Journal of the American College of Nutrition, Vol. 23, No. 90006, 616S-620S (2004)
Published by the American College of Nutrition
The Canadian Experience: Why Canada Decided Against an Upper Limit for Cholesterol
Bruce E. McDonald, PhD
Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, CANADA
Address reprint requests to: Bruce E. McDonald, PhD, Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2. E-mail: bmcdon{at}ms.umanitoba.ca
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ABSTRACT
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Canada, like the United States, held a "consensus conference on cholesterol" in 1988. Although the final report of the consensus panel recommended that total dietary fat not exceed 30 percent and saturated fat not exceed 10 percent of total energy intake, it did not specify an upper limit for dietary cholesterol. Similarly, the 1990, Health Canada publication "Nutrition Recommendations: The Report of the Scientific Review Committee" specified upper limits for total and saturated fat in the diet but did not specify an upper limit for cholesterol. Canada’s Guidelines for Healthy Eating, a companion publication from Health Canada, suggested that Canadians "choose low-fat dairy products, lean meats, and foods prepared with little or no fat" while enjoying "a variety of foods." Many factors contributed to this position but a primary element was the belief that total dietary fat and saturated fat were primary dietary determinants of serum total and low-density lipoprotein (LDL) cholesterol levels, not dietary cholesterol. Hence, Canadian health authorities focused on reducing saturated fat and trans fats in the Canadian diet to help lower blood cholesterol levels rather than focusing on limiting dietary cholesterol. In an effort to allay consumer concern with the premise that blood cholesterol level is linked to dietary cholesterol, organizations such as the Canadian Egg Marketing Agency (CEMA) reminded health professionals, including registered dietitians, family physicians and nutrition educators, of the extensive data showing that there is little relationship between dietary cholesterol intake and cardiovascular mortality. In addition, it was pointed out that for most healthy individuals, endogenous synthesis of cholesterol by the liver adjusts to the level of dietary cholesterol intake. Educating health professionals about the relatively weak association between dietary cholesterol and the relatively strong association between serum cholesterol and saturated fat and trans fats helped keep consumers informed about healthy diets and ways to control blood cholesterol.
Key words: dietary cholesterol, nutrition recommendations, guidelines to healthy eating, saturated fat, trans fatty acids, Canadian Egg Marketing Agency
Key teaching points:
In the past, Canadian public health nutrition guidelines have emphasized setting upper limits for total and saturated fat in the diet, but did not specify an upper limit for dietary cholesterol.
Unlike in the United States, the emphasis in Canadian nutrition guidelines throughout the 1990s to lower blood cholesterol levels was centered on the type of fat in the diet—saturated fat, polyunsaturated fatty acids, monounsaturated fatty acids and trans fatty acids—rather than dietary cholesterol intake.
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Background
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Canada, like the United States, held its own cholesterol consensus conference. The Canadian conference fell in the aftermath of the U.S. consensus conference [1] and the policy statement by the European Atherosclerosis Society [2], both of which recommended restricting dietary cholesterol intake to a mean of 300 mg daily. It also followed the report of the National Cholesterol Education Program Expert Panel [3].
The Canadian conference, which was held in May 1988, featured two days of presentations and discussion. It was attended by a broad cross-section of delegates from throughout the country, including representatives from the public sector (e.g., universities and health agencies), government (federal, provincial and local), and industry (including the various commodity groups). The Expert Panel, which had been named in advance of the Conference, prepared the consensus recommendations that were published later in the year as a supplement to the Canadian Medical Association Journal [4]. The conference was sponsored by the Canadian Atherosclerosis Society, the Canadian Heart Foundation, the Department of National Health and Welfare, and the Heart and Stroke Foundation of Ontario. Other support came primarily from international pharmaceutical companies, several life insurance companies, and sources, such as the Canadian Egg Marketing Agency and Burns Foods, a major meat processing company.
The Conference Organizing Committee, which was separate from the Expert Panel, put together a program that featured 19 presentations co-authored by a slate of 41 national and international scientists and clinicians. In the end, the Expert Panel made 11 recommendations aimed at decreasing the incidence of cardiovascular diseases in Canada. It recommended that government and voluntary agencies develop health promotion programs that address the full range of cardiovascular risk factors. Although a somewhat "motherhood" statement, this recommendation recognized the extensive evidence that cardiovascular diseases are intimately related to lifestyle and environmental factors which can be modified. The recommendations also called for a reduction in total fat and saturated fat intakes by Canadians. In addition, it was recommended that particular individuals, such as those with a family history of CVD or those with hypertension, diabetes or obesity, be given priority in testing for lipid risk factors.
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Recommendations—Canadian Consensus Conference
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The Expert Panel made a specific recommendation with respect to dietary fat intake, namely that it be reduced to 30 percent or less of total energy. It further recommended that the intake of saturated fat, in particular, lauric acid, myristic acid and palmitic acid, be reduced to 10 percent or less of total energy. The Panel further recommended that the Canadian diet include a source of essential fatty acids but that polyunsaturated fatty acids (PUFA) not exceed 10 percent of total energy intake. The recommendations with respect to dietary fat were consistent with the recommendations of the U.S. Consensus Panel and the European Atherosclerosis Society. In addition, the Canadian Panel recommended that 10 to 15 of energy come from protein and the balance, namely 55 to 60 percent of energy, be provided by carbohydrates with an emphasis on dietary fiber.
The major difference between the Canadian and U.S. recommendations was the absence of an upper limit on cholesterol intake in Canada. The only reference to dietary cholesterol in the Canadian report simply stated, "Some patients with hyperlipidemia may require more rigorous low-fat (less than 30%) and low-cholesterol (less than 300 mg/day) diets as part of their diet therapy". Although this statement implied that dietary cholesterol be 300 mg/day or less, there was no official upper limit set by the Canadian Panel, in contrast to the recommendation in the U.S., namely that "All Americans should be advised to adopt a diet that ... reduces daily cholesterol intake to 250 to 300 mg or less." This difference was a significant split in the dietary recommendations by the two Panels. It is of particular note because the Canadian Panel’s dietary guidelines provided the backdrop to Canada’s "Nutrition Recommendations" published in 1990 [5].
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Canada’s Nutrition Recommendations, 1990
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The Scientific Review Committee, which was named to review and recommend on dietary intakes of energy, the macro-nutrients, vitamins and minerals, (Canada’s RNI’s—Recommended Nutrient Intakes—essentially the equivalent of U.S. RDA’s), not only adopted the dietary guidelines of the Expert Panel of the Canadian Consensus Conference on Cholesterol, with respect to fat and cholesterol intakes, but reinforce these recommendations. The Scientific Review Committee specified eight, what it called, "desired characteristics for the Canadian diet." Included in the desired characteristics were the recommendations that the Canadian diet should: include essential nutrients in the amounts recommended by the Committee; and include no more than 30 percent of energy as fat and no more than 10 percent as saturated fat. Other characteristics recommended: a reduction in the sodium content of the Canadian diet; and that the Canadian diet provide energy consistent with the maintenance of body weight within the recommended range.
Although the report of the Scientific Review Committee devoted a specific chapter to "Cholesterol" and the conclusion to this chapter began with the statement "... it is concluded that reducing the cholesterol intake of the population towards 300 mg/day or less would be beneficial in the long-term for the reduction of mortality from coronary heart disease in this country," the Committee did not include a specific recommendation on dietary cholesterol. In fact, elsewhere in the chapter it was acknowledged that "Both dietary saturated fats and cholesterol are capable of increasing plasma cholesterol levels in man but the impact of cholesterol is less impressive and subject to marked individual variability." The Scientific Review Committee simply reiterated the prevailing recommendation, namely that "The Canadian diet should include no more than 30% of energy as fat (33 g/1000 kcal or 39 g/5000 kJ) and no more than 10% as saturated fat (11 g/1000 kcal or 13 g/5000 kJ)." The Executive Summary went on to say "The evidence linking saturated fat intake with elevated blood cholesterol and the risk of heart disease is among the most persuasive of all diet/disease relationships."
With respect to dietary cholesterol, the Executive Summary simply stated "Dietary cholesterol, though not as influential (as dietary fat) in affecting blood cholesterol, is not without importance." However, the next sentence in the summary, reflected the basic position of the Scientific Review Committee, namely that "A reduction in cholesterol intake normally will accompany a reduction in total fat and saturated fat." Thus, Canada did not set an upper limit for dietary cholesterol because it was the general consensus of the Scientific Review Committee that a reduction in the intake of total fat and, in particular, saturated fat would result in the desired decrease in serum cholesterol level. As a result, emphasis in Canada in the early 90’s centered on: i) total fat intake; and ii) saturated fat intake. Furthermore, Canadian scientists, in general, accepted the European studies, which indicated that, at best, trans fatty acids were as bad as saturated fat and they may even be worse [6,7]. Thus, the emphasis in Canada surrounding dietary fat subsequently, also, included a concern with trans fatty acid intakes.
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Canada’s Guideline to Healthy Eating
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Simultaneous with the formation of the Scientific Review Committee, which was charged with the task of reviewing the scientific literature and revising the nutrition recommendations for healthy Canadians over two years of age, Canada established the Communications/Implementation Committee (CIC). The CIC was responsible for implementation strategies and for developing consumer advice that would embody the revised Nutrition Recommendations [5]. The CIC identified a number of disparities between the nutrition recommendations and existing dietary practices across the country, which placed Canadians at risk for diet-related chronic diseases such as heart disease and certain types of cancer. As a result, Canada’s Guidelines for Healthy Eating (Table 1) were developed as the basic message to be communicated to healthy Canadians over the age of two years. The main areas of change embodied in the Guidelines [8] included: reductions in total and saturated fat, sodium, alcohol and caffeine and increases in complex carbohydrate and fiber. Again, no reference was made to dietary cholesterol per se.
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Emphasis on Type of Fat in the Diet
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It is important to point out that, in Canada, the emphasis on total fat intake gradually gave way to an emphasis on the type of fat in the diet. There continued to be an emphasis on saturated fat as a cardiovascular risk factor but there also was an acceptance of the serum cholesterol lowering effect of monounsaturated fatty acids. This position reflected the finding that fats rich in monounsaturated fatty acids (MUFA) were just as effective as those that were rich in polyunsaturated fatty acids (PUFA) in lowering serum cholesterol levels in humans when each was substituted for saturated fat in the diet [9,10]. In fact, a review paper published by the National Institute of Nutrition in 1993 [11] went so far as to suggest that substitution of MUFA for saturated fat might even be superior to the same substitution with PUFA. Citing papers by Sirtori et al. [12] and Wahrburg et al. [13], the review stated "Results of recent studies indicate that MUFA produced a more favorable effect on plasma lipid and lipoprotein patterns than PUFA in subjects on a moderate fat intake." There was also a growing interest in Canada in the importance of omega-3 (n-3) fatty acids in the prevention of cardiovascular diseases. This interest stemmed from the growing literature indicating omega-3 fatty acids may play a special role in cardiovascular disease [14]. The interest in omega-3 fatty acids also was inspired by the fact that Canada’s nutrition recommendations [5] specified minimal daily intakes for both omega-3 and omega-6 fatty acids.
The NIN review [11] also raised the issue of the adverse effect of trans fatty acids. The 1990 Nutrition Recommendations [5] had suggested that the prevailing levels of trans FA in the Canadian diet were not likely to increase the risk of CVD but that the intake should not increase. The NIN review, by contrast, disagreed with this position. The review pointed out that trans fatty acids not only raise LDL-cholesterol but also lower the level of HDL-cholesterol and concluded that "The hypercholesterolemic effect of trans fatty acids can no longer be ignored." An up-date [15] of the earlier NIN review [11] supported the cautionary position on trans fatty acids. The 2000 review [15] declared "Studies reported over the past decade have confirmed the adverse effects of trans fatty acids on risk factors for cardiovascular disease" and went on to suggest that "Ample evidence supports the recommendation that consumers reduce intakes of both saturated fat and trans fatty acid." In fact, the 2000 review was simply repeating what other groups in Canada had been promoting for several years. In contrast to the position in the United States at the time (viz., 1999), the Expert Committee on Fats, Oils and Other Lipids (ECFOL), a committee that reports to the Government of Canada through Agriculture & Agri-Food Canada, had recommended that Canada include trans fatty acids on nutrition labels. This recommendation is especially noteworthy because the ECFOL includes members representing the edible oil processing industry, including margarine and shortening manufacturers. The 2000 NIN review also emphasized that the earlier predictions of the effect of dietary cholesterol on plasma cholesterol [16] were overestimated. This conclusion was based on meta-analyses of the available published data [17,18].
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Countering Impact of U.S. Position on Dietary Cholesterol
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Although Canada did not set an upper limit for dietary cholesterol and there was a strong consensus that reducing total and saturated fat intakes would result in a decrease in serum cholesterol levels in the general population, there was, nonetheless, considerable pressure on eggs and other cholesterol-containing foods. Furthermore, this pressure prevailed even though the focus in Canada throughout the 90’s was on type of fat in the diet not dietary cholesterol. Pressure on cholesterol-rich foods reflected the close association and the free flow of consumer information between Canada and the United States. Commodity groups, such as the Canadian Egg Marketing Agency (CEMA) which manages the distribution and sale of shell eggs in Canada, were concerned with the potential adverse effect the prevailing environment in the late 80’s and early 90’s might have on the consumption of their products. CEMA, for example, reacted to this situation by establishing a nutrition advisory panel "to advise the Agency on strategies to counter potential adverse information on eggs." The panel was formed in 1989, just a year after the Canadian Consensus Conference on Cholesterol. On the recommendation of the nutrition advisory panel, CEMA set about to position itself as a reputable source of nutrition and health information by basing all nutrition claims and consumer information on sound science. The Agency also decided to target its information to health professionals, namely dietitians, nutrition educators, and family practitioners, as a way of getting its message to the consumer. Commodity groups that were successful with counter campaigns avoided a confrontational stance on dietary cholesterol. They recognized that one of the major challenges, at the time, was the confusion over the legitimate concern with high serum cholesterol levels, and the possible need for some individuals to limit dietary cholesterol intake, and the relatively small effect dietary cholesterol has on this parameter for the majority of the population. These groups also recognized that one way to put dietary cholesterol in perspective was to emphasize the other risk factors associated with cardiovascular disease.
An early initiative undertaken by CEMA was the organization, in cooperation with the Department of Nutritional Sciences at the University of Toronto, of a symposium for health professional that dealt with the full range of diet and cardiovascular disease [19]. CEMA also undertook several other initiatives over the next decade. It developed a newsletter ("Nutrition in Your Practice"), aimed at health professionals (dietitians, nutrition educators, family physicians and public health nurses), that focused on evolving health and nutrition issues. In addition, the Agency co-sponsored "National Nutrition Month" which the Dietitians of Canada plan, organize and coordinate annually, provided grants to organizations such as NIN for special publications, or for activities deemed noteworthy, and developed pamphlets and other materials in cooperation with groups such as Heart and Stroke Canada and the Allergy & Asthma Information Association.
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Conclusion
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It was not an accident or oversight that Canada did not officially adopt an upper limit for dietary cholesterol. The Canadian Consensus Conference recommended specific guidelines for total and saturated fat intake but did not set a specific intake for cholesterol. This position was in stark contrast to the stance taken in the United States. The position by the Expert Committee, which formulated the recommendations that emanated from the Canadian Consensus Conference on Cholesterol, established the backdrop against which Health Canada developed nutrition recommendations for Canada, that were published two years after the Consensus Conference. As in the case of the recommendations from the Consensus Conference, the 1990 Nutrition Recommendations did not recommend an upper limit for cholesterol intake. There was a general belief among nutritionists and health practitioners in Canada that a reduction in total and saturated fat would result in a reduction in dietary cholesterol. As a consequence, emphasis in Canada throughout the 90’s centered on type of fat in the diet—saturated fat, polyunsaturated fatty acids (in particular, omega-3 fatty acids) and trans fatty acids. Nonetheless, there was considerable unease in Canada on the possible adverse effect the free flow of information between the United States and Canada might have on consumer attitudes toward cholesterol-containing foods.
Received June 30, 2004.
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ABSTRACT
Background
