Asia’s poor, because they’ll likely eat even more carbs
Telling people already on a high-carb, low-fat diet to eat less fat will only get them eating even more carbs – increasing their risk of death – because of the high cost of fruit and vegetables, say researchers
Widely promoted guidelines to reduce fat intake could be unhealthy for people in low- and middle-income countries whose diets are already too starchy, say researchers.
Health authorities in Europe and North America recommend eating more fruit and vegetables while curtailing consumption of fatty foods, advice also adopted by the United Nations and globally.
But people in poor nations cutting back on fat may wind up piling on more carbohydrates – such as potatoes, rice or bread – because fruit and vegetable are more expensive, the authors point out.
“The current focus on promoting low-fat diets ignores the fact that most people’s diets in low- and middle-income countries are very high in carbohydrates, which seem to be linked to worse health outcomes,” says Mahshid Dehghan, a researcher at McMaster University in Ontario, Canada, and lead author of a study in The Lancet.
Meanwhile, a companion study, also published in The Lancet, concludes that the rich-world guidelines – backed by the World Health Organisation – on fruit and vegetable consumption could be safely cut back from five to a more affordable three portions per day.
Dehghan and her colleagues sifted through the health data of 135,000 volunteers from 18 countries across six continents, aged 35 to 70, who were monitored for 7½ years.
People who met three-quarters or more of their daily energy needs with carbs were 28 per cent more likely to die over that period than those whose diet comprised a lower proportion of starchy foods (46 per cent or less of energy needs).
Surprisingly, the findings also challenged assumptions on fat intake: diets high in fat (35 per cent of energy) were linked with a 23 per cent lower risk of death compared to low-fat diets (11 per cent of energy).
“Contrary to popular belief, increased consumption of dietary fats is associated with a lower risk of death,” Dehghan says.
That covered a mix of saturated fats (from meats and milk products), along with monounsaturated and polyunsaturated fats (from vegetable oils, olive oil, nuts and fish). The study did not look at so-called “trans fats” from processed foods because “the evidence is clear that these are unhealthy”, says Dehghan.
The best diets include a balance of 50 per cent to 55 per cent carbohydrates and about 35 per cent total fat, according to the authors, who presented their findings at the European Society of Cardiology Congress in Barcelona.
Current global guidelines – based mostly on studies done in Europe and the US – recommend that 50-65 per cent of one’s calories come from carbs, and less than 10 per cent from saturated fats.
Overall, the study found that the average diet consists of just more than 61 per cent carbohydrates, 23.5 per cent “good” fat, and 15 per cent protein.
But these averages hid important regional imbalances: in China, South Asia and Africa, intake of starchy foods was 67 per cent, 65 per cent and 63 per cent, respectively.
A quarter of the 135,000 subjects – mostly in poorer nations – derived more than 70 per cent of their daily calories from carbohydrates, while half had less than seven per cent saturated fats in their diet.
The findings “challenge conventional diet-disease tenets” largely based on the lifestyles of Europeans and Americans, Christopher Ramsden and Anthony Domenichiello comment wrote in The Lancet.
Dehghan and colleagues set out to look for links between diet and cardiovascular disease, which kills about 17 million people around the world each year – 80 per cent of them in low- and middle-income countries.
Many factors contribute to these diseases but diet is one of the few that can be modified to lessen risk.
While high-carb and low-fat diets were clearly associated with greater mortality, no statistical link was found with the kind of life-threatening events – strokes, heart attacks, and other forms of heart failure – that stem from cardiovascular disease.
Susan Jebb, a professor at the University of Oxford who did not take part in the study, said the reported link between high-carb diets and excess mortality “was from non-cardiovascular deaths and is unexplained”.