Guest blog: Today we’re kicking off National Heart Month with this guest blog, written for us by Dr Harry Boardman, who is part way through his Cardiology specialist training in Oxford.
Something to think about while you are lining your vitamin and antioxidant tablets up next to the marmalade on the breakfast table tomorrow morning, do they really help you live longer? The British Medical Journal has just published a meta-analysis (a merging of several trials for greater accuracy and to minimise bias) comparing almost 300,000 people in 50 trials of whom half were randomly assigned to Vitamins or Antioxidants, the other half to placebo (sugar pills). The supplements they assessed were vitamins A, B6, B12, C, D, E, folic acid, β Carotene and Selenium.
These trials compared whether those who took the supplements, as opposed to the sugar pill, had fewer heart attacks and were less likely to die. They looked at two different types of people, those who were essentially healthy to see if the supplements would avoid a first heart attack or death (primary prevention) and those who already had cardiovascular problems (a higher risk population) from having further heart attacks or dying (secondary prevention). They assessed supplements, the vitamins and antioxidant individually as well as together. The majority of trials (42) were funded by government or public organisations, only 5 reported pharmaceutical industry funding, 2 did not report how they were funded.
Overall, vitamin and antioxidants had no effect on cardiovascular disease or death. However, on breaking down the data into specific supplements there was a very mild reduction in heart attacks and deaths from heart attacks in those who took Vitamin B6, however when the authors assessed just those trials which were judged to be of high quality with minimal bias this benefit disappeared.
The authors concluded:
In this large scale meta-analysis of randomised controlled trials, we found no evidence to support the use of vitamin or antioxidant supplements for the primary or secondary prevention of major cardiovascular events. Furthermore, these supplements were not associated with any reduced risk of such events in the subgroup meta-analyses according to various factors such as type of vitamins and antioxidants, type of cardiovascular outcomes, study design, methodological quality, duration of treatment, funding source, provider of supplements, type of control, number of participants in each trial, and supplements given singly or in combination with other vitamins or antioxidant supplements.
The article states that we cannot draw comparisons that eating foods high in vitamins and antioxidants (such as fruit and vegetables) is not helpful. We also don’t know whether supplements would benefit people who are known to be deficient in those vitamins or antioxidants which are supplemented as this meta-analysis did not specifically assess that population. However it is food for thought when popping these pills everyday as to whether it doing anything beneficial to health at all.
Seung-Kwon Myung, Woong Ju, Belong Cho, Seung-Won Oh, Sang Min Park, Bon-Kwon Koo, Byung-Joo Park for the Korean Meta-Analysis (KORMA) Study Group. Efficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis of randomised controlled trials. BMJ 2013;346:f10