For more than 60 years we have heard that saturated fat and cholesterol may be the driving forces behind the high rate of heart attacks in North America. A new study shows strong statistical links between eating a lot of high-cholesterol animal products — eggs, meat, poultry, and dairy — and risk for heart attacks. These researchers believe that eating a little bit of cholesterol may not be harmful, but the more you take in, the greater your risk for heart disease and death. Their review of six prospective studies with close to 30,000 participants, followed for an average of 17 or more years, found that eating 300 mg of cholesterol per day is associated with a 17 percent increased risk for heart disease and 18 percent increased risk for premature death from any cause (JAMA, March 19, 2019;321(11):1081-1095). These numbers are only an average; some people suffer a genetic risk for developing higher blood cholesterol levels after eating foods that contain cholesterol, while others can eat a moderate amount of cholesterol-rich foods without suffering high blood cholesterol levels.
An editorial in the same issue says, "The association of dietary cholesterol with cardiovascular disease, although debated for decades, has more recently been thought to be less important . . . This report is far more comprehensive, with enough data to make a strong statement . . . overall dietary cholesterol intake remains important in affecting the risk of [heart attacks] and more so the risk of all-cause mortality" (JAMA, March 19, 2019;321(11):1055-1056). More than 40 percent of North Americans die of heart attacks, and high blood cholesterol is unquestionably associated with increased risk for heart attacks.
Dietary Cholesterol or Saturated Fat?
This is probably the most comprehensive study on dietary components and heart attacks, and it supports other studies showing that heart attacks are linked to dietary cholesterol far more than to dietary saturated fat. For example, saturated fats from plants have not been shown to cause heart attacks, even though they do raise blood levels of the harmful LDL cholesterol associated with increased heart attack risk. Meat and eggs contain primarily long chain saturated fats, while plants rich in saturated fats, such as coconut, palm, and palm kernel oils, contain shorter chained saturated fats. People who eat saturated fats from plants are at reduced risk for heart attacks. This new study shows that people who eat more short-chain saturated fats found in dairy products are not at the same high risk for heart attacks as those who eat the longer chain saturated fats in meat and eggs. It is controversial whether dairy products are safer than meat and eggs as they all contain saturated fats and cholesterol. In addition, milk contains a lot of the pro-inflammatory sugar, galactose.
The researchers have not proven that dietary cholesterol causes heart attacks, they have only shown that eating these foods is associated with increased risk for heart attacks. Cholesterol may not be the culprit; it may just be a marker for some other factor from these foods such as TMAO or Neu5Gc, or their lack of fiber, which is found only in plants.
This study and many others suggest that the U.S. dietary guidelines need to be revisited. The current guidelines contain no specific limit on dietary cholesterol, while guidelines before 2015 recommended limiting dietary cholesterol to less than 300 milligrams per day. This is less than the amount of cholesterol in two eggs. Since cholesterol is found in varying amounts in meat, poultry and dairy as well as in eggs, this study supports the diet I have recommended for many years: heavy on plants and light on animal products.