In an apparent attempt to taint the remaining vegetables that haven’t been Daily Mail-ized, some of the popular media has turned against asparagus over the last few days. It turns out, asparagus gives you breast cancer! For once, some of the media also started fighting back, in an attempt to explain why the winter vegetable is not, in fact, a danger to anyone’s health. As a scientist and a student of science communication in the mass media, I believe there is much to be learnt from the recent kerfuffle.
It all started when a group of scientists from Cold Spring Harbor published an article in the prestigious journal Nature showing that breast cancer cells that are capable of spreading around the body and forming secondary tumors – or metastases – have an enhanced ability to benefit from the amino-acid asparagine. This study also shows how when breast cancer cells are stopped from “digesting” asparagine or when asparagine intake is diminished breast cancer does not spread quite as efficiently, which means a better chance of survival. All these studies were conducted in mice, which while not a perfect model for humans are actually a pretty reliable system to study cancer.
The next step in the media food-chain was the popular media – starting with the usual suspects – declaring that if cutting asparagine intake in the diet of mice who already have cancer decreases the risk of said cancer spreading, this means that eating asparagus as a healthy person probably will give you cancer you did not have. There are three things wrong with this idea. First of all, cancer forming and cancer spreading are two completely different processes. There are even some molecules that help prevent cancer from forming, but actually help pre-existing cancer survive and spread around the body. Secondly, this study was carried out in mice, which means that a lot of work needs to be done before we can draw a direct parallel with humans. Thirdly, and crucially, the Nature study compared mice that were given no asparagine at all to mice whose diet was made of of 4% asparagine.
Let’s put this number into context. 180 grams cup of asparagus has 616 milligrams of asparagine, which is about 0.3%. This means that even if you literally only ate asparagus you would not get enough asparagine in your diet to match the levels in the study. What’s more, your body naturally produces asparagine, which means that even eating none at all would still not bring your total levels of apsaragine to 0. What this study suggests to a scientific audience is that breast cancer patients who have been shown to show the appropriate molecular markers could be given supplements that scavenge the asparagine already in their system – which is the only real way to bring it down.
What’s been really encouraging this week is that if you follow the media you did about this and about the great science that is actually contained in the Nature article. All types of news outlets have been letting us know about why the asparagus=cancer nonsense is anti-scientific, wrong and probably dangerous and have been explaining how the Nature article in question is actually really good science in its own regard, without having to get all tangled up in vegetables.
For once, here’s to the media! You caught this one in time, guys.