A meta-analysis evaluating the efficacy of dietary supplements containing vitamins and antioxidants in the prevention of cardiovascular disease.
A meta-analysis of Korean Myung and colleagues published in the journal British Medical Journal in 2013 estimated, from the results of 50 controlled randomized trials, the efficacy of food supplements containing vitamins and / or antioxidants in prevention primary and secondary cardiovascular disease. The results indicate that the daily intake of these supplements reduced the risk of cardiovascular disease in adults eating a balanced way. Worse, high-dose use may be hazardous to health.
The Study Rationale
Cardiovascular diseases are the leading causes of death and disability worldwide. In recent decades, epidemiological studies have shown that consumption of fruits and vegetables rich in vitamins and antioxidants would reduce this risk. 600 grams of fruit and vegetables consumed per day would reduce by 31% the number of ischemic heart disease and 19% stroke. One promising avenue of research which benefits were obtained in animals is to offer healthy or at risk of cardiovascular disease to take a supplement to ensure the supply necessary vitamins and antioxidants daily.
Randomized controlled trials have attempted to answer this question, but the results seem contradictory. A meta-analysis can help to see more clearly.
Daily consumption of a food supplement containing vitamins and antioxidants could potentially decrease the risk of cardiovascular disease in some studies. Must still prove. This is what is attached to this review question.
It warns the daily consumption of a food supplement containing vitamins and antioxidants the occurrence of cardiovascular disease?
The meta-analysis of Korean Myung and colleagues chose 50 randomized controlled trials involving a total of 294,478 participants. The age of participants was between 49 and 82 years. These trials were designed to test the effectiveness of dietary supplements containing vitamins and antioxidants on the primary and secondary prevention of cardiovascular disease. Methodological quality was assessed for each clinical trial. The duration of the intervention with follow-up period ranged from 6 months to 12 years and the number of participants ranged from 61 to 39,876 depending on the study.
Subgroups were made according to the type of prevention (primary, secondary), the type of supplements (quality and dose), the type of outcome (cardiovascular death, angina pectoris, myocardial infarction, stroke cerebral or transient ischemic attack), duration of treatment (less than 5 years or not less than 5 years), type of control (placebo or not), the number of participants (less than 10 000 or greater or equal to 10000 ) and the prescribed type of dietary supplement (vitamins, antioxidants, or combined).
The Non-Pharmacological Intervention (NPI) assessed
Dietary supplements included vitamin A, B6, B12, C, D, E, beta-carotene, folic acid and selenium. The daily dose was administered but the amount varied according to studies.
The results showed no beneficial effect of dietary supplements containing vitamins and antioxidants in most subgroups of the meta-analysis. In other words, taking a daily dietary supplement does not reduce the risk of cardiovascular disease regardless of the type of vitamin and antioxidant or combination of them, the type of cardiovascular disease, supplements consumption duration, producer of food supplements, the nature of the control group and the methodological quality of studies.
The high-dose consumption of these supplements could instead have deleterious health effects.
A primary or secondary prevention based on the daily intake of a food supplement containing vitamins and / or antioxidants are not effective in reducing the risk of cardiovascular disease.
What it means for General Population
Food supplements containing vitamins and antioxidants have no effect on cardiovascular disease prevention for balanced eating people. The high-dose consumption of these supplements could instead have deleterious health effects.
What it means for Healthcare and Prevention Professionals
Food supplements based on vitamins and / or antioxidants consumed daily had no effect on the primary or secondary prevention of cardiovascular disease. This applies regardless of the type of vitamins and / or prescribed antioxidants, and their shelf life.
What it means for Researchers
This meta-analysis performs a literature synthesis of 50 randomized controlled trials testing the effectiveness of the daily intake of vitamins based dietary supplement and / or antioxidants in the primary or secondary prevention of cardiovascular disease, ie healthy people with or at risk for cardiovascular disease eating a balanced way. The results show no benefit of supplements regardless of the methodological quality of studies, supplements consumption duration and type of supplements (combined or not). Clinical trials should focus on studying people deficient in vitamins and antioxidants.
What it means for Policymakers
Many people buy supplements believing beneficial to their health. For people eating a balanced way, this meta-analysis shows no benefit of taking daily supplements containing vitamins and / or antioxidants in the prevention of cardiovascular diseases. Governments and regulators should require evidence of effectiveness and safety of these supplements before they are marketed as is the case in medicine.
Myung SK, Ju W, Cho B, Oh SW, Park SM, Koo BK, Park BJ (2013). Efficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis of randomised controlled trials. British Medical Journal, 346, 1-22.
Related articles on Blog en Sante ©
To reference this Blog en Sante © article.
Ninot G (2015). Dietary supplements do not protect against cardiovascular disease. Blog en Sante, A64.
© Copyright 2015 Gregory Ninot. All rights reserved.