Eggs and CHD Risk
A survey conducted by the Egg Nutrition Center found that almost one-quarter of Americans avoid eggs because of concern about dietary cholesterol. The AHA does not specifically mention eggs in its current dietary recommendations to reduce the risk of CHD; however, the NCEP specifically recommends consuming no more than two egg yolks per week and includes egg yolks and whole eggs on a list of “food items to choose less often.”
As already mentioned, one analysis found that for every 100-mg reduction in dietary cholesterol, a 2.2 mg/dL drop in total blood cholesterol would be expected. Using that formula, however, estimates have indicated that the 27% decrease in per-capita egg consumption that took place between 1965 and 1995 would account for only about 3% of the 30 mg/dL fall in the average cholesterol level in the population that also occurred during the same time period. This suggests that restricting egg consumption is unlikely to have a significant effect on blood cholesterol levels or on CHD risk related to elevated cholesterol.
One of the most cited studies on egg consumption and heart health is the Harvard Egg Study, which found that consuming as many as seven eggs per week was not associated with CHD among both men and women.12 The classic Framingham Heart Study, in which male subjects consumed an average of six eggs per week and women consumed an average of four per week, found no association between egg intake and blood cholesterol or CHD incidence. Similarly, a study of Japanese men and women found no clear association between egg consumption and the risk of acute myocardial infarction among subjects consuming four or more eggs per week.13 A study of almost 10,000 men and women observed no significant difference in the risk of coronary artery disease (CAD) between those who consumed more than six eggs per week and those who consumed less than one egg per week over a 20-year follow-up period.
Moreover, at least two studies have found a reduced risk of CHD associated with egg consumption. One Japanese study, published by Sauvaget et al in the International Journal of Epidemiology in 2003, found a 30% lower risk of stroke among a large group of men and women who consumed eggs “almost daily.” When analyzed for the type of stroke, the subjects’ consumption of animal products (including eggs) was negatively associated with intracerebral hemorrhage mortality but was not related to cerebral infarction death. Another study, published by Gramenzi et al in BMJ in 1990, found a 20% lower risk of myocardial infarction among women who consumed more than two eggs per week compared with those who consumed less than one per week. Few studies have found a positive association between egg consumption and CHD. Among 514 Australian Aborigines, consuming more than two eggs per week was associated with a 2.6 times greater risk of CAD in a prospective analysis.15 The Oxford Vegetarian Health Study observed a trend of increasing mortality attributed to ischemic heart disease with increasing egg consumption, but the findings were not significant. While the consumption of six or more eggs per week was associated with a nearly threefold increased risk of CHD death compared with an intake of less than one egg per week, the findings were inconsistent, as those in the middle egg-intake groups had significantly lower death rate ratios than those in the lowest intake category.
Another study that analyzed the relative risk posed by various diet and lifestyle factors determined that for the majority of U.S. adults aged 25 and older, consuming one egg per day accounts for less than 1% of CHD risk. The researchers found that other modifiable risk factors, including smoking, overweight or obesity, poor diet, and inactivity, accounted for about 30% to 40% of the adult population’s CHD mortality. Other factors, such as hypertension, diabetes, genetics, and age, accounted for 60% to 70% of risk. The authors concluded that focusing on decreasing egg intake as an approach to modify CHD risk would likely yield minimal results relative to changing other behaviors, such as quitting smoking.16
Studies indicate that HDL cholesterol levels increase in response to egg consumption, thereby lessening to some extent the effects of egg intake on LDL cholesterol. Research involving subjects on a Step 1 AHA diet who consumed two eggs per day17 and subjects on a carbohydrate-restricted diet that included three eggs per day yielded this result.18
The subfraction of LDL cholesterol that increases with egg consumption may also be an important factor in determining risk. In a group of older men and women assigned to eat either three eggs per day or a cholesterol-free egg substitute, those identified as hyperresponders experienced a significant increase in LDL cholesterol when consuming eggs.19 The study also analyzed for LDL subfractions and found an increase only in the larger LDL particles. These larger, more buoyant LDL particles are believed to be less atherogenic.
There is some evidence, however, of a greater risk posed by egg consumption among subjects with diabetes. The Harvard Egg Study found that men with diabetes who consumed at least one egg per week had a two times greater risk of CAD compared with those who reported an intake of less than one egg per week. Another study, by Qureshi et al, published in 2007 in Medical Science Monitor, found a two times greater risk of CAD among subjects with diabetes who reported an intake of six or more eggs per week compared with those who reported an intake of less than one egg per week.
Egg Nutrition
One large egg provides 75 kcal and 186 mg of cholesterol. Eggs are also a source of 13 essential nutrients, including vitamin B12, iron, vitamin D, zinc, folate, and choline, and they provide high-quality protein (6 g, or 13% of the Daily Value). Eggs have traditionally been used as the standard of comparison for measuring protein quality because of their essential amino acid profile and high digestibility. When evaluated as a percentage of protein content, egg protein provides as many (or more) essential amino acids as any other animal protein.
Eggs are the single most concentrated source of choline in the American diet. Choline intake has been associated with improved levels of biomarkers for cardiovascular health.20 Eggs are also a good source of the carotenoids lutein and zeaxanthin, both important nutrients for eye health. Research suggests that higher intakes of the two carotenoids are associated with a reduced risk of cataracts and macular degeneration. While limiting egg consumption limits a major source of dietary cholesterol, it also limits an economical source of several important nutrients.
Summary
While dietary cholesterol, of which egg yolks are a major source, was once thought to play a primary role in determining plasma cholesterol levels, and therefore CHD risk, scientific opinion appears to be shifting to the belief that it may have a negligible effect in most healthy people.
The relationship between dietary cholesterol and serum cholesterol levels is complex and dependent on a large number of factors, such as dietary fiber, saturated fat, and polyunsaturated fat intake; obesity; insulin resistance; and genetics. Several lifestyle factors, such as smoking, inactivity, and overweight, are clearly associated with an increased CHD risk and also play integral roles.
The evidence overwhelmingly suggests there is no increased risk of CHD with egg consumption for healthy adults. There does, however, appear to be an increased risk of CHD associated with egg consumption for those diagnosed with diabetes.
— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Tex.
http://www.todaysdietitian.com/newarchives/060111p40.shtml
A survey conducted by the Egg Nutrition Center found that almost one-quarter of Americans avoid eggs because of concern about dietary cholesterol. The AHA does not specifically mention eggs in its current dietary recommendations to reduce the risk of CHD; however, the NCEP specifically recommends consuming no more than two egg yolks per week and includes egg yolks and whole eggs on a list of “food items to choose less often.”
As already mentioned, one analysis found that for every 100-mg reduction in dietary cholesterol, a 2.2 mg/dL drop in total blood cholesterol would be expected. Using that formula, however, estimates have indicated that the 27% decrease in per-capita egg consumption that took place between 1965 and 1995 would account for only about 3% of the 30 mg/dL fall in the average cholesterol level in the population that also occurred during the same time period. This suggests that restricting egg consumption is unlikely to have a significant effect on blood cholesterol levels or on CHD risk related to elevated cholesterol.
One of the most cited studies on egg consumption and heart health is the Harvard Egg Study, which found that consuming as many as seven eggs per week was not associated with CHD among both men and women.12 The classic Framingham Heart Study, in which male subjects consumed an average of six eggs per week and women consumed an average of four per week, found no association between egg intake and blood cholesterol or CHD incidence. Similarly, a study of Japanese men and women found no clear association between egg consumption and the risk of acute myocardial infarction among subjects consuming four or more eggs per week.13 A study of almost 10,000 men and women observed no significant difference in the risk of coronary artery disease (CAD) between those who consumed more than six eggs per week and those who consumed less than one egg per week over a 20-year follow-up period.
Moreover, at least two studies have found a reduced risk of CHD associated with egg consumption. One Japanese study, published by Sauvaget et al in the International Journal of Epidemiology in 2003, found a 30% lower risk of stroke among a large group of men and women who consumed eggs “almost daily.” When analyzed for the type of stroke, the subjects’ consumption of animal products (including eggs) was negatively associated with intracerebral hemorrhage mortality but was not related to cerebral infarction death. Another study, published by Gramenzi et al in BMJ in 1990, found a 20% lower risk of myocardial infarction among women who consumed more than two eggs per week compared with those who consumed less than one per week. Few studies have found a positive association between egg consumption and CHD. Among 514 Australian Aborigines, consuming more than two eggs per week was associated with a 2.6 times greater risk of CAD in a prospective analysis.15 The Oxford Vegetarian Health Study observed a trend of increasing mortality attributed to ischemic heart disease with increasing egg consumption, but the findings were not significant. While the consumption of six or more eggs per week was associated with a nearly threefold increased risk of CHD death compared with an intake of less than one egg per week, the findings were inconsistent, as those in the middle egg-intake groups had significantly lower death rate ratios than those in the lowest intake category.
Another study that analyzed the relative risk posed by various diet and lifestyle factors determined that for the majority of U.S. adults aged 25 and older, consuming one egg per day accounts for less than 1% of CHD risk. The researchers found that other modifiable risk factors, including smoking, overweight or obesity, poor diet, and inactivity, accounted for about 30% to 40% of the adult population’s CHD mortality. Other factors, such as hypertension, diabetes, genetics, and age, accounted for 60% to 70% of risk. The authors concluded that focusing on decreasing egg intake as an approach to modify CHD risk would likely yield minimal results relative to changing other behaviors, such as quitting smoking.16
Studies indicate that HDL cholesterol levels increase in response to egg consumption, thereby lessening to some extent the effects of egg intake on LDL cholesterol. Research involving subjects on a Step 1 AHA diet who consumed two eggs per day17 and subjects on a carbohydrate-restricted diet that included three eggs per day yielded this result.18
The subfraction of LDL cholesterol that increases with egg consumption may also be an important factor in determining risk. In a group of older men and women assigned to eat either three eggs per day or a cholesterol-free egg substitute, those identified as hyperresponders experienced a significant increase in LDL cholesterol when consuming eggs.19 The study also analyzed for LDL subfractions and found an increase only in the larger LDL particles. These larger, more buoyant LDL particles are believed to be less atherogenic.
There is some evidence, however, of a greater risk posed by egg consumption among subjects with diabetes. The Harvard Egg Study found that men with diabetes who consumed at least one egg per week had a two times greater risk of CAD compared with those who reported an intake of less than one egg per week. Another study, by Qureshi et al, published in 2007 in Medical Science Monitor, found a two times greater risk of CAD among subjects with diabetes who reported an intake of six or more eggs per week compared with those who reported an intake of less than one egg per week.
Egg Nutrition
One large egg provides 75 kcal and 186 mg of cholesterol. Eggs are also a source of 13 essential nutrients, including vitamin B12, iron, vitamin D, zinc, folate, and choline, and they provide high-quality protein (6 g, or 13% of the Daily Value). Eggs have traditionally been used as the standard of comparison for measuring protein quality because of their essential amino acid profile and high digestibility. When evaluated as a percentage of protein content, egg protein provides as many (or more) essential amino acids as any other animal protein.
Eggs are the single most concentrated source of choline in the American diet. Choline intake has been associated with improved levels of biomarkers for cardiovascular health.20 Eggs are also a good source of the carotenoids lutein and zeaxanthin, both important nutrients for eye health. Research suggests that higher intakes of the two carotenoids are associated with a reduced risk of cataracts and macular degeneration. While limiting egg consumption limits a major source of dietary cholesterol, it also limits an economical source of several important nutrients.
Summary
While dietary cholesterol, of which egg yolks are a major source, was once thought to play a primary role in determining plasma cholesterol levels, and therefore CHD risk, scientific opinion appears to be shifting to the belief that it may have a negligible effect in most healthy people.
The relationship between dietary cholesterol and serum cholesterol levels is complex and dependent on a large number of factors, such as dietary fiber, saturated fat, and polyunsaturated fat intake; obesity; insulin resistance; and genetics. Several lifestyle factors, such as smoking, inactivity, and overweight, are clearly associated with an increased CHD risk and also play integral roles.
The evidence overwhelmingly suggests there is no increased risk of CHD with egg consumption for healthy adults. There does, however, appear to be an increased risk of CHD associated with egg consumption for those diagnosed with diabetes.
— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Tex.
http://www.todaysdietitian.com/newarchives/060111p40.shtml
選擇“Disable on www.wenxuecity.com”
選擇“don't run on pages on this domain”
