NHS Direct Online has released its opinion of the FSA report and criticises in particular inaccuracies in the media reporting. It also stresses no systematic review methodology was used therefore it is "not possible to decide how reliable the conclusions might be."
The news that vitamins could damage your health was reported in eight newspapers (1-10) on Thursday 8th May 2003, with a mixed degree of accuracy. The articles were based on an FSA press release and detailed report from the Expert Group on Vitamins and Minerals (11,12) which issued warnings about vitamins and minerals.
Eight newspapers (1-10) reported the news that vitamins could damage your health. The newspaper articles gave varying details of the vitamins and minerals that had had warnings issued about them by the Food Standards Agency (FSA).
The newspaper articles were based on a large, detailed report by the Expert Group on Vitamins and Minerals (EVM) (11), and a press release (12) issued by the FSA. The EVM report contained a series of risk assessments to determine the safe upper dose limits for vitamins and minerals. It did not investigate possible benefits of the supplements. Following publication of the EVM report, the FSA issued advice on some vitamins and minerals that could have possible harmful effects if taken in too high a dose (13).
Some of the newspaper articles inaccurately stated that the EVM report said that vitamins and minerals were a waste of money, and that many vitamin supplements did more harm than good. Only one newspaper article emphasised that the EVM report made no judgement on the health benefits claimed for various supplements.
Evaluation of the evidence base for safety of high doses of vitamins and minerals
Where does the evidence come from?
The review was carried out by the Expert Group on Vitamins and Minerals (EVM): an independent group established by the UK government in 1997. The group was comprised of eleven members from the medical and scientific community, one lay member and four observers representing consumer organisations, the health and food industries and alternative medicine interests. Possible competing interests of the members of the EVM were reported; none seemed to be relevant.
What were the authors' objectives?
To advise on safe upper limits (SULs) of intakes of vitamins and minerals in food supplements and fortified foods. The EVM were asked to consider only vitamins and minerals sold under food law. Review of nutritional or non-nutritional beneficial effects or non-nutritional use in medicine was outside the review objectives.
What was the nature of the evidence?
A non-systematic review. The EVM considered a detailed review of the relevant evidence for each substance and produced a 'Risk Assessment' and 'Establishment of Guidance Level' based on this evidence. The detailed reviews covered nutritional and toxicological information. The report stated that because of the diversity of the available data no formal systematic review methodology was used during the assessment process. However, the authors of the reviews of particular vitamins or minerals which were commissioned to inform the report, and the EVM, considered the strengths and weaknesses of study design and conduct in assessing the quality and reliability of particular studies. Both human and animal studies were included, as well as exposure data taken from UK Government Departments and from other scientific literature. Further details are given in the report.
For each of the 34 substances assessed, a 'Risk Assessment' and 'Establishment of Guidance Level' were reported.
What were the authors' conclusions?
Following publication of the EVM report, the FSA issued advice on some vitamins and minerals that could have possible harmful effects if taken in too high a dose (13).
How reliable are the conclusions?
The report is very large and is based on separate reviews of the evidence for each of the 34 substances included. Some details of the EVM's methodology are given in one of the Annexes to the report. No details of the methodology of the separate reviews were given, other than the statement that systematic review methodology was not used. It is therefore not possible to give a detailed appraisal of the methods used, or to decide how reliable the conclusions might be.
Information staff at CRD searched for systematic reviews relevant to this topic. Systematic reviews are valuable sources of evidence as they locate, appraise and synthesize all available evidence on a particular topic.