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Revision of the New Dietary Reference Intake for Cholesterol Needed?
practice applications
LETTERS TO THE EDITOR
Revision of the New Dietary Reference Intake for Cholesterol Needed? To the Editor: In 2002 the Dietary Reference Intakes (DRIs) for macronutrients, representing the reference values for nutrient intakes by Americans and Canadians, were published (1). However, for three nutrients often linked to cardiovascular diseases (ie, saturated and trans-fatty acids and cholesterol), no intake values are given. Instead, it is recommended that the “consumption be as low as possible.” While the recommendation to minimize the consumption of saturated and trans-fatty acids concurs with dietary recommendations of other organizations, the recommendation to consume as little cholesterol as possible is quite unique to the DRIs. For example, the American Heart Association allows a dietary cholesterol intake up to 300 mg/day. The American Heart Association’s guideline reflects the results of several meta-analyses in which a small increase in total blood cholesterol of 0.05 to 0.06 mmol/L was associated with an increase in dietary cholesterol of 100 mg/day (2-4). For comparison, the increase in total blood cholesterol associated with drinking 600 mL filtered coffee (about 4 cups) per day is 0.15 to 0.25 mmol/L (5). An increase in total blood cholesterol of 0.05 to 0.06 mmol/L is associated with only a small increase in relative risk for total mortality. According to Gould and colleagues (6), “for every 10 percentage points of cholesterol lowering, coronary heart diseases mortality risk would be reduced by 15%, and total mortality risk would be reduced by 11%.” A reduction of 100 mg/day in dietary cholesterol leading to a reduction of 0.05 to 0.06 mmol/L in total blood cholesterol would, therefore, reduce total mortality risk by about 1% (assuming a high total blood cholesterol level of 6.0 mmol/L). It is somewhat surprising that the DRI report recommends consuming as little dietary cholesterol as
362
possible “because any incremental increase in cholesterol intake increases coronary heart disease risk” (1). This recommendation might be the result of a simple misquoting from two papers with predictive equations on blood cholesterol. One meta-analysis (4) was quoted to predict a 0.57 mmol/L increase of blood cholesterol for 100 mg/day dietary cholesterol. In fact, the original statement is “1 [mg/ day] of dietary cholesterol will produce a change in total cholesterol by 0.57 [mol/L].” Therefore, 100 mg would result in 57 mol/L or 0.057 mmol/L and not 0.57 mmol/L. In the second misquoted study (2), 100 mg/ day was said to be associated with an increase of 0.64 mmol/L. However, the original statement is “avoiding 200 [mg/day] dietary cholesterol further decreased blood total cholesterol by 0.13 [mmol/L].” Thus, 100 mg avoidance should be associated with half of 0.13, which is 0.065, and not 0.64. Interestingly, a small increase of 0.065 mmol/L for every 100-mg increase in dietary cholesterol is exactly the median of the 117 single studies tabled in the DRI report. In light of this small influence of dietary cholesterol on total blood cholesterol, the 2002 DRI recommendation does not seem to be appropriate. Since the submission of this letter, the misquoting of the two papers has been corrected in the printed and online 2005 version of the DRIs. However, in spite of this correction, the recommendation to consume as little dietary cholesterol as possible has not been changed. Paolo C. Colombani, Dr Sc Nat Swiss Federal Institute of Technology Zurich Department of Agricultural and Food Sciences Zurich, Switzerland References 1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academy Press; 2002.
Journal of the AMERICAN DIETETIC ASSOCIATION
2. Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: Quantitative meta-analysis of metabolic ward studies. BMJ. 1997;314:112117. 3. Weggemans RM, Zock PL, Katan MB. Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans: A metaanalysis. Am J Clin Nutr. 2001;73: 885-891. 4. Howell WH, McNamara DJ, Tosca MA, Smith BT, Gaines JA. Plasma lipid and lipoprotein responses to dietary fat and cholesterol: A meta-analysis. Am J Clin Nutr. 1997;65:1747-1764. 5. Strandhagen E, Thelle DS. Filtered coffee raises serum cholesterol: Results from a controlled study. Eur J Clin Nutr. 2003;57: 1164-1168. 6. Gould AL, Rossouw JE, Santanello NC, Heyse JF, Furberg CD. Cholesterol reduction yields clinical benefit: Impact of statin trials. Circulation. 1998;97:946-952. doi: 10.1016/j.jada.2006.01.029 Response: Dr Colombani has correctly summarized the evidence base that dietary cholesterol has modest effects on low-density lipoprotein (LDL) cholesterol levels and associated risk of cardiovascular disease (CVD). As noted in the 2002 Dietary Reference Intakes report for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (1), there is much evidence to indicate a positive linear trend between cholesterol intake and LDL cholesterol concentration, and therefore increased risk of coronary heart disease. Based on the evidence, a 100-mg/day increase in dietary cholesterol is expected to increase serum cholesterol about 0.06 mmol/L (2 to 3 mg/dL). Likewise, as would be expected, decreasing just dietary cholesterol reduces LDL cholesterol modestly. This is captured in the third Adult Treatment Panel (ATP III) of the National Cholesterol Education Program. Specifically, reducing dietary cholesterol
© 2006 by the American Dietetic Association
LETTERS TO THE EDITOR
Revision of the New Dietary Reference Intake for Cholesterol Needed? To the Editor: In 2002 the Dietary Reference Intakes (DRIs) for macronutrients, representing the reference values for nutrient intakes by Americans and Canadians, were published (1). However, for three nutrients often linked to cardiovascular diseases (ie, saturated and trans-fatty acids and cholesterol), no intake values are given. Instead, it is recommended that the “consumption be as low as possible.” While the recommendation to minimize the consumption of saturated and trans-fatty acids concurs with dietary recommendations of other organizations, the recommendation to consume as little cholesterol as possible is quite unique to the DRIs. For example, the American Heart Association allows a dietary cholesterol intake up to 300 mg/day. The American Heart Association’s guideline reflects the results of several meta-analyses in which a small increase in total blood cholesterol of 0.05 to 0.06 mmol/L was associated with an increase in dietary cholesterol of 100 mg/day (2-4). For comparison, the increase in total blood cholesterol associated with drinking 600 mL filtered coffee (about 4 cups) per day is 0.15 to 0.25 mmol/L (5). An increase in total blood cholesterol of 0.05 to 0.06 mmol/L is associated with only a small increase in relative risk for total mortality. According to Gould and colleagues (6), “for every 10 percentage points of cholesterol lowering, coronary heart diseases mortality risk would be reduced by 15%, and total mortality risk would be reduced by 11%.” A reduction of 100 mg/day in dietary cholesterol leading to a reduction of 0.05 to 0.06 mmol/L in total blood cholesterol would, therefore, reduce total mortality risk by about 1% (assuming a high total blood cholesterol level of 6.0 mmol/L). It is somewhat surprising that the DRI report recommends consuming as little dietary cholesterol as
362
possible “because any incremental increase in cholesterol intake increases coronary heart disease risk” (1). This recommendation might be the result of a simple misquoting from two papers with predictive equations on blood cholesterol. One meta-analysis (4) was quoted to predict a 0.57 mmol/L increase of blood cholesterol for 100 mg/day dietary cholesterol. In fact, the original statement is “1 [mg/ day] of dietary cholesterol will produce a change in total cholesterol by 0.57 [mol/L].” Therefore, 100 mg would result in 57 mol/L or 0.057 mmol/L and not 0.57 mmol/L. In the second misquoted study (2), 100 mg/ day was said to be associated with an increase of 0.64 mmol/L. However, the original statement is “avoiding 200 [mg/day] dietary cholesterol further decreased blood total cholesterol by 0.13 [mmol/L].” Thus, 100 mg avoidance should be associated with half of 0.13, which is 0.065, and not 0.64. Interestingly, a small increase of 0.065 mmol/L for every 100-mg increase in dietary cholesterol is exactly the median of the 117 single studies tabled in the DRI report. In light of this small influence of dietary cholesterol on total blood cholesterol, the 2002 DRI recommendation does not seem to be appropriate. Since the submission of this letter, the misquoting of the two papers has been corrected in the printed and online 2005 version of the DRIs. However, in spite of this correction, the recommendation to consume as little dietary cholesterol as possible has not been changed. Paolo C. Colombani, Dr Sc Nat Swiss Federal Institute of Technology Zurich Department of Agricultural and Food Sciences Zurich, Switzerland References 1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academy Press; 2002.
Journal of the AMERICAN DIETETIC ASSOCIATION
2. Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: Quantitative meta-analysis of metabolic ward studies. BMJ. 1997;314:112117. 3. Weggemans RM, Zock PL, Katan MB. Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans: A metaanalysis. Am J Clin Nutr. 2001;73: 885-891. 4. Howell WH, McNamara DJ, Tosca MA, Smith BT, Gaines JA. Plasma lipid and lipoprotein responses to dietary fat and cholesterol: A meta-analysis. Am J Clin Nutr. 1997;65:1747-1764. 5. Strandhagen E, Thelle DS. Filtered coffee raises serum cholesterol: Results from a controlled study. Eur J Clin Nutr. 2003;57: 1164-1168. 6. Gould AL, Rossouw JE, Santanello NC, Heyse JF, Furberg CD. Cholesterol reduction yields clinical benefit: Impact of statin trials. Circulation. 1998;97:946-952. doi: 10.1016/j.jada.2006.01.029 Response: Dr Colombani has correctly summarized the evidence base that dietary cholesterol has modest effects on low-density lipoprotein (LDL) cholesterol levels and associated risk of cardiovascular disease (CVD). As noted in the 2002 Dietary Reference Intakes report for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (1), there is much evidence to indicate a positive linear trend between cholesterol intake and LDL cholesterol concentration, and therefore increased risk of coronary heart disease. Based on the evidence, a 100-mg/day increase in dietary cholesterol is expected to increase serum cholesterol about 0.06 mmol/L (2 to 3 mg/dL). Likewise, as would be expected, decreasing just dietary cholesterol reduces LDL cholesterol modestly. This is captured in the third Adult Treatment Panel (ATP III) of the National Cholesterol Education Program. Specifically, reducing dietary cholesterol
© 2006 by the American Dietetic Association