A recent, soon to be published study by the prestigious Centre for the Understanding of Nutritional Technology and Science has found that consumption of more than two servings of tofu (a soybean derived food product) per week may lead to a loss of IQ.
The study, conducted over a number of years, looked at the effect of varying degrees of tofu consumption on subjects’ scores in standardised IQ tests. Even when allowing for other factors that have been previously indicated to negatively effect intelligence, the results were “damning”, according to the study’s conclusion. In an interview, a representative of the Centre declared that he and his team are satisfied that they have achieved a significant breakthrough in our understanding of tofu, and have proven beyond doubt that, when consumed in greater than normal amounts, it does make humans more stupid. He added: “We have yet to prove a link between tofu and obesity, but our research continues.”
I’m sure that you will be aware of a number of stories that have made the news in recent years, linking consumption of certain foods, particularly red meat, to various diseases. If you want to read rebuttals of news stories like Red Meat Causes Cancer, or the more recent High Protein Diet as bad as 20 Cigarettes per Day, or simply to read about the problems inherent in these kinds of studies, you can do so here, here and here. This is the territory of people with degrees in medicine or biochemistry, neither of which I have. Instead here are a couple of questions that we should all be asking ourselves when faced with news stories that make these kind of alarming food related claims.
The first is, what’s the agenda? As the articles I linked to above point out, epidemiological studies (that look for patterns, or associations) almost inevitably start out looking for specific patterns – in other words, researchers don’t set out to see if they can spot any patterns at all, they go looking for a specific one. If you go looking for a specific pattern the chances are that you will lean towards finding evidence to support it. Epidemiology might support a hypothesis, but never proves it. T. Colin Campbell, one of the authors of the “China Study”, is well known as an advocate for a vegan diet, and (to quote Wikipedia): “The authors conclude that people who eat a whole-food, plant-based/vegan diet—avoiding all animal products, including beef, pork, poultry, fish, eggs, cheese and milk, and reducing their intake of processed foods and refined carbohydrates—will escape, reduce or reverse the development of numerous diseases.”
So, if I write a story about the link between tofu consumption and reduced IQ (let’s be totally honest, and in case you didn’t guess, I made that up), you would need to ask yourself why I went looking for such an association in the first place. Perhaps I’m some kind of omnivorous fundamentalist who thinks that soy products are rooted in evil….
The second, and perhaps more significant question is, (to quote Robb Wolf) “What is the mechanism?” Unless there is a viable explanation for why heavy tofu consumption causes a loss of IQ (I just had a thought – imagine if my made up story turns out to be true!), then it’s simply an association that may be a complete coincidence. A favourite analogy is ‘Fire engines cause fires’ – because studies show that there is a strong association between buildings on fire, and the presence of fire engines. Or even better, if you didn’t follow the link to Dr Briffa’s article above: ‘ice cream causes shark attacks’.
Who can blame researchers who want to catch some headlines? Both of the UK broadsheet newspapers that carried this story had some caveats, if you read to the end, but the headlines and the accompanying pictures are what stay with you (do you think tofu seems more sinister when I include a picture of a brain scan?) It’s too bad that the news media we appear to want is that which scares, rather than informs.