Can toasters cause cancer? Might green beans add years to our life? Not all scientific evidence is created equal, says medical scientist and accredited nutritionist Dr Federica Amati. Here, she shares strategies for deciding how seriously to take the viral health headlines.
Let’s take a look at how science ‘works’. Scientists fall largely into three simplified categories. First, there are laboratory scientists who run experiments in lab coats, have strict rules and processes for every single step, and have to record everything that happens in a lab to make sure the experiment is reproducible by someone else.
These scientists are the ones who can analyse and manipulate cells and find out about how drugs work at a cellular level. This is science that forms the foundation for a lot of what we know about health and disease today, but is only part of the picture. A lot of studies published by these scientists are taken as proof of effects in humans. This is a huge and problematic jump to make.
Just because a chemical or drug or food makes a dramatic difference to cells in vitro (in a lab culture), it does not automatically mean the same effect will be seen in vivo (in a live animal). It may do nothing at all, something completely different or could even be harmful, because there are hundreds of processes that take place to carry that drug/food from mouth to cell. That is why in vivo studies are always needed.
Under control
Animal studies follow when a plausible explanation of how something works is announced by lab results. Scientists can investigate how that possible effect seen in vitro (in cells) translates into mice, rats and house flies, for example. This is where the magic happens for a lot of nutrition science, as we can control these animals’ environments in a way that we can’t do for humans. For example, it was thanks to an experiment in germ-free mice that scientists discovered the direct impact the gut microbiome has on depression. Often, complementary in vitro and in vivo results are reported together to provide the full picture.
People power
The second group of scientists works on answering human-related questions. Human studies are more complicated to run and more complex to interpret, because it’s impossible to keep people in the same environment for very long periods. This means human studies are usually either short-lived, such as in a randomised controlled trial, or they have to account for many factors that impact people over time. These factors can be individual, such as age, sex and ethnicity, lifestyle habits li
