April 17, 2019
People in almost every global region and income bracket would do well to recalibrate their diets — not only to reduce sugar and sodium but also to boost intakes of whole grains and fruits.
In fact, of the 11 million deaths in 2017 attributed to dietary factors, more were associated with inadequate intakes of healthy foods than with superfluous consumption of unhealthy ones, according to the Global Burden of Disease 2017 (GBD 2017) study, published online April 3 in The Lancet.
Righting that dietary imbalance might potentially prevent more than 1 in 5 deaths worldwide.
Globally, the largest deficiencies in healthy food consumption were related to nuts, seeds, milk, and whole grains, whereas sugary drinks, processed meats, and sodium were overconsumed. The findings are based on combined analyses of data from epidemiologic studies.
"Although sodium, sugar, and fat have been the main focus of diet policy debate in the past two decades, our assessment shows that the leading dietary risk factors for mortality are diets high in sodium, low in whole grains, low in fruit, low in nuts and seeds, low in vegetables, and low in omega-3 fatty acids; each accounting for more than 2% of global deaths," the GBD 2017 diet collaborators write.
They report that while the effect of specific dietary factors differed across countries, nonoptimal consumption of whole grains, fruits, and sodium accounted for more than 50% of deaths and 66% of disability-adjusted life years (DALYs) attributable to diet. This conclusion emerged from their examination of the impact on noncommunicable diseases of 15 dietary components from 1990 to 2017 in 195 countries across 21 regions.
"This finding highlights the urgent need for coordinated global efforts to improve the quality of human diet," the authors write. "Given the complexity of dietary behaviours and the wide range of influences on diet, improving diet requires active collaboration of a variety of actors throughout the food system, along with policies targeting multiple sectors of the food system."
Looking at the mean daily consumption patterns of people age 25 years or older, the investigators identified the 15 relevant dietary factors as:
- diets low in fruits, vegetables, legumes, whole grains, milk, nuts and seeds, fiber, calcium, seafood-derived omega-3 fatty acids, and polyunsaturated fatty acids
- diets high in red meats, processed meats, trans fatty acids, sugary drinks, and sodium
Estimating the number of diet-linked deaths and DALYs for various diseases, the authors note that in 2017, 22% of the adult deaths and 15% of DALYs (255 million) could be ascribed to dietary risk factors. Cardiovascular disease was the biggest driver of mortality with 10 million deaths, followed by cancer with 913,090 deaths, and type 2 diabetes with 338,714 deaths.
"This study affirms what many have thought for several years — that poor diet is responsible for more deaths than any other risk factor in the world," said corresponding author Christopher Murray, MD, director of the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, in a Lancet news release.
By individual risk factor, sodium intake topped the global list of dietary culprits with 3 million deaths and 70 million DALYs attributed to it. Next was low intake of whole grains with 3 million deaths and 82 million DALYs, followed by low fruit intake with 2 million deaths and 65 million DALYs. The authors acknowledge, however, that these data derive from mixed sources and were not available for all countries, increasing the potential for statistical uncertainty.
Israel had the lowest rate of diet-related deaths (89 per 100,000 population); Uzbekistan had the highest rate of (892 per 100,000). The United States ranked 43rd (171 deaths per 100,000). The Oceania region (Australia, New Zealand, South Pacific islands) also ranked very high with 678 deaths per 100,000. For type 2 diabetes, high-income North America had the highest age-standardized rates of deaths (41%) and DALYs (50%).
While acknowledging the value of the GBD risk estimates, the authors of a related commentary stress the mixed sources of the data and the unavailability of data from some world regions. They also point out that the findings are based on populations largely of European descent.
"Therefore, generalisability of dietary risks and outcome relationships is questionable, and potential heterogeneity across populations is ignored," write Nita G. Forouhi, MD, of the University of Cambridge's Medical Research Council Epidemiology Unit in the United Kingdom, and Nigel Unwin, MD, PhD, of the George Alleyne Chronic Disease Research Centre at the University of the West Indies, in Bridgetown, Barbados.
"The use of summary risk estimates in the study fails to account for such differences, which could reflect differences in food preparation, environmental factors, or confounding structure," the commentators write.
Nonetheless, they add, the study offers evidence for shifting the emphasis from negative dietary restriction to the positive promotion of healthy foods. "This evidence largely endorses a case for moving from nutrient-based to food-based guidelines," they write, adding that the findings reinforce those of the EAT–Lancet Commission which calls for healthier diets through sustainable food systems and largely plant-based diets.
The commentators note, however, that a serious barrier to such change is the prohibitive cost of fruits and vegetables in lower-income countries. For example, two servings of fruits and three servings of vegetables per day per individual accounted for 52% of household income in low-income countries and 18% in low- to middle-income countries.
A major overhaul in food systems is required. "A menu of integrated policy interventions across whole food systems, internationally and within countries, is essential to support the radical shift in diets needed to optimise human, and protect planetary, health," Forouhi and Unwin write.
This study was funded by the Bill & Melinda Gates Foundation. Several GBH collaborators disclosed ties to private-sector companies, including Amgen, Berlin-Chemie, Merck Sharp & Dohme, Novo Nordisk, sanofi-aventis, Synlab, Unilever, and Upfield. A complete list is available on the journal's website. The editorial commentators have disclosed no relevant financial relationships.