Travis’ Note: Today’s post comes from Sharona Abramovitch. You can learn more about Sharona at the bottom of this post. The paper that she discusses in this post is available for free via the Applied Physiology, Nutrition and Metabolism website. You can learn how to submit your own guest post here.
Canada’s Food Guide (CFG) was first developed during the post-war era as a tool to guide food rationing, help prevent nutritional deficiencies and improve the health of Canadians (Health Canada2007a; Health Canada, 2005b). It provides basic education on the importance of eating healthy and translates the science of nutrient requirements into more easily understandable recommendations for the public (Health Canada, 2005b). Many of the food guide’s basic messages guiding food selection, such as having a balanced diet, and promoting health have stayed the same over the years; however, guidance on the quantity of food, nutritional messages and approach have evolved over time. For example, the previous 1992 food guide recommended Canadians of all ages consume 5 to 12 servings of grain products; while the current 2007 food guide suggests those between the ages of 19 to 50 consume 6 to 7 servings or 8 servings of grain products depending on gender (HealthCanada, 2007b; HealthCanada, 2007c).
Although the reference number of servings recommended has changed, the size of a serving has remained relatively constant from the 1977 to 2007 CFG (Health Canada, 2007b; Health Canada, 2007d). For example, one serving size equated to one slice of bread in the 1977 guide and one slice of bread would still be considered one serving in the 2007 Food Guide. This is worrisome as the portion sizes of food, including bread, that are available in the grocery store have increased since the 1970s which makes it more difficult for Canadians to accurately determine the amount of food that is equal to one serving size and the total number of servings that they consumed in one day.
In addition, the Canadian population (especially in urban areas like Toronto) has become very ethnically diverse with Whites, South Asians, East Asians and Blacks making up the largest ethnic groups in Canada (Statistics Canada, 2010). The present 2007 Food Guide has included more examples of ethnic specific food items on the food guide, however; it is unknown how Canadians from different ethnic groups interpret a serving size (HealthCanada, 2007c). It has been shown that the term “serving” is often interpreted differently by various ethnic groups and it may translate to “portion” in several languages (Paisley et al., 2005).
The purpose of the present study was:
1) To determine if one serving size and the number of servings consumed can be estimated accurately
2) To determine if there are differences in conceptualizing one serving size and the number of servings consumed between ethnicities
What we did:
A total of 145 men and women from Toronto that self-identified themselves as White, Black, East Asian and South Asian were included in this study.
Participants were asked to portion out the amount of food that they thought was equal to one serving size and then the study investigators measured the amount and compared it to the correct serving for each food item in CFG to determine accuracy. The food items used represent foods from the four food groups and some ethnic food choices such as rice and tofu. Participants were also asked to estimate how much of these foods they would regularly consume at one meal or at one sitting and how frequently they consumed these foods.
A 24-hour dietary recall was collected by a study investigator. Then, the participants were asked to determine the total number of servings that they consumed in a day using their 24-hour recall. Study investigators determined the actual number of servings that were consumed using the food recall. Participants also compared the number of servings they consumed in one day to CFG’s Food Guide recommendations and were asked if and how they could realistically modify their diet to meet CFG recommendations.
What we found:
As shown in Figure 1, when determining accuracy of serving sizes, it was found on average that participants estimated one serving of:
- Fruit, lettuce and grains to be larger than the actual size
- Cheese and meat alternatives to be smaller than the actual size
- Carrots, milk and meat were accurately estimated
Ethnic differences in serving size estimation were related to differences in eating habits. For example, a serving of tofu was significantly underestimated by Whites, South Asians and Blacks by 50% of an actual serving while East Asians were better able to identify an actual serving size of tofu. This may be related to normal higher consumption of tofu by East Asians as compared to other ethnicities.
Using participant’s food records, it was determined that all ethnic groups estimated incorrectly the number of servings that they consumed from the four food groups even after being given the food guide (p <0.05).
On average the number of servings of:
- Fruits and vegetables were underestimated by 1.0 serving
- Grain products were underestimated by 2.1 servings
- Meat and alternatives were underestimated by 0.4 servings
- Milk and alternatives were overestimated by 0.3 servings
Under or over estimating intake may lead people believe that they should add or remove food from their diet to meet recommendations when in reality they may not need to.
After asking participants what they would need to do to meet recommendations such as adding or removing food from their diet
- 68% of participants believed they needed to increase their food intake by >200 calories to meet recommendations
- 9% believed they needed no modifications
On average, participants from all ethnic groups believed that they needed to increase their intake by 250 to 500 calories to meet CFG recommendations.
- For example, participants may add to their diet:
- two cups of 1% milk or 1 cup of grains (~200 calories)
- 1 medium banana or 75 g of chicken (~100 calories)
Approximately 72% of people said they would actually add these more healthy food choices to their diet but did not suggest if they would remove any unhealthy choices to make room for these added foods.
Canadians of all ethnicities are estimating serving sizes inaccurately. Participants often estimated the size of a serving to be larger than what is defined in CFG and estimated that they ate less number of servings than they actually consumed. This resulted in participants inaccurately perceiving that they need to increase food consumption to meet CFG recommendations.
Where we go from there:
Current findings suggest that simply providing individuals with CFG in its current form may not be helpful since servings are not well understood. Some researchers have suggested that larger and more culturally appropriate serving sizes should be used to help improve people’s accuracy in quantifying the amount of food consumed (Paisley et al. 2005; Teufel. 1997; Harnack et al. 2004). If the food guide continues to be used in its current form, more public health initiatives are needed to help educate Canadians on serving sizes. (Adapted from Abramovitch et al., APNM, 2012)
Other methods are often used to educate Canadians about nutrition which may be easier for Canadians to relate to such as the Diabetes Plate Method. This tool provides Canadians with information about what food items to include at a meal and what their plate should look like. However, it still may be hard for Canadians to gauge if their portion is too large or small of the different food items on their plate. More research is needed to determine an appropriate method to help guide food intake and user-friendly tools are needed to aid people in determining appropriate portion sizes when at home and eating out.
About the Author:
Sharona Abramovitch is a registered dietitian in Toronto who has completed her Master of Science degree with Dr. Jennifer Kuk at York University.
Abramovitch SL, Reddigan JI, Hamadeh MJ, Jamnik VK, Rowan CP, Kuk JL. 2012. Underestimating a serving size may lead to increased food consumption when using Canada’s Food Guide. Appl Physiol Nutr Metab. Oct;37(5):923-30. doi: 10.1139/h2012-071. Available here.
Harnack, L., Steffen, L., Arnett, D.K., Gao, S., and Luepker, R.V. 2004. Accuracy of estimation of large food portions. J. Am. Diet. Assoc. 104(5): 804–806. doi:10.1016/j.jada.2004.02.026. PMID:15127068.
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Statistics Canada. 2010b. Canada’s Ethnocultural Mosaic, 2006 Census: Highlights [Online.] Available from www12.statcan.gc.ca/census-recensement/2006/as-sa/97-562/p1-eng.cfm. [Accessed 11 October 2010.]
Teufel, N.I. 1997. Development of culturally competent food frequency questionnaires. Am. J. Clin. Nutr. 65(4 Suppl.):1173S–1178S. PMID:9094917.
Young, L.R., and Nestle, M. 2002. The contribution of expanding portion sizes to the US obesity epidemic. Am. J. Public Health, 92(2): 246–249. doi:10.2105/AJPH.92.2.246. PMID:11818300.
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