Showing the importance of evidence

Late last month, I attended the MRC Early Career Scientist Conference which was two days of young scientists talking about the work they were doing. I got to hear about the different research being conducted all around the country and there were a few presentations that I want to share with you because they show how relevant evidence can be to people’s daily lives and come from a South African context. As far as I know all the research that was presented is unpublished and all I have to go by in reporting is my memory and the one page abstracts in the conference booklet.


The first presentation was An Assessment Of Different Soil Types Generally Consumed By Pregnant Women In South Africa by Oluwole Olowoyo from the University of Limpopo. This one first caught my attention because it’s about people eating soil. I hadn’t heard of that before, though when the topic came up in the lab I found out it was actually quite well known as Pica.

Eating soil is an accepted cultural practice in some parts of Africa and Olowoyo was able to buy soil for eating from a vendor on the side of the road. Part of the reason for soil consumption was the belief that it could help replace certain minerals that the pregnant mother might lack, such as iron. This is an old cultural belief and not based on any sort of systematic evidence. When Olowoyo looked at the soil he did indeed find iron, but he found it in a form that is actually toxic. In addition he found that consuming the soil placed a person at risk of health problems due to lead and manganese in the soil.

Here we have a cultural practice that people follow, without evidence, to try keep themselves healthy but when the soil samples are actually analysed we see that they have an increased risk of toxicity. This is the danger of beliefs and cultural practices that are not based on reliable evidence, the very thing you are doing or recommending for your own or someone else’s good may actually be harming them more than helping them. This isn’t limited just to ancient cultural beliefs though, as we will soon see.


The next story contains a warning. There was a presentation given by Prudy Seepe from the University of KwaZulu-Natal titled Screening Of “Umuthi Wesifuba/Sethlare Sa Mafathla” African Traditional Mixtures Used In The Management Of Tuberculosis. She described how she looked at two traditional herbal remedies used for treating TB and whether they had any anti-microbial properties. Her presentation showed that both mixtures did have anti-microbial properties. That seems to say two important things; firstly, that traditional medicines may be effective against TB and, secondly, that further investigation of the remedies is needed to find the active ingredients.

Unfortunately, in the question session, it emerged that the first may not be true. Someone in the audience pointed out that her extractions were done using toxic chemicals and did not represent how people would consume traditional medicines. She then explained that she had looked at anti-microbial properties when the mixtures were prepared according to the traditional healer’s instructions but that that did not have any effect! That means while there may be active ingredients worth looking for, the mixtures are unlikely to have any health benefit.

That question serves as a very important warning about looking critically at research, something which can be hard but which is an important skill to try cultivate. It also shows us how our views can (and should!) change as new evidence comes in and, following on, the importance of publishing all results, including negative. It’s only when we publish all our data that we can avoid the problems of publication and the dangerous consequences of incomplete data. The last point is the subject of a new book by Ben Goldacre, the foreword of which can be read here.

Also I want to state that I’m not saying Seepe was deliberately doing anything wrong. The push to publish positive results is a systemic issue, everybody slips up and makes mistakes and it looks like she’s doing good work in trying to bring scientific evidence to traditional medicine.


The last story again reminds us to be careful and that people will lie to us if it’s for their own good. Anel Schoonees from the Centre for Evidence Based Health Care at the University of Stellenbosch presented The Advertising Of Nutritional Supplements In South African Women’s Magazines: Descriptive Survey. An abstract from an early stage of the project can be read here. In short, the advertising of nutritional supplements is misleading.

Schoonees found that 86.7% of the adverts made health claims but only 6.6% of them cited research to support those claims. That means more than 90% of the claims were made without any attempt to provide evidence for them. This means we have no way of knowing if they are just making things up or if, as we saw above, the evidence might have been flawed. She did follow up on the cited research for those adverts that provided it and it was judged to be largely inappropriate! Sometimes the research is actually saying the opposite thing to which the advert would have you believe. In her earlier abstract Schoonees writes:

In one advertisement of a calcium-magnesium supplement, a good quality meta-analysis of randomised controlled trials is cited. Ironically, the study authors concluded that calcium supplementation is associated with about a 30% increase in the incidence of myocardial infarction.

The problem is even greater than just misleading advertisements as there is almost nothing that can currently be done about it. Medicines are strictly regulated but nutritional supplements do not count as medicines so are free from that and Schoonees described her struggles to get any sort of body interested in regulating supplements. This work is important because it shows that, to some people, evidence and the public’s health are not as important as money. Nutrition and “alternative” medicine is filled with people trying to con you, whether knowingly or not, and it’s important to make sure the evidence stands up before buying such products.


2 thoughts on “Showing the importance of evidence

  1. Good article! We are linking to this particularly great article on our website. Keep up the great writing.

  2. Pingback: Two years, still going strong | Evidence & Reason

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s