Dietary interventions and nutritional supplements for heart failure: a systematic appraisal and evidence map.

Aims To appraise meta-analytically determined effect of dietary interventions and nutritional supplements on heart failure (HF)-related outcomes, and create an evidence map to visualize the findings and certainty of evidence. Methods and results Online databases were systematically searched for meta-analyses of randomized controlled trials (RCTs) evaluating the effect of dietary interventions and nutritional supplements on HF outcomes and incidence. These were then updated if new RCTs were available. Estimates were pooled using a random-effects model and reported as risk ratios (RRs) or mean differences with 95% confidence intervals. We identified 14 relevant meta-analyses, to which 21 new RCTs were added. The total evidence base reviewed included 122 RCTs (n = 176 097 participants) assessing 14 interventions. We found that coenzyme Q10 was associated with lower all-cause mortality [RR 0.69 (0.50-0.96); I2 = 0%; low certainty of evidence] in HF patients. Incident HF risk was reduced with Mediterranean diet [RR 0.45 (0.26-0.79); I2 = 0%; low certainty of evidence]. Vitamin E supplementation was associated with a small but significant increase in the risk of HF hospitalization [RR 1.21 (1.04-1.40); I2 = 0%; moderate certainty of evidence]. There was moderate certainty of evidence that thiamine, vitamin D, iron, and L-carnitine supplementation had a beneficial effect on left ventricular ejection fraction. Conclusion Coenzyme Q10 may reduce all-cause mortality in HF patients, while a Mediterranean diet may reduce the risk of incident HF; however, the low certainty of evidence warrants the need for further RCTs to confirm a definite clinical role. RCT data were lacking for several common interventions including intermittent fasting, caffeine, DASH diet, and ketogenic diet. More research is needed to fill the knowledge gap.