BMJ with analysis of the Nurses Health Study (32 years of followup) and Health Professional Follow-up Study (22 years of followup), 2 large prospective US studies, found a beneficial role of fiber in patients surviving an MI (see DOI: 10.1136/bmj.g2659). they assessed covariates, such as other dietary components, medication use, medical history and lifestyle factors, though were unable to control for family history of MI, hypercholesterolemia, polyunsaturated fat intake, multivitamins, glycemic index, site of MI, ST elevation and initial creatinine level.
In this prospective cohort study, they found:
–2258 women and 1840 men initially free of cardiovascular disease, stroke or cancer at the time of enrollment, then survived an MI in followup and completed food frequency questionnaires both before and after their MI
–Comparing the top fifth of post-MI fiber consumption to the lowest fifth: there was a 25% reduction in all-cause mortality–HR 0.75 (0.58-0.97). Those with highest intake of cereal fiber had a slightly lower mortality than with other fiber sources (fruit or vegetable fiber) –HR 0.73 (0.58-0.91).
–People who increased their fiber after the MI also with significant benefit –HR 0.69 (0.55-0.87)
–With fiber assessed as a continuous variable, the benefit was 15% for a 10g/day increment in fiber — HR 0.85(0.74-0.97)
–no difference if control for BMI, physical active, glycemic load, aspirin or lipid-lowering medication
In these types of studies, it is often hard to attribute a single intervention (high fiber foods) from more general changes (those who eat higher fiber foods may do other healthful behaviors, such as eating other healthy foods or exercising more). There may be some specific benefits of fiber itself (improved insulin sensitivity, improved glycemic control, increase in short chain fatty acid production, increased satiety, reduced systemic inflammation, reduced LDL, reduced lipid peroxidation, and beneficial gut microbiota environment) but the main point here is that healthy diets are beneficial. This benefit is on top of using statins post-MI. which really brings me to my major concern: there have been a few studies showing that prescribing statins lead to less healthy eating (since the statins work so well). Some of this may be because patients are happy with the lipid outcomes they see with the statins and that lifestyle changes are so much harder than taking a pill (and often with less dramatic results than the pill). But part of the problem may be that providers are less vigilant in promoting healthy lifestyles in patients who have such good-looking lipids. And, this study reinforces that healthy lifestyle is an added benefit to statins in preventing all-cause mortality (and, to a lesser extent, cardiovascular mortality). And healthy lifestyle has additional benefits (preventing/helping treat diabetes, or obesity, or stress-related problems, or perhaps several different cancers, or alzheimers?, some data that Mediterranean diet is helpful).
Geoff