People who survive heart attacks have a greater chance of living longer if they increase their dietary intake of fiber -- and eating lots of cereal fiber is especially beneficial, finds research published today on bmj.com.
Those who ate most fiber had a 25% lower chance of dying in the nine years after their heart attack compared with those who ate least fiber, the researchers found. Every 10g per day increase in fiber intake was associated with a 15% lower risk of dying over the nine-year follow-up period.
The researchers point out that with more people surviving heart attacks, it will be increasingly important to find out what lifestyle steps they can take alongside their medication to improve their long-term health prospects.
It is well-known that healthy people who have a high intake of dietary fiber have a lower risk of developing coronary heart disease but until now it has been unclear whether advising heart attack survivors to eat more fiber will improve their chances of living longer.
The research team, based in Boston, USA, therefore analyzed data from two big US studies, the Nurses' Health Study of 121,700 female nurses and the Health Professional Follow-up Study of 51,529 male health professionals. In both studies, the participants completed detailed questionnaires on their lifestyle habits every two years.
The researchers looked at the 2,258 women and 1,840 men who survived a first myocardial infarction (MI) -- a heart attack -- during the course of the studies. They were followed for an average of almost nine years after their heart attack, during which time 682 of the women and 451 of the men died.
Participants were divided into five groups (quintiles) according to how much fiber they ate after their heart attack. The top quintile -- the one in five who ate most fiber -- had a 25% lower chance of dying from any cause during the nine years after their heart attack compared with the bottom quintile -- the one in five who ate least fiber. When considering only cardiovascular causes of death (heart attack, stroke and coronary heart disease), the top quintile had a 13% lower mortality risk than the bottom quintile.
When the researchers looked at the three different fiber types -- cereal, fruit and vegetable -- only higher cereal fiber intake was strongly associated with an increased chance of long-term survival after a heart attack. Breakfast cereal was the main source of dietary fiber.
All the results were adjusted for other factors that might affect the chance of survival after a heart attack, including age, medical history and other dietary and lifestyle habits.
The researchers point out that heart attack survivors have a higher risk of dying than the general population and are often more motivated to make changes to their lifestyle -- yet treatment to improve their chances of living longer generally neglects the importance of a healthier lifestyle in favour of long-term medication.
'Future research on lifestyle changes post-MI should focus on a combination of lifestyle changes and how they may further reduce mortality rates beyond what is achievable by medical management alone,' they conclude.
High dietary fiber intake can improve blood lipid levels and reduce the risk of high blood pressure, obesity and diabetes while a low-fiber diet is associated with an increased risk of colorectal cancer.
Less than 5% of Americans consume the minimum recommended fiber intake of 25g per day for women and 38g per day for men. In the UK, adults are recommended to eat at least 18g of fiber daily but dietary surveys suggest people eat an average of only 14g.
- S. Li, A. Flint, J. K. Pai, J. P. Forman, F. B. Hu, W. C. Willett, K. M. Rexrode, K. J. Mukamal, E. B. Rimm. Dietary fiber intake and mortality among survivors of myocardial infarction: prospective cohort study. BMJ, 2014; 348 (apr28 8): g2659 DOI: 10.1136/bmj.g2659
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