Should we really avoid fat in diet? The beneficial effects of low carbohydrate diet versus low fat diet on cardiovascular health: a systematic review and meta-analysis

Abstract

Background: European Society of Cardiology and the American College of cardiology recommend a diet that is considerably low in fat (<35%) and high in carbohydrates (45-55%) for cardiovascular disease (CVD) prevention. However, recent evidence suggests that low-carbohydrate diets (LCD) can provide similar, if not, better CVD protection. Design: Systematic review and meta-analysis Methods: 3 databases were screened until 17th of August 2020 for randomized controlled trials (RCTs). Two investigators selected studies, extracted data, and assessed risk of bias. Certainty of evidence was evaluated using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. Weighted mean differences and 95% confidence intervals were calculated. Results: 25 trials with a total of 2438 patients were included. LCD resulted in greater reductions in body weight (WMD -1.93 (95% CI -2.69, -1.16) kg; p<0.0001), triglycerides (WMD -26.13 (95% CI -23.45, -14.29) mg/dL; p<0.0001), TNF-alpha (WMD -0.5 (95% CI -0.82, -0.17) pg/mL; p=0.003) and IL-6 (95% CI -2.29, -0.59) pg/mL; p=0.0009) with a greater increase in HDL-C (WMD 3.73 (95% CI 2.92, 4.54) mg/dL; p<0.00001) and LDLC (WMD 5.07 (95% 1.9, 8.23) mg/dL; p=0.002) compared to low fat diet (LFD). There was no statistical difference in systolic (WMD 0.5 (95% CI -1.06, 2.05) mmHg; p=0.53) and diastolic blood pressure reduction (WMD -0.22 (95% CI -1.35, 0.91) mmHg; p=0.70). Conclusions: Obese patients with other cardiovascular risk factors assigned to an LCD achieved greater reductions in weight loss and triglycerides levels with a greater increase in HDL-C levels and a more pronounced anti-inflammatory state than patients assigned to an LFD. Hence, low carbohydrate diets could be an alternative tool for cardiovascular protection in selected patients. (Figure Presented).