Trending Topics pieces (Article Analyses, Evidence Clips and Other Topics) are published in timely response to recent media and journal articles, position statements, clinical guidelines, etc. Since they are based on the most recent evidence/publications, they may not be consistent with PEN evidence in other PEN content areas. As soon as possible, when this occurs, the PEN content will be reviewed and updated as needed.
Is Diet Associated with Death Rates Across the Globe?
A study published in the Lancet of the global burden of disease tracked consumption trends of 15 dietary factors between 1990 and 2017 in 195 countries. The study looked at major food groups, some nutrients and examined the associations between diet and death and disability-adjusted life-years from non-communicable diseases (e.g. diabetes, cardiovascular disease, cancer). Dietary elements examined included estimated intakes of fruit, vegetables, legumes, whole grains, nuts and seeds, milk, fibre, calcium, seafood omega-3 fatty acids, polyunsaturated fats, red meat, processed meat, sugar-sweetened beverages, trans fatty acids and sodium.
The authors observed that diets low in whole grains and fruit, and high in sodium were associated with more than half of all diet-related global deaths. In North America, the data suggested that the largest dietary contributor to death was from the low intake of whole grains. For more reading about the study and a discussion of some the limitations, see the Science News article Globally, One in Five Deaths are Associated with Poor Diets.
This study is an ecologic study, since the researchers analyzed country-specific data rather than individuals’ data (1,2). They did not know whether the people who died were the people with inferior diets, rather they assumed that the diet information represented everyone in the country (1). The study primarily used dietary intake data prepared by others, usually 24-hour recall data for dietary estimates. There were likely differences in how diets were measured in the various countries. Twenty-four-hour recall data is likely to vary in quality and may not provide strong representations of participants diets (3).
The researchers adjusted the country mortality rates for differences in age and sex distributions in the countries (1). There were no considerations for smoking, physical activity, weight status, other lifestyle variables or inequality in the countries. The analysis assumed that everyone in the countries consumed the average diet of those studied in each country. The results stratified by socioeconomic status (SES), showed weaker relationships between diet and mortality for people with the highest and lowest SES. These findings suggest that other factors, such as social determinants of health, which influence economic conditions, lifestyle, smoking etc., are likely more influential (positively for high SES and negatively for low SES) making diet relatively less influential on mortality at the extremes of SES.
This study has a positive focus on foods that may improve health outcomes. Caution is needed in interpreting this ecologic studies’ results since interpretations could be considered an “ecological fallacy”, especially if these findings are used to assume that the noted association exists for individuals and that if individuals make these dietary changes it would decrease their risk of death (2).
- GBD 2017 Diet Collaborators. Health effects of dietary risks in 195 countries, 1990-2017: a systematic analysis for the Global Burden of Disease study 2017. The Lancet. Published online 2019 Apr 3. Available from DOI: http://dx.doi.org/10.1016/S0140-6736(19)30041-8
- Barratt B, Kirwan M 2009, Shantikumar S 2018. The design, applications, strengths and weaknesses of descriptive studies and ecological studies. HealthKnowledge. Education, CPD and Revalidation from PHAST. 1a-Epidemiology. 2018. [cited 2019 Apr 7]. Available from: https://www.healthknowledge.org.uk/public-health-textbook/research-methods/1a-epidemiology/descriptive-studies-ecological-studies
- Amoutzopoulos B, Steer T, Roberts C, Cade JE, Boushey CJ, Collins CE, et al. Traditional methods v. new technologies – dilemmas for dietary assessment in large-scale nutrition surveys and studies: a report following an international panel discussion at the 9th
International Conference on Diet and Activity Methods (ICDAM9), Brisbane, 3
September 2015. J Nutr Sci. 2018 Apr 2;7e:11.
DOI: 10.1017/jns.2018.4. eCollection 2018. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/?term=29686860
Carbohydrate, Fat and Mortality
Reposted January 3, 2018 with an additional dietitian viewpoint*
The study, Associations of Fat and Carbohydrate Intake with Cardiovascular Disease and Mortality in 18 Countries from Five Continents (PURE): A Prospective Cohort Study, stemming from the PURE macronutrient studies, has been getting a lot of press across the globe (e.g. Canada, U.K.). This is a very large international cohort comprising high, middle and low income countries. It is an observational analysis with dietary intake collected by self-reported food frequency questionnaires (FFG) at baseline only. After looking at a range of carbohydrate (46-77% of energy) and saturated fat (2.8-13.2% of energy) intake (not a typical range seen in North America or Europe) the authors found that high carbohydrate intake was associated with a higher risk of total mortality, and non-cardiovascular disease mortality (e.g. cancer, respiratory diseases).
For analysis on the study, see: NHS Choices - Behind the Headlines
For further analysis on the study, see The Conversation: New Study Finding Fat Isn't as Bad as Carbs Misses the Point
*For a dietitian's viewpoint, see: That Viral Study Telling You to Eat More Fat? It's Full of Holes
For more information, see PEN Additional Content:
Practice Question: Is a Reduced Saturated Fat Diet Recommended for Primary or Secondary Cardiovascular Disease Prevention?
Evidence Clip: Butter, Margarine, Saturated and Trans Fats - Making Sense of Research Reported in the News
Article Analysis: Plant-based Diets and Chronic Disease
Food Insecurity and Chronic Disease
A recent report from the U.S. Department of Agriculture describes the negative impact poor nutrition can have on an adult's health. The report, Food Insecurity, Chronic Disease, and Health Among Working-Age Adults used 2011-2015 data obtained from the National Health Interview Survey (NHIS), a source for national statistics on the health of the U.S. population. The report examined food insecurity as a predictor of health among working adults (41,854 total adults from households; ages 19-64 years) living at or below 200% of the U.S. federal poverty line. The differences in health outcomes (related to 10 chronic diseases) across the range of household food insecurity: high, marginal, low and very low were examined. Food insecurity was found to be significantly associated with all 10 of the chronic diseases studied. Individuals with low and very low food insecurity had higher rates of high blood pressure, heart disease, cancer, asthma, diabetes, arthritis, kidney disease, hepatitis, stroke and chronic obstructive pulmonary disease. These changes in disease prevalence rates by food insecurity status were statistically significant for all of the conditions studied. For all of these diseases, an individual's food insecurity predicted chronic illness rates in a dose-response way. As food security changed from food secure through to highly food insecure, the disease prevalence was higher as food insecurity worsened, with the highest rates for each of these diseases most prevalent among individuals with very low food security.
For country-specific positions see: