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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.

  • Consumption of Ultra-Processed Foods Trending Down But Still High

    processed junk food french fries cola hamburgerUltra-processed foods (UPFs) are back in the news following the publication of two papers this year, both using dietary 24-hour recall data from the Canadian Community Health Survey (CCHS). One paper compared the intake of UPFs and the nutrition profile of the diet between 2004 and 2015 (sample size of 33,924 for the 2004 survey and 20,080 for the 2015 survey; breastfeeding children excluded) (1). The other paper looked at a cross-section of the 2015 UPF consumption data (sample size of 13,608, aged 19 years or older) with associated health effects (2). 
     
    Sound Familiar? 
    In 2019 the PEN® Team wrote two Trending Topics: 

    The studies reviewed in these past Trending Topics (from the U.K. and France), along with the new Canadian analyses, all have in common an agreement that UPFs have low overall nutritional quality and that the high UPF consumption is of concern. UPFs are often characterized as convenient and hyper-palatable with attractive packaging (1).
     
    How Was ‘Ultra-Processed Foods’ Defined?
    The reported food and drink data by survey participants in both 2005 and 2014 (1,2) was classified into four categories according to NOVA classification, an internationally recognized system of classifying ingredients related to industrial food processing, based on a thesis presented by researchers at Brazil’s University of São Paolo over 10 years ago (3). Category 4, UPF, was the focus of the studies:
     
    1. Unprocessed or minimally processed foods including fresh, frozen or dry fruit, vegetables, nuts, legumes and plain meats and milk
    2. Processed culinary ingredients including sugar, salt, butter and vegetables oils
    3. Processed foods like canned fruits and vegetables, artisanal breads and cheeses 
    4. Ultra-processed foods (UPFs) including industrial breads, reconstituted meat products, commercial and soft drinks, confectionary, commercial baked goods, crackers and other salty snacks, sauces, spreads and salad dressings and fast-food and frozen dishes.
     
    What Did the CCHS Analyses Find?
    The good news is that some UPF types, particularly beverages, declined between 2004 and 2015 (1). That said, the overall share of UPFs (including soft drinks) in Canada remained high in 2015 and contributed 46% of total daily energy for the overall population (as compared to 48% in 2004) with the highest for children and adolescents at 50% in 2015 (1,2). The high levels of UPF intake estimated in this study (1) are in line with previously reported estimates based on population-representative nutrition data from Canada and other high income nations (42% of total energy intake in Australia to about 57% in the United Kingdom) (1). For adults aged 55 or older, the intake of UPFs shifted upwards from about 42% of total usual energy in 2004 to 45% in 2015 (1). High UPF consumption was associated with less formal education, living in rural areas, people born in Canada and with Indigenous identity (2).
     
    The researchers estimated the association between UPF consumption and morbidities (both self-reported) using multivariable logistic regression models on the 2015 data. They found that Canadian adults consuming the highest amounts of UPFs as a proportion of their energy intake had (2):
    • 31% higher odds of obesity 
    • 37% higher odds of diabetes
    • 60% higher odds of high blood pressure, compared to those consuming the least amount. 
    (Note: making conclusions about causal relationships from cross-sectional analyses should be done with caution.)   
     
    What Should Happen Next?
    As practitioners, we should continue to promote national healthy eating guideline recommendations to limit the consumption of highly processed foods and drinks. Repeat analysis of UPF intake over time could also help to inform polices targeting the food environment, such as access to UPFs in publicly funded spaces, labelling and taxation initiatives to guide consumer choice. These analyses can also be used to target public health consumer messaging and media literacy components within nutrition-related programs. Continued research on the associations between UPF intake and risk of morbidities is also needed to better understand whether these relationships are causal and if so how health related behaviours could be modified. 

    See Additional Content:
     
    References
    1. Polsky JY, Moubarac JC, Garriguet D. Consumption of ultra-processed foods in Canada. Health Rep. 2020 Nov 18;31(11):3-15. doi: 10.25318/82-003-x202001100001-eng. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/33205938/ 
    2. Nardocci M, Polsky J, Moubarac JC. How ultra-processed foods affect health in Canada. Report prepared for Heart and Stroke. Montréal: TRANSNUT, Department of Nutrition, University of Montreal; June 2019. Available from: https://www.heartandstroke.ca/-/media/pdf-files/canada/media-centre/hs-moubarc-study-june-27-2019.ashx?rev=8ac040d6d03a41209fc6d8353ed325b3&hash=81A02F9268388596BD7089AA9C22419D 
    3. Monteiro CA. Nutrition and health. The issue is not food, nor nutrients, so much as processing. Public Health Nutr. 2009;12(5):729–31. Available from: https://pubmed.ncbi.nlm.nih.gov/19366466/     

    Posted: 2020-11-30

  • Red and Processed Meat – It’s All About Interpretation

    The International Agency for Research on Cancer (IARC) reported in 2015 that high processed meat or red meat diets are associated with higher relative risks of cancer, with stronger negative evidence for processed meats than red meat (1). 

     

    Johnston et al recently published a series of five systematic reviews in Annals of Internal Medicine that recommended that adults continue to consume red meat and processed meat at current levels of intake (2). These researchers considered three servings per week as a realistic reduction in meat consumption. Using meta-analyses to summarize the findings, they interpreted the data in two ways:  they quantified how many per 1000 people would likely benefit from reducing red and processed meat consumption and then used Grading of Recommendations Assessment, Development and Evaluation (GRADE) tools (3,4) to translate these findings into recommendations. 

     

    Who’s Right?

    Both the IARC and Johnston et al recognized limitations of the strengths of the evidence about red and processed meats (1,2).  It was when Johnston et al interpreted their findings and made their recommendations that they differed from IARC’s conclusions. Johnston et al (1) used GRADE tools (4) to translate the findings into absolute risk differences and then make recommendations. GRADE instructs researchers when making recommendations to transparently consider the evidence concerning effects on health, as well as to consider values and preferences, costs, acceptability and feasibility of a recommendation. The GRADE methods have been endorsed by over 100 organizations including the World Health Organization and the Cochrane Collaboration (5). 

     

    Both groups looked at the body of evidence, which is observational study data. Regarding cancer, the IARC reported relative risks and statistical significance.

    “Positive associations of colorectal cancer with consumption of processed meat were reported in 12 of the 18 cohort studies that provided relevant data, including studies in Europe, Japan, and the USA. Supporting evidence came from six of nine informative case-control studies. A meta-analysis of colorectal cancer in ten cohort studies reported a statistically significant dose–response relationship, with a 17% increased risk (95% CI 1•05–1•31) per 100 g per day of red meat and an 18% increase (95% CI 1•10–1•28) per 50 g per day of processed meat” (1). 

     

    Johnston et al translated their summary of the evidence into absolute risks of having a cardiometabolic or cancer outcome event:

    “Although statistically significant, low- to very low-certainty evidence indicates that adherence to dietary patterns lower in red or processed meat is associated with a very small absolute risk reduction in 9 major cardiometabolic and cancer outcomes (range, 1 fewer to 18 fewer events per 1000 persons), with no statistically significant differences for 21 additional outcomes observed” (2).

     

    The Johnston et al (2) group were divided when they voted about their recommendations to “continue current levels of red meat and processed meat consumption” (11 voted for the recommendation, three voted against it). They considered the following data for their recommendation:

    • the low to very low certainty of evidence for the potential adverse health outcomes 
    • the very small absolute risk reduction based on three fewer servings of red or processed meat per week
    • the small risk reductions combined with “peoples' attachment to their meat-based diet”, “is not likely to provide sufficient motivation to reduce consumption of red meat or processed meat” 
    • the large variability in peoples' values and preferences related to meat, and
    • the panel focused exclusively on health outcomes associated with meat and did not consider animal welfare and environmental issues.  

    There is strong criticism of Johnson et al's paper. As an example, a press release from the Harvard T.H. Chan School of Public Health described the Johnston et al publication as “irresponsible and unethical to issue dietary guidelines that are tantamount to promoting meat consumption” (6).

     

    Interpreting the Evidence

    GRADE recommends looking beyond statistical significance to examine several quality of research indicators and the actual numerical strength of the effects. (See PEN® eNews article - Why Using GRADE (to grade the evidence in PEN®) is Important to Practicing Dietitians). The GRADE tools are intended to be used to evaluate the body of evidence about any health interventions for its strength, consistency, directness and precision for improving health and the individual studies for the risks of bias. (Refer to PEN® eNews article, How PEN is ‘GRADE’ing the Evidence for You for reasons why PEN is using GRADE methods). Essentially, both those who recommend continued meat consumption (2) and those who recommend decreased meat consumption (1,5) have made subjective assessments to judge the evidence and make their recommendations. Being transparent based on the GRADE methods, the new analysis (2) may be more substantiated, but as before, the evidence is not strong and decisions about eating or not eating meat comes down to individual preferences.

    Many nutrition science recommendations are based on observational studies of what people eat and their subsequent health outcomes. A weakness of this approach is that people who eat healthy diets usually have higher incomes, do not smoke and practice other healthy lifestyles including more physical activity and a moderate alcohol intake. It is challenging, if not impossible, to disentangle these effects to be able to say that a healthy diet is the reason for better health outcomes. 


    Bottom Line
    There is no strong evidence to definitively support either the recommendations for continued red and processed meat consumption (2) or decreased meat consumption (1). The new analysis by Johnston et al (2) is based on the latest and endorsed methods (5) to summarize essentially the same evidence and to make recommendations. By using recommended methods, the new report (2) may be more substantiated. However, individual preferences and choices about eating meat are key to how we as dietitians work with clients. 

    The weaker the evidence, the more dietitians’ knowledge and professional training matter to interpret and to provide nutrition guidance. We need to continue to respect people’s values and preferences as well as to encourage a variety of foods in moderation and to make wise and informed choices to meet nutrition needs. Those who avoid or decrease their meat consumption for health, environmental and/or animal welfare reasons may need assistance obtaining sufficient protein, iron, zinc and vitamin B12. Those who avoid dairy products, may need assistance obtaining sufficient protein and calcium, especially children (7). People who eat generous quantities of meat may need assistance to ensure their diet contains sufficient vegetables, fruit, calcium and fibre.


    Most diets would likely be improved with the inclusion of some plant-based proteins including some beans, lentils and nuts for their fibre, low glycemic index and nutrient contributions. Recommended nutrient intakes for protein (8) and current country dietary guidelines should continue to be followed. See Additional Content: International Healthy Eating Guideline Collection.

     

    References

    1. Bouvard V, Loomis D, Guyton KZ, Grosse Y, Chissassi FE, Benbrahim-Tallaa L, et al. Carcinogenicity of consumption of red and processed meat. Lancet Oncol. 2015  Dec;16(16):1599-600. Abstract available from:  https://www.ncbi.nlm.nih.gov/pubmed/26514947
    2.  Johnston BC, Zeraatkar D, Han MA, Vernooij RWN, Dib EL, Marshall C, et al. Unprocessed red meat and processed meat consumption: dietary guideline recommendations (NutriRECS) Consortium. Ann Intern Med. 2019 Oct. doi:10 .7326/M19-1621. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/31569235
    3.  Guyatt GH, Oxman AD, Akl EA, Kunz R, Vist G, Brozek J, et al. GRADE guideline: 1. Introduction – GRADE evidence profiles and summary of findings tables. J Clin Epidemiol. 2011 Apr;64(4):383-94. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/21195583
    4.  Schünemann H, Brożek J, Guyatt G and Andrew Oxman A, Eds. Handbook for grading the quality of evidence and the strength of recommendations using the GRADE approach. 2013. Available from: https://gdt.gradepro.org/app/handbook/handbook.html
    5.  GRADE. GRADE working group. [cited 2019 Oct 2]. Available from: http://www.gradeworkinggroup.org/
    6.  Harvard T.H. Chan School of Public Health. New “guidelines” say continue red meat consumption habits, but recommendations contradict evidence. The Nutrition Source. 2019 Sep 30. Available from:  https://www.hsph.harvard.edu/nutritionsource/2019/09/30/flawed-guidelines-red-processed-meat/

    7. Dietitians of Canada. Plant-based beverages – are they really healthier for young children? Trending Topic. In: Practice-based Evidence in Nutrition [PEN]. 2017 Aug. Available from: https://www.pennutrition.com/resourcestools.aspx?trcatid=496&trid=26285&sr=plant-based Access only by subscription. Click Sign Up on PEN login page.

    8. The National Academies Press. Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. 2005. Available from: https://www.nap.edu/read/10490/chapter/12

    Posted: 2019-10-02

  • Ultra-processed Foods and Early Death

    Researchers continue to explore the relationship between the foods we eat and health outcomes. The British Medical Journal (BMJ) recently published two articles on the health effects associated with the consumption of ultra-processed foods and early death:

    The National Health Service (NHS) in the U.K. has provided this analysis of the research, which notes the challenges of cohort studies, including the inability to prove cause and effect, the importance of potential confounding factors with observational research, and the difficulty of defining ultra-processed foods. People who frequently eat ulta-processed foods are different in several ways including income, physical activity and smoking habits, from people who eat foods prepared from scratch (1); it is not possible in studies such as these to fully control for these differences. Thus, it is cannot be assumed that the ultra-processed foods actually caused the cardiovascular disease or early deaths or that other aspects of their lifestyle were more important. 

    In addition, see the February 2019 PEN Trending Topic: The Association Between Ultraprocessed Food Consumption and the Risk of Mortality – What is the Real Deal?

    References:

    1. Schnabel L, Kesse-Guyot E, Allès B, Touvier M, Srour B, Hercberg S, et al. Association between ultraprocessed food consumption and risk of mortality among middle-aged adults in France. JAMA Intern Med. 2019 Feb 11. doi:10.1001/jamainternmed.2018.7289. [Epub ahead of print]. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/30742202   

    Posted: 2019-06-06

  • The Association Between Ultraprocessed Food Consumption and the Risk of Mortality – What is the Real Deal?

    Originally Posted February 15, 2019. Reposted June 5, 2019 

    Another observational nutrition study is making headlines around the world (1-3) but is also raising concerns about the failure of news stories to address the significant limitations of the study. The observational prospective cohort study looked at the association between ultraprocessed food consumption and the risk of mortality in middle-aged adults in France (4). The authors concluded that an association existed based on the data of more than 44,000 participants. 

    A PEN Evidence Analyst offered this analysis:
    The results portray a very weak relationship between ultraprocessed foods and mortality. The effect size, which was equal to a hazard ratio of 1.14, is so small that it is not likely of importance. GRADE guidelines encourage that for an observational study an effect size should be greater than 2, or better yet 5, before we should assume that there is an important effect (5). This hazard ratio of 1.14 was statistically significant, which is not surprising because there were over 44,000 participants in the study. When the sample size is very large, statistical significance is highly likely even when the effect is so small that it is not likely of any real importance.

    Additional concerns are that the categorization of foods in the ultraprocessed category included sugar-sweetened beverages and highly processed snack foods but also included ready-made meals and breads, which could be quite nutritious. Further, the researchers allowed the participants to select which 24-hour periods they reported their food intake, so we don’t know how well their selections reflect typical intakes.

    The results observed could be due to the fact that those that ate the most of these ultraprocessed foods were those most likely to have higher mortality rates for reasons beyond dietary intake. The individuals consuming the most of these ultraprocessed foods were more likely to be of lower income, smoke and/or be single obese males with low levels of physical activity. Some additional variable or variables related to these variables that were controlled for in the analysis could be the actual causal factor for mortality. Therefore, residual confounding may explain this study’s results.

    The researchers did mention that reverse causation was possible; that is those people who are at higher risk of death from a chronic disease may have been selecting more processed foods. This type of study design cannot rule out reverse causation.

    The NHS and Science Media Centre reviews also outline the limitations and put the study and its findings into perspective.  

    References:

    1. Scutti S. Eating 'ultraprocessed' foods accelerates your risk of early death, study says. CNN. 2019 Feb 12. Available from: https://edition.cnn.com/2019/02/11/health/ultraprocessed-foods-early-death-study/index.html
    2. Eating ultra-processed foods can increase risk of early death: study. CTV. 2019 Feb 12. Available from: https://www.ctvnews.ca/health/eating-ultra-processed-foods-can-increase-risk-of-early-death-study-1.4293071
    3. Donnelly L. Modern diets could be killing us, suggests major study on ultra-processed foods. The Telegraph News. 2019 Feb 11. Available from: https://www.telegraph.co.uk/news/2019/02/11/modern-diets-could-killing-us-suggests-major-study-ultra-processed/
    4. Schnabel L, Kesse-Guyot E, Allès B, Touvier M, Srour B, Hercberg S, et al. Association between ultraprocessed food consumption and risk of mortality among middle-aged adults in France. JAMA Intern Med. 2019 Feb 11. doi:10.1001/jamainternmed.2018.7289. [Epub ahead of print]. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/30742202
    5. Guyatt GH, Oxman AD, Sultan S, Glasziou P, Akl EA, Alonso-Coello P, et al. GRADE guidelines: 9. Rating up the quality of evidence. J Clin Epidemiol. 2011 Dec;64(12):1311-6. doi: 10.1016/j.jclinepi.2011.06.004. Epub 2011 Jul 30. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/?term=21802902

    Posted: 2019-06-05
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