BACKGROUND: Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.
OBJECTIVES: To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA), monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.
SEARCH METHODS: We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) on 15 October 2019, and searched Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) on 17 October 2019.
SELECTION CRITERIA: Included trials fulfilled the following criteria: 1) randomised; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) compared with higher saturated fat intake or usual diet; 4) not multifactorial; 5) in adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 6) intervention duration at least 24 months; 7) mortality or cardiovascular morbidity data available.
DATA COLLECTION AND ANALYSIS: Two review authors independently assessed inclusion, extracted study data and assessed risk of bias. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses, funnel plots and GRADE assessment.
MAIN RESULTS: We included 15 randomised controlled trials (RCTs) (16 comparisons, 56,675 participants), that used a variety of interventions from providing all food to advice on reducing saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of combined cardiovascular events by 17% (risk ratio (RR) 0.83; 95% confidence interval (CI) 0.70 to 0.98, 12 trials, 53,758 participants of whom 8% had a cardiovascular event, I² = 67%, GRADE moderate-quality evidence). Meta-regression suggested that greater reductions in saturated fat (reflected in greater reductions in serum cholesterol) resulted in greater reductions in risk of CVD events, explaining most heterogeneity between trials. The number needed to treat for an additional beneficial outcome (NNTB) was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~four years for one person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 53. Subgrouping did not suggest significant differences between replacement of saturated fat calories with polyunsaturated fat or carbohydrate, and data on replacement with monounsaturated fat and protein was very limited. We found little or no effect of reducing saturated fat on all-cause mortality (RR 0.96; 95% CI 0.90 to 1.03; 11 trials, 55,858 participants) or cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 10 trials, 53,421 participants), both with GRADE moderate-quality evidence. There was little or no effect of reducing saturated fats on non-fatal myocardial infarction (RR 0.97, 95% CI 0.87 to 1.07) or CHD mortality (RR 0.97, 95% CI 0.82 to 1.16, both low-quality evidence), but effects on total (fatal or non-fatal) myocardial infarction, stroke and CHD events (fatal or non-fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.
AUTHORS' CONCLUSIONS: The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events. Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies, while effects of replacement with monounsaturated fat are unclear. The reduction in combined cardiovascular events resulting from reducing saturated fat did not alter by study duration, sex or baseline level of cardiovascular risk, but greater reduction in saturated fat caused greater reductions in cardiovascular events.
_3: ANTECEDENTES: La reducción y la modificación de grasas en la dieta tienen efectos diferentes sobre los factores de riesgo cardiovascular, como el colesterol en suero), pero sus efectos sobre los resultados importantes de la salud son menos claros.
OBJETIVOS: Evaluar el efecto de la reducción y / o modificación de las grasas de la dieta sobre la mortalidad, mortalidad cardiovascular, la morbilidad cardiovascular y los resultados individuales, incluyendo infarto de miocardio, accidente cerebrovascular y los diagnósticos de cáncer en ensayos clínicos aleatorios de al menos 6 meses de duración.
ESTRATEGIA DE BÚSQUEDA: Para esta actualización de la revisión, el Registro Cochrane Central de Ensayos Controlados (CENTRAL), MEDLINE y EMBASE, se realizaron búsquedas hasta junio de 2010. Referencias de los estudios incluidos y las revisiones también se comprobaron.
CRITERIOS DE SELECCIÓN: LOS ENSAYOS CUMPLIERON CON LOS SIGUIENTES CRITERIOS: 1) aleatorio con grupo de control apropiado, 2) la intención de reducir o modificar la ingesta de grasa o colesterol (con exclusión de omega-3 en exclusiva las intervenciones de grasa), 3) no multifactorial, 4) los seres humanos adultos, con o sin enfermedad cardiovascular, 5) la intervención de al menos seis meses, 6) la mortalidad o morbilidad cardiovascular de datos disponibles.
RECOPILACIÓN Y ANÁLISIS DE DATOS: número de participantes que experimentan los resultados de salud en cada grupo fueron extraídos de forma independiente de los efectos aleatorios duplicados y meta-análisis, meta-regresión, sub-agrupación, análisis de sensibilidad y gráficos en embudo se llevaron a cabo.
RESULTADOS PRINCIPALES: Esta revisión actualizada sugiere que la reducción de grasas saturadas, reduciendo y / o modificación de grasas en la dieta redujo el riesgo de eventos cardiovasculares en un 14% (RR 0,86, IC 95%: 0,77 a 0,96, 24 comparaciones, 65,508 participantes de los cuales el 7% tenían un evento cardiovascular, I2 50%). Subgrupos sugirió que esta reducción de eventos cardiovasculares se observó en los estudios de la modificación de la grasa (no la reducción - que se relaciona directamente con el grado de efecto en el colesterol sérico total y el LDL y los triglicéridos), de al menos dos años de duración y en los estudios de los hombres (no de las mujeres). No hubo efectos claros de la dieta cambios en la grasa sobre la mortalidad total (RR 0.98, IC 95%: 0,93 a 1,04, 71,790 participantes) o la mortalidad cardiovascular (RR 0,94, IC 95%: 0,85 a 1,04, 65.978 participantes). Esto no alteró con la sub-agrupación o análisis de sensibilidad.
Pocos estudios en comparación reduce con dietas ricas en grasas modificadas, la comparación tan directa no era posible.
CONCLUSIONES DE LOS REVISORES: Los resultados son indicativos de una reducción pequeña pero potencialmente importante en el riesgo cardiovascular en la modificación de las grasas en la dieta, pero no la reducción de la grasa total, en pruebas más largas. Consejos de estilo de vida a todos los que están en riesgo de enfermedad cardiovascular y reducir los grupos de riesgo de la población, debe continuar incluyendo la reducción permanente de la dieta de grasas saturadas y el reemplazo parcial de insaturados. El tipo ideal de grasas insaturadas no está claro.
Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.
OBJECTIVES:
To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA), monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.
SEARCH METHODS:
We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) on 15 October 2019, and searched Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) on 17 October 2019.
SELECTION CRITERIA:
Included trials fulfilled the following criteria: 1) randomised; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) compared with higher saturated fat intake or usual diet; 4) not multifactorial; 5) in adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 6) intervention duration at least 24 months; 7) mortality or cardiovascular morbidity data available.
DATA COLLECTION AND ANALYSIS:
Two review authors independently assessed inclusion, extracted study data and assessed risk of bias. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses, funnel plots and GRADE assessment.
MAIN RESULTS:
We included 15 randomised controlled trials (RCTs) (16 comparisons, 56,675 participants), that used a variety of interventions from providing all food to advice on reducing saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of combined cardiovascular events by 17% (risk ratio (RR) 0.83; 95% confidence interval (CI) 0.70 to 0.98, 12 trials, 53,758 participants of whom 8% had a cardiovascular event, I² = 67%, GRADE moderate-quality evidence). Meta-regression suggested that greater reductions in saturated fat (reflected in greater reductions in serum cholesterol) resulted in greater reductions in risk of CVD events, explaining most heterogeneity between trials. The number needed to treat for an additional beneficial outcome (NNTB) was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~four years for one person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 53. Subgrouping did not suggest significant differences between replacement of saturated fat calories with polyunsaturated fat or carbohydrate, and data on replacement with monounsaturated fat and protein was very limited. We found little or no effect of reducing saturated fat on all-cause mortality (RR 0.96; 95% CI 0.90 to 1.03; 11 trials, 55,858 participants) or cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 10 trials, 53,421 participants), both with GRADE moderate-quality evidence. There was little or no effect of reducing saturated fats on non-fatal myocardial infarction (RR 0.97, 95% CI 0.87 to 1.07) or CHD mortality (RR 0.97, 95% CI 0.82 to 1.16, both low-quality evidence), but effects on total (fatal or non-fatal) myocardial infarction, stroke and CHD events (fatal or non-fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.
AUTHORS' CONCLUSIONS:
The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events. Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies, while effects of replacement with monounsaturated fat are unclear. The reduction in combined cardiovascular events resulting from reducing saturated fat did not alter by study duration, sex or baseline level of cardiovascular risk, but greater reduction in saturated fat caused greater reductions in cardiovascular events.
