In 2017, more deaths were caused by diets containing too low amounts of foods such as whole grains, fruit, nuts, and seeds, than by diets with high levels of sugar, trans fats and red and processed meats. People in almost every region of the world could benefit from rebalancing their diets to eat optimal amounts of various foods and nutrients, according to the Global Burden of Disease study tracking trends in consumption of 15 dietary factors from 1990 to 2017 in 195 countries, published in the Lancet medical journal, Science Daily said on April 3, 2019.
The study estimates that one in five deaths globally or 11 million deaths, are associated with poor diet, and diet contributes to a range of chronic diseases in people around the world.
The authors said that their findings highlight the urgent need for coordinated global efforts to improve diet, through collaboration with various sections of the food system and policies that drive balanced diets.
"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 study author Dr. Christopher Murray, director of the Institute for Health Metrics and Evaluation, University of Washington, USA.
"While sodium, sugar, and fat have been the focus of policy debates over the past two decades, our assessment suggests the leading dietary risk factors are a high intake of sodium, or low intake of healthy foods, such as whole grains, fruit, nuts and seeds, and vegetables.
The paper also highlights the need for comprehensive interventions to promote the production, distribution, and consumption of healthy foods across all nations."
Impact of diet on non-communicable diseases and mortality
The study evaluated the consumption of major foods and nutrients across 195 countries and quantified the impact of poor diets on death and disease from non-communicable diseases (specifically cancers, cardiovascular diseases, and diabetes).
Previously, population-level assessment of the health effects of suboptimal diet has not been possible because of the complexities of characterizing dietary consumption across different nations. The new study combines and analyses data from epidemiological studies -- in the absence of long-term randomized trials which are not always feasible in nutrition -- to identify associations between dietary factors and non-communicable diseases.
The study looked at 15 dietary elements -- diets low in fruits, vegetables, legumes, whole grains, nuts and seeds, milk, fiber, calcium, seafood omega-3 fatty acids, polyunsaturated fats, and diets high in red meat, processed meat, sugar-sweetened beverages, trans fatty acids, and sodium.
The authors note that there were varying levels of data available for each dietary factor, which increases the statistical uncertainty of these estimates -- for example, while data on how many people ate most dietary factors was available for almost all countries (95 percent), data for the sodium estimates were only available for around one in four countries.
Overall in 2017, an estimated 11 million deaths were attributable to poor diet. Diets high in sodium, low in whole grains, and low in fruit together accounted for more than half of all diet-related deaths globally in 2017.
The causes of these deaths included 10 million deaths from cardiovascular disease, 913,000 cancer deaths, and almost 339,000 deaths from type 2 diabetes. Deaths related to diet have increased from 8 million in 1990, largely due to increases in the population and population aging.
Global trends in consumption
The authors found that intakes of all 15 dietary elements were suboptimal for almost every region of the world -- no region ate the optimal amount of all 15 dietary factors, and not one dietary factor was eaten in the right amounts by all 21 regions of the world.
Some regions did manage to eat some dietary elements in the right amounts. For example, intake of vegetables was optimal in central Asia, as was seafood omega-3 fatty acids intake in the high-income Asia Pacific, and legume intake in the Caribbean, tropical Latin America, South Asia, western sub-Saharan Africa, and eastern sub-Saharan Africa.
The largest shortfalls in optimal intake were seen for nuts and seeds, milk, whole grains, and the largest excesses were seen for sugar-sweetened beverages, processed meat, and sodium. On average, the world only ate 12 percent of the recommended amount of nuts and seeds (around 3g average intake per day, compared with 21g recommended per day), and drank around ten times the recommended amount of sugar-sweetened beverages (49g average intake, compared with 3g recommended).
In addition, the global diet included 16 percent of the recommended amount of milk, about a quarter (23 percent) of the recommended amount of whole grains, almost double (90 percent more) the recommended range of processed meat, and 86 percent more sodium.
The magnitude of diet-related disease highlights that many existing campaigns have not been effective, and the authors called for new food system interventions to rebalance diets around the world. Importantly, they noted that changes must be sensitive to the environmental effects of the global food system to avoid adverse effects on climate change, biodiversity loss, land degradation, depleting freshwater, and soil degradation.
The authors noted some limitations of the current study, including that while it uses the best available data, there are gaps in nationally representative individual-level data for the intake of key foods and nutrients around the world.
Writing in a linked comment, Professor Nita G Forouhi, Medical Research Council Epidemiology Unit, University of Cambridge School of Clinical Medicine, UK, said: "Limitations notwithstanding, the current GBD findings provide evidence to shift the focus, as the authors argue, from an emphasis on dietary restriction to promoting healthy food components in a global context. This evidence largely endorses a case for moving from nutrient-based to food-based guidelines.”
In January 2019, The Lancet published the EAT-Lancet Commission, which provides the first scientific targets for a healthy diet from a sustainable food production system that operates within planetary boundaries for food. This report used 2016 data from the Global Burden of Disease study to estimate how far the world is from the healthy diet proposed.