Vitamins in Heart Failure: Friend or Enemy?

BACKGROUND: The failing heart is characterized by a depleted metabolic energy reserve and the upregulation of several molecular mechanisms leading to cardiac hypertrophy, inflammation, fibrosis, angiogenesis, and apoptosis. Dietary or non-dietary supplementation of vitamins could potentially benefit energy balance. OBJECTIVE: The objective of the present study was to evaluate all available information on vitamins supplementation in patients with chronic HF for possible beneficial effect on metabolic, inotropic, chronotropic and hemodynamic indices. METHOD: We searched MEDLINE via Pubmed by using the following terms: "chronic heart failure" OR "cardiomyopathy" AND "vitamins", "vitamin A", "B complex vitamins", "vitamin C", "ascorbic acid", "vitamin D", "retinol", "vitamin E", "thiamine", "riboflavin", "niacin", "pyridoxine", "cobalamin", "folate", "pantothenic acid", "biotin", "tocopherol" and combinations of them. RESULTS: Data regarding supplementation of micronutrients in HF for most vitamins were sparse, and the inference about cardiovascular outcomes was obscured by the heterogeneity of studies, high inherent morbidity, and mortality of this group of high-risk patients, limited sample sizes in certain studies, unclear design and lack of head to head comparisons. Most vitamins in human trials failed to offer survival, or robust beneficial effect. Mostly indirect favorable evidence is derived from patients with deficiencies of certain micronutrients rather than their ad hoc supplementation. CONCLUSION: While vitamins and micronutrients are promising compounds for optimizing myocardial metabolism and homeostasis in HF, additional randomized clinical trials of larger scale are warranted to demonstrate the benefits of their supplementation in this high risk group of patients.