Summary of Evidence Base for Guiding Principles and Recommendations
Health Canada carried out its first Evidence Review Cycle for Dietary Guidance between 2013 and 2015, which is referred to as the ‘2015 Evidence Review’. This review looked at evidence from 2006 to 2015. Data gathering methods and findings are presented in detail elsewhere.[1]
Sources of evidence included:
Building on the 2015 Evidence Review, Health Canada continues to monitor the most recent evidence on food and health. Scientific reports that included extensive systematic reviews of the literature on food related topics were considered. High-quality, peer reviewed systematic reviews were also included. Strict inclusion criteria for selecting reports were set. For example, reports had to be published by a leading scientific organization or governmental agency and had to provide the grading of evidence. Exclusion criteria were also defined. For example, industry commissioned reports were excluded.
Evidence supporting Guiding Principle 1:
Dietary patterns
- Association between increased intakes according to the Dietary Approaches to Stop Hypertension (DASH) pattern and decreased blood pressure or LDL cholesterol [2]
- Association between increased intakes according to Mediterranean-style, Portfolio or DASH patterns and decreased LDL cholesterol or cardiovascular disease risk [3]
Foods containing dietary fibre
- Association between increased intakes of foods containing dietary fibre and decreased risk of colorectal cancer [4]
Fruit and vegetables
• Association between increased intakes of fruit and vegetables and decreased cardiovascular disease risk [5]
Nuts
- Association between a diet high in nuts and decreased LDL cholesterol [6]
Soy protein
- Association between increased intakes of soy protein and decreased LDL cholesterol [7]
Red meat (beef, pork, lamb and goat)
- Association between increased intakes of red meat (beef, pork, lamb and goat) and increased risk of colorectal cancer [8]
Saturated fatty acid replacement
- Association between replacement of saturated fatty acids with unsaturated fatty acids and decreased LDL cholesterol or cardiovascular disease risk [9]
Evidence supporting Guiding Principle 2:
Sodium
- Association between increased intakes of sodium and increased blood pressure [10]
Sugars
- Association between increased intakes of added sugar (from food and/or sugar-sweetened beverages) and increased risk of obesity or type 2 diabetes [11]
- Association between increased intakes of sugar-sweetened beverages and increased risk of obesity among children [12]
- Association between increased intakes of sugar-containing beverages and increased risk of dental caries in children [13]
Saturated fatty acid replacement
- Association between replacement of saturated fatty acids with unsaturated fatty acids and decreased LDL blood cholesterol and cardiovascular disease risk [14]
Processed meat
- Association between increased intakes of processed meat (meats processed by smoking, curing or salting, or addition of chemical preservatives) and increased risk of colorectal cancer [15]
Evidence supporting Guiding Principle 3
Health Canada recognizes that knowledge and skills are needed to apply Guiding Principles 1 and 2 and subsequently improve diet quality and health outcomes. The evidence for Guiding principle 3 is primarily drawn from Health Canada’s analysis of the evidence and describes the Canadian context and the settings in which skills can be learned at any stage of life.[16]
Home food preparation and health
- The research on the relationship between home food preparation and health is limited; however, available evidence suggests that home food preparation may be associated with diets that are consistent with healthy eating recommendations.[17]
Canadian context
- There has been a shift from cooking from scratch towards use of pre-prepared, packaged and convenience foods, which require fewer or different skills.[18]
- Canadian households have significantly increased the proportion of the food budget that is spent on ready-to-eat or ready-to-heat convenience foods.[19]
- On average, Canadian households spend about 30 percent of their food budget on meals and snacks purchased from restaurants, cafeterias, vending machines and other ‘away from home’ sources.[20] Meals eaten away from home can increase the amount of calories, sodium, sugars and saturated fat in the diet.[21]
[1] Colapinto CK, Ellis A, Faloon-Drew K, et al. Developing an Evidence Review Cycle model for Canadian dietary guidance. Journal of Nutrition Education and Behavior. 2016;48(1):77-83. Health Canada. Evidence review of dietary guidance: Technical report. Ottawa, 2016.
[2] American College of Cardiology/American Heart Association 2013: Guideline on lifestyle management to reduce cardiovascular risk: a report of the ACC/AHA task force on practice guidelines; Dietary Guidelines Advisory Committee 2015: Scientific report of the DGAC: Advisory report to the Secretary of Health and Human Services and the Secretary of Agriculture.
[3] American College of Cardiology/American Heart Association 2013: Guideline on lifestyle management to reduce cardiovascular risk: a report of the ACC/AHA task force on practice guidelines; Canadian Cardiovascular Society 2016: Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult.
[4] World Cancer Research Fund 2011: CUP report: colorectal cancer; Public Health England Scientific Advisory Committee on Nutrition 2015: Carbohydrates and Health Report.
[5] Health Canada 2015: Summary of Assessment of a Health Claim about Vegetables and Fruit and Heart Disease.
[6] Canadian Cardiovascular Society 2016: Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult.
[7] Health Canada 2015: Summary of Assessment of a Health Claim about Soy Protein and Cholesterol Lowering; Canadian Cardiovascular Society 2016: Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult.
[8] World Cancer Research Fund 2011: CUP report: colorectal cancer.
[9] Health Canada 2012: Summary of Assessment of a Health Claim about the Replacement of Saturated Fat with Mono- and Polyunsaturated Fat and Blood Cholesterol; Dietary Guidelines Advisory Committee 2015: Scientific report of the DGAC: Advisory report to the Secretary of Health and Human Services and the Secretary of Agriculture; Dietary Guidelines Advisory Committee 2010: Report of the DGAC on the Dietary Guidelines for Americans; World Health Organization. 2016: Effect of trans-fatty acid intake on blood lipids and lipoproteins: a systematic review and meta-regression analysis; World Health Organization 2016: Effects of saturated fatty acids on serum lipids and lipoproteins: a systematic review and regression analysis.
[10] World Health Organization 2012: Guideline: sodium intake for adults and children; American College of Cardiology/American Heart Association 2013: Guideline on lifestyle management to reduce cardiovascular risk: a report of the ACC/AHA task force on practice guidelines; Dietary Guidelines Advisory Committee 2010: Report of the DGAC on the Dietary Guidelines for Americans; National Health and Medical Research Council 2011: A review of the evidence to address targeted questions to inform the revisions of the Australian Dietary Guidelines.
[11] Dietary Guidelines Advisory Committee 2015: Scientific report of the DGAC: Advisory report to the Secretary of Health and Human Services and the Secretary of Agriculture.
[12] Dietary Guidelines Advisory Committee 2010: Report of the DGAC on the Dietary Guidelines for Americans.
[13] Scientific Advisory Committee on Nutrition 2015: Carbohydrates and Health Report.
[14] Health Canada 2012: Summary of Assessment of a Health Claim about the Replacement of Saturated Fat with Mono- and Polyunsaturated Fat and Blood Cholesterol; Dietary Guidelines Advisory Committee 2015: Scientific report of the DGAC: Advisory report to the Secretary of Health and Human Services and the Secretary of Agriculture; Dietary Guidelines Advisory Committee 2010: Report of the DGAC on the Dietary Guidelines for Americans; World Health Organization. 2016: Effect of trans-fatty acid intake on blood lipids and lipoproteins: a systematic review and meta-regression analysis; World Health Organization 2016: Effects of saturated fatty acids on serum lipids and lipoproteins: a systematic review and regression analysis.
[15] World Cancer Research Fund 2011: CUP report: colorectal cancer.
[16] Government of Canada. A Look at Food Skills in Canada. Ottawa, 2015; Government of Canada. Improving Cooking and Food Preparation Skills: A Profile of Promising Practices in Canada and Abroad. Ottawa, 2010.
[17] Mills S, White M, Brown H, et al. 2017. Health and social determinants and outcomes of home cooking: A systematic review of observational studies. Appetite. 111:116-134.
[18] Government of Canada. Improving cooking and preparation skills. A synthesis of the evidence to inform program and policy development. Ottawa, 2010.
[19] Moubarac JC, Batal M, Martins AP, et al. Processed and ultra-processed food products : Consumption trends in Canada from 1938 to 2011. Can J Diet Pract Res. 2014;75(1):15-21.
[20] Statistics Canada. Survey of household spending, detailed food expenditures, Canada, regions and provinces. Table 203-0028. Available at http://www5.statcan.gc.ca/cansim/a05?lang=eng&id=2030028 (accessed 2017 February 12).
[21] Nguyen BT, Powell LM. The impact of restaurant consumption among US adults: Effects on energy and nutrient intakes. Public Health Nutr. 2014;17(11):2445-2452.
