- Dietary risks were associated with 11 million deaths in 2017—about one in every five deaths globally—and the loss of 255 million years of life due to poor health.
- More than half of these 11 million deaths were associated with three top risk factors: eating too much salt, not eating enough whole grains and not eating enough fruit. These risks were followed by diets low in nuts and seeds, vegetables, and omega-3 fatty acids.
- The number of deaths attributed to high consumption of red and processed meat, trans fat and sugar-sweetened beverages was lower than the above dietary components for most countries with higher populations.
In the nonstop nutrition news cycle, it’s common to hear about studies linking excessive intakes of sugar, salt and certain types of fat to unhealthy lifestyles and a risk for many adverse health conditions. But what if it’s not that simple? A new study published in the Lancet and funded by the Bill and Melinda Gates Foundation is shaking up the narrative around what we eat and our risk for diet-related diseases. Is what we’re not eating more important than what we’re eating too much of?
How Was the Study Done?
The study in question is part of the Global Burden of Disease report (GBD), which is published yearly by a group of thousands of collaborators across the world. The GBD aims to help countries and their policymakers understand their population’s health challenges and track changes over time in an effort to improve their health care systems and eliminate disparities. The GBD tracks death and disability from more than 350 diseases and injuries in 195 countries.
In this study, authors selected 15 dietary components, including things like intake of fruits, vegetables, red and processed meat, fiber, omega-3s and sodium. Then they collected data on dietary intake, sales of foods and beverages and availability of foods and nutrients in each of the 195 countries included in the GBD. They collected information on disease-specific deaths and disability from the GBD 2017 report and used statistical analysis and modeling to estimate the relationships that the 15 dietary components had with deaths and disability.
What Were the Results?
Certain dietary components were associated with 11 million deaths in 2017—about one in every five deaths globally. Ten million of these deaths were caused by cardiovascular disease, followed by diet-related cancers at over 900,000 deaths and type 2 diabetes at 339,000 deaths. Dietary risks were associated with 255 million years of life lost due to poor health.
More than half of all diet-related deaths in 2017 were connected to three top risk factors: eating too much salt, not eating enough whole grains and not eating enough fruit. Diets low in nuts and seeds, vegetables and omega-3 fatty acids also contributed substantially to diet-related deaths. Low intake of whole grains was the leading dietary risk factor for mortality among women, while high sodium intake was the highest risk factor for men.
A somewhat unexpected finding of this study was that the number of deaths attributed to high consumption of red and processed meat, trans fat and sugar-sweetened beverages was lower than the above dietary components for most countries with higher populations. These risks held steady regardless of socioeconomic level for most countries. Region- and country-specific information can be found in the full publication.
Study Strengths and Limitations
Undoubtedly, one of the strengths of this study is the vast amount of data collected and the global nature of the information. The sample size is very large, spans countries across the globe and includes a wide variety of socioeconomic indicators. All of these assets enhance the relevance of the results to all people, whether or not they live in the United States, Bangladesh or Latin America.
At the same time, there are also downsides to the wide breadth of this study. Dietary data were collected from many different sources with varying degrees of response rates and accuracy, and the same information was not available for all 195 countries. This fact increases the statistical uncertainty of the estimates made in the study. There are also gaps in our knowledge of food and nutrient intake in different regions of the world, since not all countries have established tracking systems for diet and health indicators like the U.S. has with NHANES. For example, sodium intake estimates were not available in many countries.
Of course, our favorite and most common limitation applies to this study as well: the information in this report comes from observational studies and economic reports—not from higher-quality evidence found in randomized controlled trials. This means that although there may be a connection between self-reported dietary intake and disease risk, we can’t prove that overall diet or any one specific nutrient caused death or disability. And since the GBD combined many, many different sets of data, there’s additional risk for measurement errors, confounding and bias—all of which may lead to the reported results differing from true estimates.
Although in recent years the overconsumption of foods and beverages high in sugar, trans fats and red and processed meats has been the focus of many studies and public health awareness campaigns, this new research offers a sharply different angle: that the lack of healthy foods in our diets may be even more important than the overconsumption of unhealthy foods. The exception to this, however, is habitual high sodium intake, which has been consistently linked to increased risk of high blood pressure, which in turn is a risk factor for cardiovascular disease. As this study demonstrated, the vast majority of diet-related deaths were due to cardiovascular disease, so efforts to reduce the amount of sodium in our diet will continue to be important topics of discussion in public health and food policy arenas.
All of this isn’t to say that eating too much sugar or unhealthy fats doesn’t matter. But a study like this gives us the rare opportunity to focus on what we can add to our meals to improve our health, instead of the usual “what can’t I eat?” approach. Emphasizing intakes of foods like fruits, vegetables, whole grains, seafood, nuts and seeds as the backbone of a healthy diet isn’t a new concept, but a study like this highlights the critical importance of doing so.