Dietary cholesterol
Dietary cholesterol
London, ON (updated) - The public's attention is beginning to drift away from the anticholesterol message that doctors have been preaching for 40 years, according to the authors of a review in the November 2010 issue of the Canadian Journal of Cardiology.
"A widespread misconception has been developing among the Canadian public and among physicians. It is increasingly believed that consumption of dietary cholesterol and egg yolks is harmless," Dr J David Spence (Robarts Research Institute, London, ON) and colleagues state. The long-standing recommendation to limit dietary cholesterol is still important, especially for people at risk for cardiovascular disease, but a single egg yolk contains approximately 215 mg to 275 mg of cholesterol, more than the 200-mg daily limit recommended by the American Heart Association and National Cholesterol Education Program, and even more than some infamous fast-food items such as KFC's Double Down or Hardee's Monster Thickburger, the authors note.
"We have become increasingly concerned about the pervasive success of egg marketing propaganda," including a brochure touting the benefits of eggs promoted by the Heart and Stroke Foundation [HSF] of Canada, "quoting directly from the egg marketing propaganda," Spence told heartwire. "After I received that, I called the HSF and offered to meet with them to discuss the evidence, but I was brushed off as if I were someone they had never heard of. I am one of very few people to receive continuous peer-reviewed funding from them for over 30 years. . . . It is as if the AHA were brushing off Scott Grundy and Valentin Fuster, in US terms."
The authors criticize two studies that were widely touted by the egg industry as demonstrating that egg consumption did not increase levels of fasting cholesterol. The first study was on weight loss in healthy young people, and "the lack of relevance of an effective weight-loss and exercise program to most patients at risk of vascular disease seemed to escape the commentaries." The second study showed in vitro that eggs contain natural ACE inhibitors, but the findings have "no established relevance to human disease," Spence et al argue.
"Despite widespread belief to the contrary, it is simply not true that dietary cholesterol is harmless," because research over the past 40 years supports reducing dietary cholesterol to reduce LDL levels, which in turn reduces coronary risk, according to the authors. However, they claim, because statins can lower fasting cholesterol by about 10%, many people are not worrying about dietary cholesterol. Statins can lower the risk of coronary artery disease by as much as 40%, but a 1997 study by Hu et al showed that diet may account for as much as 85% of coronary risk.
Epidemiological studies of egg consumption that failed to show a link between eggs and cardiovascular disease in healthy people were not powered to show an effect in healthy people but did show an increased risk of cardiovascular disease with egg consumption among diabetics, the authors point out.
According to Spence, part of the confusion over the importance of dietary cholesterol appears to be over the difference between the fasting cholesterol levels that are tested in patient's blood tests and the nonfasting levels present the other three-quarters of the day. The focus on fasting cholesterol diverts attention from several important risks of dietary cholesterol. Studies have shown that dietary cholesterol increases susceptibility of LDL cholesterol to oxidation, consumption of a lot of cholesterol in a single sitting drastically increases short-term lipemia, and dietary cholesterol potentiates the adverse effects of saturated fat, the so-called "bacon-and-egg effect," the authors argue.
Spence also takes issue with studies of cholesterol in "healthy people." "The only North Americans who are not at risk of stroke or heart attack are those who will die young because of some other cause. Eventually, we all become high risk for vascular events; it's just a matter of time," he said. "By age 45, almost all of us have plaque in the carotid arteries. The rapid progression of carotid plaque area with age is a good reason for virtually all of us to avoid egg yolks, unless we know we have some other fatal illness."
London, ON (updated) - The public's attention is beginning to drift away from the anticholesterol message that doctors have been preaching for 40 years, according to the authors of a review in the November 2010 issue of the Canadian Journal of Cardiology.
"A widespread misconception has been developing among the Canadian public and among physicians. It is increasingly believed that consumption of dietary cholesterol and egg yolks is harmless," Dr J David Spence (Robarts Research Institute, London, ON) and colleagues state. The long-standing recommendation to limit dietary cholesterol is still important, especially for people at risk for cardiovascular disease, but a single egg yolk contains approximately 215 mg to 275 mg of cholesterol, more than the 200-mg daily limit recommended by the American Heart Association and National Cholesterol Education Program, and even more than some infamous fast-food items such as KFC's Double Down or Hardee's Monster Thickburger, the authors note.
"We have become increasingly concerned about the pervasive success of egg marketing propaganda," including a brochure touting the benefits of eggs promoted by the Heart and Stroke Foundation [HSF] of Canada, "quoting directly from the egg marketing propaganda," Spence told heartwire. "After I received that, I called the HSF and offered to meet with them to discuss the evidence, but I was brushed off as if I were someone they had never heard of. I am one of very few people to receive continuous peer-reviewed funding from them for over 30 years. . . . It is as if the AHA were brushing off Scott Grundy and Valentin Fuster, in US terms."
The authors criticize two studies that were widely touted by the egg industry as demonstrating that egg consumption did not increase levels of fasting cholesterol. The first study was on weight loss in healthy young people, and "the lack of relevance of an effective weight-loss and exercise program to most patients at risk of vascular disease seemed to escape the commentaries." The second study showed in vitro that eggs contain natural ACE inhibitors, but the findings have "no established relevance to human disease," Spence et al argue.
"Despite widespread belief to the contrary, it is simply not true that dietary cholesterol is harmless," because research over the past 40 years supports reducing dietary cholesterol to reduce LDL levels, which in turn reduces coronary risk, according to the authors. However, they claim, because statins can lower fasting cholesterol by about 10%, many people are not worrying about dietary cholesterol. Statins can lower the risk of coronary artery disease by as much as 40%, but a 1997 study by Hu et al showed that diet may account for as much as 85% of coronary risk.
Epidemiological studies of egg consumption that failed to show a link between eggs and cardiovascular disease in healthy people were not powered to show an effect in healthy people but did show an increased risk of cardiovascular disease with egg consumption among diabetics, the authors point out.
According to Spence, part of the confusion over the importance of dietary cholesterol appears to be over the difference between the fasting cholesterol levels that are tested in patient's blood tests and the nonfasting levels present the other three-quarters of the day. The focus on fasting cholesterol diverts attention from several important risks of dietary cholesterol. Studies have shown that dietary cholesterol increases susceptibility of LDL cholesterol to oxidation, consumption of a lot of cholesterol in a single sitting drastically increases short-term lipemia, and dietary cholesterol potentiates the adverse effects of saturated fat, the so-called "bacon-and-egg effect," the authors argue.
Spence also takes issue with studies of cholesterol in "healthy people." "The only North Americans who are not at risk of stroke or heart attack are those who will die young because of some other cause. Eventually, we all become high risk for vascular events; it's just a matter of time," he said. "By age 45, almost all of us have plaque in the carotid arteries. The rapid progression of carotid plaque area with age is a good reason for virtually all of us to avoid egg yolks, unless we know we have some other fatal illness."
| Spence and coauthor Dr Jean Davignon (Institut de recherches cliniques de Montreal, QC) report honoraria and speaking fees from several manufacturers of lipid-lowering drugs. Davignon has received support for an annual symposium from Pfizer Canada, and his research has been funded by Pfizer Canada, AstraZeneca Canada, and Merck Frosst Canada. |
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