Diet and Global Mortality
June 1, 2019
Clinical Assistant Professor, Department of Family Medicine, University of Wisconsin; Clinical Assistant Professor
of Medicine, Arizona Center for Integrative Medicine, University of Arizona, Tucson
Dr. Kiefer reports no financial relationships relevant to this field of study.
SUMMARY POINTS
- A global survey of 15 dietary factors (some positive, some negative) showed trends in unhealthy eating across geographic and demographic lines.
- An estimated 11 million people died in 2017 because of suboptimal eating habits.
- Most of the global diet-related health burden stemmed from high sodium intake and low intake of fruits and whole grains.
SYNOPSIS: Worldwide, there are alarming trends in unhealthy eating habits, which account for significant morbidity and mortality.
SOURCE: GBD 2017 Diet Collaborators. Health effects of dietary risks in 195 countries, 1990-2017: A systematic review for the Global Burden of Disease Study 2017. Lancet 2019;393:1958-1972.
Those of us in clinical practice are well-versed in addressing tobacco use and maximizing antihypertensive therapy. There are known, convincing consequences to those behaviors and conditions. Also, we are no strangers to the importance of nutrition. Most of us have grown up with “you are what you eat,” and there is now a large body of research to back that up, such as the Mediterranean diet and other nutritional approaches to health and disease. In recent years, authors for Integrative Medicine Alert have showcased these nutritional data. But what would it take to have food and nutrition take its place at the dinner table of major governmental guidelines, health policy decision-making, and the forefront of clinician-patient discourse? Perhaps the epidemiological study by the GBD 2017 Diet Collaborator research group, funded by the Bill and Melinda Gates Foundation and published in the April 3, 2019, edition of The Lancet, will serve that role.
To analyze the effect of diet on health, the researchers collected data on the intake of 15 foods and nutrients consumed by adults (25 years of age or older) in 195 countries. Their goal was to connect diet to chronic disease burden, so they also pooled data about mortality from noncommunicable diseases rather than death by other causes that may not be so closely tied to nutrition. The dietary factors chosen already had some data for a connection to health outcomes. (See Table 1.)
Table 1: 15 Dietary Factors Analyzed in This Global Disease Burden Study |
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Low Intake of … |
High Intake of … |
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Global surveys, primarily based on the 24-hour dietary recall, were searched to collect data on the consumption of these dietary factors for countries or smaller geographic areas using a variety of sources as detailed in the article. When possible, household budget information was noted, as were sales data (i.e., hydrogenated oils) or quantified physical data (i.e., urinary sodium). At times, the researchers had to estimate (guesstimate?) gender and age-specific results, extrapolating from nutritional data available for a country to the age/gender breakdowns for that country. Estimates were made based on the medical literature for each dietary factor’s optimal intake, and then whether people in each country were eating more or less of that nutrient or factor.
Then, the researchers paired dietary factors with a multitude of diseases and turned to the medical literature for quantified effects on mortality and morbidity. For some health conditions, such as type 2 diabetes and cardiovascular disease, they were able to specify the dietary effect on that disease process by age. Some estimates were indirect, such as the dietary effect of sodium. Urinary sodium implied excess sodium consumption, which is known to adversely affect blood pressure, and it is the hypertension literature that allowed a disease connection to be made. The researchers wove in diet, disease, age, gender, and year to comment on the mortality, as well as disability-adjusted life-years (DALYs).
The results showed that global intake of what the researchers called “healthy foods” was less than ideal; the lowest intakes were for whole grains, nuts, and milk. Geographically, the low-healthy-food trend was consistent across regions, except for adequate vegetable intake in central Asia, omega-3s in high-income areas of the Asian Pacific, and legumes in the Caribbean. In contrast, the “unhealthy” foods were ingested in amounts much higher than optimal levels, especially for sweetened beverages, sodium, and red and processed meats. Both types of foods (healthy and unhealthy) were consumed more by men and adults 50 to 69 years of age.
With respect to mortality and morbidity correlates, nutrition was linked to 11 million deaths globally in 2017, 10 million of which occurred because of cardiovascular disease, and almost 1 million from cancer. All told, this was estimated to be 22% of all adult deaths. The researchers also calculated that 225 million DALYs occurred because of nutritional reasons. The greatest negative effect of nutritional habits occurred in Oceania, whereas high-income Asia Pacific had the least rates of diet-related deaths and Australasia had the lowest rate of DALYs that occurred because of nutrition. By country, some standouts by category were apparent. (See Table 2.) The authors provided impressive color-coded charts and maps detailing these results, as well as some of the regional and disease-specific nuances by dietary factor.
Some nutrients were more important than others. Half of the deaths, and more than half of the DALYs, were attributable to high sodium intake and low fruit and whole grain consumption. There were some regional differences in nutrient intake that contributed to health outcomes, such as high sodium intake in Asia, low fruit intake in sub-
Saharan Africa, and low intake of nuts and seeds in Latin America. Incredibly detailed colorized pie charts explored these geographic variations.
Table 2: Countries That Scored Highest and Lowest for Diet-Related Deaths and DALYs |
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Deaths |
Overall highest |
Egypt |
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Overall lowest |
Japan |
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Cardiovascular highest |
China |
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Cardiovascular lowest |
Japan |
|
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Cancer highest |
China |
|
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Cancer lowest |
Egypt |
|
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Type 2 diabetes highest |
Mexico |
|
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Type 2 diabetes lowest |
Japan |
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|
Disability-adjusted life years (DALYs) |
Overall highest |
Egypt |
|
Overall lowest |
Japan |
|
|
Cardiovascular highest |
Egypt |
|
|
Cardiovascular lowest |
Japan |
|
|
Cancer highest |
China |
|
|
Cancer lowest |
Egypt |
|
|
Type 2 diabetes highest |
Mexico |
|
|
Type 2 diabetes lowest |
Japan |
|
The authors concluded that “…dietary risks affected people regardless of age, sex, and sociodemographic development of their place of residence.”
COMMENTARY
The researchers involved in this project confirmed on a global level what all people, whether in healthcare or not, know: Healthy nutrition is extremely important for health promotion and disease prevention. There were noted effects of eating less of the “healthy foods” and not enough of the “unhealthy foods” in all regions and for all age groups, but some areas had specific nutrient concerns. Perhaps there are cultural or economic factors that lead to, for example, suboptimal fruit intake in Sub-Saharan Africa or elevated sodium in Asia. If these results are to be believed, it would behoove both policymakers and healthcare practitioners to pay attention to these particular “weak links” and address them as the scope of their occupation allows.
Yes, this was an ambitious epidemiological study, as thorough as it could have been given the enormous scope of the project. The comprehensiveness of the survey sources was impressive, seemingly leaving no stone unturned. For example, it was impressive that the authors tied dietary sodium, when possible, to urinary sodium laboratory findings. That said, a study like this is only as good as the data available, and not all countries presumably had the facts necessary for a perfect analysis. Can we apply these results to the patients we see in clinic every day? Possibly. Does it provide some overarching themes and trends to help nudge our nutritional thinking on many healthcare levels? Definitely.
Obviously, the dietary connection to morbidity and mortality is one meaningful takeaway from this work. Another offshoot of their work is that they were able to estimate the “optimal intake” for a given nutrient, perhaps a guide for our patients interested in more specifics by nutrient. The table in their article provides these data and would be a useful reference for clinicians and patients alike, prompting the need for us non-metric users to convert some numbers.
The 15 dietary factors list also could be a starting point in discussing nutrition with patients. A wallet-size version, or even a poster on the clinic wall splitting the dietary factors into “Yes, eat more of these!” and “Please try to minimize these” could be a simple, risk-free nutritional step in the right direction for all of us. Furthermore, there is something empowering in thinking about the fact that “we’re all in this together,” that everyone around the globe, with some local particularities, is struggling with diet-related disease effects, hopefully ready to shift our food choices to the positive. This article may be the reminder, with some specific suggestions, about just how to do that.
Worldwide, there are alarming trends in unhealthy eating habits, which account for significant morbidity and mortality.
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