Fiber Reduces Heart Attack Risk

Updated September 18, 2013

“Vegetable, fruit, and cereal intake and risk of coronary heart disease among men” by Eric Rimm in the February 14, 1996 issue of the Journal of the American Medical Association found the more fiber you eat the less your risk of heart disease (275:447). This study examined food intakes of 51,529 men in various medical fields in the Health Professionals Follow-up Study. Those in the lowest fiber group ate 12.4 grams of fiber daily and those in the highest group ate 28.9 grams. According to the authors, “These results support current national dietary guidelines to increase dietary fiber intake and suggest that fiber, independent of fat intake, is an important dietary component for the prevention of coronary disease.” “…the positive association between saturated fat intake and coronary heart disease is almost entirely explained by lower fiber intake among men who consum ed more fat.” Of the three main contributors to total fiber intake–vegetable, fruit, and cereal–cereal fiber was found to be most strongly associated with a reduced risk of heart attacks.


Fiber is only present in plant foods. There is not a speck of fiber in any chicken, beef, fish, egg, or dairy product. The average American eats 10 grams of dietary fiber a day. People following the McDougall diet eat 40 to 60 (sometimes 100) grams a day. Fibers have been roughly divided into soluble (prevalent in oats and beans) and insoluble fibers (wheat). Soluble fibers have been shown to lower “bad” LDL cholesterol, especially when fed to people with high cholesterol levels and when fed in large amounts. Fiber binds bile acids in the intestine and causes them to be eliminated in the stool. Bile acids are made from cholesterol. Thus, loss of bile acids removes cholesterol from the body. For every gram of fiber consumed there is a 0.5% to 2% reduction in blood cholesterol.

Fiber may have other benefits. Fiber lowers insulin levels, and high levels of insulin are associated with more heart disease. Fiber decreases the blood’s tendency to clot — a blood clot in the heart artery causes the death of the heart muscle.

Arguing which is the most important contributor to heart disease — dietary fiber, cholesterol, or saturated fat — is of no practical importance. Who cares? The foods that are high in fiber (plants), contain no cholesterol, and are low in saturated fat. Unhealthy red meat, poultry, fish, eggs, and dairy products are high in cholesterol, lack fiber, and are all high in saturated fats (except for some fish). The consumers are left with easy choices when they know the simple nutritional qualities of foods.

John McDougall, MD