a) The study: The article published in the British Medical Journal attempted to answer whether eating rice causes Type 2 diabetes. First we need to assess the study design and how credible we think the work and results are. Amongst other things this involves looking at the statistical analyses and reviewing whether the authors have any financial gain from the resulting publication.

It is clear that similar but smaller studies have been done before in various populations around the world. This research was different in that it pooled the already published data from 4 such studies. In so doing the analysis was able to include just over 350,000 participants. This was therefore a relatively large study and this increases statistical credibility.

The studies were pooled and analysed by what is called a meta-analysis, this is a robust way of looking at statistical data. The scientific world uses these types of investigations in order to increase the likelihood of finding a meaningful result. Confidence in the study is increased by the knowledge that it was carried out by university academic researchers. In addition they stated that they have no financial relationship with any organization with an interest in the publication.

The 4 studies used in the analysis came from diverse communities (Chinese, Japanese, Australian and American) and they also looked at a variety of rice eating habits. Some communities eat a lot and others not so much. The results reported that for every bowl of white rice eaten (roughly 150g) there was an 11% increase in the risk of Type 2 diabetes. Further number crunching suggested that those who ate the most white rice were 27% more likely to develop type 2 diabetes than those who ate the least amount.

The article goes on to describe more details of a dose-response relationship, the more white rice you eat, the more likely the chance of developing diabetes. In Asians a highly significant risk was demonstrated but not so in western populations. This raised another question about whether this just showed up the influence of the family genetics in the incidence of Type 2 diabetes.

b) Criticisms and conclusions: First and foremost this study was an observational study. This means it therefore looked at an association and correlation between two different variables. In this case it was eating white rice and the incidence of Type 2 diabetes. Just finding a correlation does not demonstrate cause and effect because there will be many different reasons why people develop diabetes. For example in some populations eating lots of rice may be associated with increasing body weight and it may be just the weight that is the cause of the problem.

In the Asian community the larger numbers of people with diabetes might have been due to genetic factors. Although the study has tried to correct for these simple cofounding issues in their statistical analyses there are so many other possible complicating factors that drawing any conclusions proves impossible.

An observational study can never prove that something causes something else because of these cofounding factors. All that this observational study can do is to demonstrate an association between eating white rice and diabetes incidence. Controlled studies designed to prove cause and effect are needed to determine if rice actually does increase the risk of developing diabetes. The jury is therefore still out on this question.

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