Diet plays an important role in the cause of atherosclerosis and coronary heart disease; however, secondary prevention guidelines generally emphasize pharmaceutical management owing to the lack of evidence to guide diet and lifestyle recommendations.
High intake of dietary fiber has been linked to a lower risk of heart disease in a number of large studies that followed participants for many years. One such study conducted by Harvard researchers of 43,757 US male health professionals 40 to 75 years of age had found high dietary fiber intake lowered the risk heart disease by 40%. However, it remains unclear if advising heart attack survivors to consume more fiber will extend their life span.
Researchers from various institutions in Boston, Massachusetts, examined data from two large prospective cohort studies; the Nurses’ Health Study and the Health Professionals Follow-Up Study.
This prospective cohort study included 2,258 women and 1,840 men, who were free of cardiovascular disease, stroke, or cancer at enrollment, survived a first heart attack during follow-up, and were free of stroke at the time of the initial heart attack. Participants filled out food frequency questionnaires before heart attack and at least one after heart attack.
Participants were followed for 8.7 years for women and 9.0 years for men. During that there were 682 total and 336 cardiovascular deaths for women, and 451 total and 222 cardiovascular deaths for men.
Participants were divided into five groups according to the amount of fiber consumed after their heart attack.
The results the group with the highest fiber intake was significantly associated with 25% lower all-cause mortality during the nine years after heart attack compared to those who consumed the least amount of fiber.
When looking at cardiovascular mortality, those with the highest fiber consumption had a 13% lower risk of cardiovascular death compared to those who consumed the least amount of fiber.
When researchers examined the three types of fiber; cereal, fruit and vegetable, high intake of cereal fiber was strongly associated with long term survival from all causes after their heart attack compared to other fiber sources.
In their conclusion the researchers write “In this prospective study of patients who survived MI, a greater intake of dietary fiber after MI, especially cereal fiber, was inversely associated with all cause mortality. In addition, increasing consumption of fiber from before to after MI was significantly associated with lower all cause and cardiovascular mortality.”
The researchers point out in their discussion in the general population, a 20-40% risk reduction in coronary heart disease has consistently been observed among those who consume fiber-rich whole grains regularly, however less than five percent Americans consume the minimum recommended fiber intake of 25 g/day for women and 38 g/day for men.
The researchers acknowledge that there were limitations to this study, including the results may be confounded by beneficial factors related to fiber intake; foods that are high in fiber, such as whole grains, fruits, and vegetables, also contain vitamins, minerals, antioxidants, and phytochemicals, which may also be beneficial for health.
The study’s strengths included large sample size and long duration of follow-up from two prospective cohort studies, with follow-up rates in excess of 90% in each two year cycle.
This study is published in BMJ.
Researchers came from the following institutions; Harvard School of Public Health, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center.