A Deadly Diet: Half of US Deaths From Cardiometabolic Causes Linked to Dietary Habits

Nearly half of all deaths from heart disease, stroke, and type 2 diabetes mellitus in the United States are attributable to a poor diet, suggest the results of a new study.  

In an analysis of more than 700,000 cardiometabolic deaths in 2012, which includes deaths from coronary, hypertensive, and other forms of cardiovascular disease, as well as from stroke and type 2 diabetes, 45.4% were related to specific dietary habits.

“And, it wasn’t just too much ‘bad’ in the American diet; it’s also not enough ‘good,’” lead investigator Renata Micha, PhD (Tufts Friedman School of Nutrition Science and Policy, Boston, MA) told TCTMD. “Americans are not eating enough fruits, vegetables, nuts/seeds, whole grains, vegetable oils, or fish. Americans are overeating salt, processed meats, and sugary-sweetened beverages. This is especially true of men, younger adults, Blacks and Hispanics, and people with lower levels of education.”

Senior investigator Dariush Mozaffarian, MD (Tufts Friedman School of Nutrition Science and Policy) said the US is currently facing a “nutrition crisis.”

“Few other challenges cause more deaths, disability, and associated preventable health costs,” he commented to TCTMD via email. “While Congress is actively debating on how to improve health and reduce costs, fixing our food system is among the most essential priorities, a win-win for all.”

Estimation of Cardiometabolic Impact 10 Dietary Factors 

Published March 7, 2017 in the Journal of the American Medical Association, the researchers assessed population demographics and dietary habits by age, sex, race, and education from the National Health and Nutrition Examination Survey (NHANES) and estimated the association of 10 foods and nutrients with heart disease, stroke, and type 2 diabetes mortality from meta-analyses and randomized trials.

The 10 foods and nutrients included fruits, vegetables, nuts/seeds, whole grains, unprocessed red meats, processed meats, sugar-sweetened beverages, polyunsaturated fats, seafood omega-3 fatty acids, and sodium. The optimal intake of these dietary factors was based on the observed intakes associated with the lowest risk of cardiometabolic mortality in observational studies.

Using data from the National Center for Health Statistics, they estimated that 702,308 individuals died from cardiometabolic causes in 2012, including 506,100 individuals from heart disease, 128,294 from stroke, and 67,914 from type 2 diabetes. Of these, 318,656 deaths were attributable to suboptimal intakes of the 10 dietary components. In Blacks and Hispanics, a suboptimal diet was associated with 53.1% and 50.0% of the estimated cardiometabolic deaths, respectively.   

Salt in the US diet appears to be the biggest culprit, with estimates suggesting 9.5% of all cardiometabolic deaths were related to high sodium intakes. Following sodium, not eating enough nuts/seeds, eating too much processed meat, and not eating enough seafood omega-3 fatty acids were dietary factors most associated with cardiometabolic mortality.

For men, too much processed meat, sodium, sugar-sweetened beverages and not enough nuts/seeds and omega-3 fatty acids were the biggest factors associated with cardiometabolic deaths. In women, excess sodium, and not enough nuts/seeds, vegetables, fruits, and omega-3 fatty acids were the top five dietary factors linked with death.

While Congress is actively debating on how to improve health and reduce costs, fixing our food system is among the most essential priorities, a win-win for all. Dariush Mozaffarian

Additionally, the researchers observed some trends over time, with noted improvements in the national intake of polyunsaturated fats, nut/seeds, whole grains, and fruits, and less consumption of sugar-sweetened drinks from 2002 to 2012. The estimated number of deaths attributable to suboptimal intake of polyunsaturated fats, nuts/seeds, and sugary drinks decreased over time and remained relatively stable for whole grains, fruits, vegetables, omega-3 fatty acids, and processed meat. Deaths linked with excessive sodium increased over time, however.   

To TCTMD, the researchers say there are important policy considerations, with their data providing evidence to support health interventions to improve the way Americans eat.

“For example, our research identifies salt as a key target,” said Micha. “The US Food and Drug Administration has recently announced voluntary sodium reduction targets for the food industry. This is quite timely and we need to engage industry to gradually reduce salt content in processed foods. Preventing premature deaths through promoting healthy eating habits is a timely and urgent priority from a health perspective.”

Dietary Studies Carry Inherent Limitations

In an editorial, Noel Mueller, PhD, and Lawrence Appel, MD (Johns Hopkins Bloomberg School of Public Health, Baltimore, MD) agree that the new analysis is relevant to public health nutrition policy, but add the results should be interpreted cautiously given the nature of nutrition research.

For one, the study assumes that the “exposure-outcome” is causal but for diet, “strong evidence from large-scale, long-term randomized trials with hard clinical outcomes is rarely available.” Relying on observational studies—even though the researchers performed multivariate adjustments—is tricky because of the potential for confounding biases.

Additionally, Mueller and Appel note that in such dietary analyses, “decisions about which and how many factors to include are critical,” pointing out that saturated fat, trans fat, sugar, and potassium were not included even though arguments could be made as to their importance in the optimal US diet. An accurate estimation of the effect size of the individual dietary factors is also critical, they note.

Regardless of the limitations—whether the researchers overestimated or underestimated the potential effects of an improved diet—Mueller and Appel state that the likely benefits are substantial and justify policies designed to improve diet quality.

For her part, Micha agrees: “Eating healthy is key, and if we remember that simple fact, most of us can have healthier and better lives,” she said.