Scott Kahan, MD, MPH; Yoni Freedhoff, MD
Do long-term interventions (≥ 6 mo) to reduce and/or modify dietary fat reduce mortality, cardiovascular (CV) mortality, or CV morbidity?
Included studies compared interventions to reduce and/or modify dietary fat (dietary advice, supplements, or a provided diet) with usual, control, or placebo diets in adults with or without CV disease, and were ≥ 6 months in duration. Reduced-fat diets aimed to decrease fat intake to < 30% energy and partially replace energy lost with carbohydrates, protein, or fruit and vegetables. Modified-fat diets aimed to include ≥ 30% energy from total fats and included higher levels of monounsaturated and polyunsaturated fats than usual diets. Exclusion criteria included acute illness; pregnancy or lactation; and dietary interventions of α-linoleic acid, omega-3 fats, or fish oils; high-fiber diets or garlic; varying forms of carbohydrates; increased protein and fat intake; fat substitutes; and enteral and parenteral feeds. Outcomes included mortality, CV mortality, and CV morbidity (nonfatal myocardial infarction, angina, stroke, heart failure, peripheral vascular events, or atrial fibrillation).
This was an update of a previous review. MEDLINE, EMBASE/Excerpta Medica, Cochrane Central Register of Controlled Trials, and reference lists of identified studies and reviews were searched to June 2010 for randomized controlled trials (RCTs). Experts were contacted. 48 RCTs (60 comparisons) met inclusion criteria. Interventions included reduced-fat diets (25 comparisons, n = 61 958), modified-fat diets (15 comparisons, n = 13 004), and reduced-fat and modified-fat diets (10 comparisons, n = 4931). 9 comparisons (n = 1290) directly compared low- with modified-fat diets, and 1 study was not classifiable. 36 comparisons met ≥ 5 of 8 quality criteria (higher score = lower risk for bias).
Meta-analysis showed that interventions to reduce and/or modify dietary fat reduced CV events but not mortality or CV mortality (Table). Subgroup analysis by type of intervention (reduced fat, modified fat, or reduced and modified fat) found no differences between intervention and control groups for mortality, CV mortality, or CV events (Table).
Interventions to reduce and/or modify dietary fat reduce cardiovascular events but not mortality or cardiovascular mortality.
*NS = not significant; other abbreviations defined in Glossary. RRR, NNT, and CI calculated from control event rates and relative risks in article using a random-effects model.
†Nonfatal myocardial infarction, angina, stroke, heart failure, peripheral vascular events, or atrial fibrillation.
Kahan S, Freedhoff Y. Review: Interventions to reduce or modify dietary fat reduce cardiovascular events. Ann Intern Med. ;156:JC1–5. doi: 10.7326/0003-4819-156-2-201201170-02005
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Published: Ann Intern Med. 2012;156(2):JC1-5.
Cardiology, Coronary Risk Factors, Dyslipidemia.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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