It is my intention going forward to look at nutrition and individual types of cancer. In order to do this, I rely on good quality research so that the information is as accurate as possible.
I do know that many of you also look at research and as a result many of you get confused by conflicting evidence and mixed messages.
For this reason, I thought that this month it would be a really good idea to look at the types of research that are around and which is the most reliable and how to interpret the results that you read.
As you can imagine, nutrition is forever changing as new things are discovered and it is part of my job to keep abreast with the changes. When I did my degree in Nutritional Medicine a lot of the work was training to be selective about what we read and to make sure that the information was from a reliable source. I came across this good article that explains the different types of research available and what it means to us, so I wanted to share this with you so that you too can be discerning about what information you take on and which you discard.
The article is called the ‘Hierarchy of Nutritional Evidence’, written by a nutritional consultant Dr. Emma Derbyshire. I have summarised the article for ease of reading.
Type of study 1. Systematic Reviews (the gold standard) are articles or studies that pool together the results of loads of the best quality trials and examine them to see if they can find a consistent pattern.
What this means; A clear unbiased overview of the best available information we have so far: reviewing loads of studies helps detect and eliminate any red herrings.
As the hallmark of good science is reproducibility, these reviews are about as rigorous as they get.
2. Clinical Trials serve people a regular dose of a specific food/compound in a carefully controlled setting and see if it affects their health.
Some trials are far more carefully controlled than others, meaning their results are more reliable. What this means; The more people in a study, the more reliable its findings are likely to be, which helps iron out any fluke results.
For this reason, it is important to look at not only a clinical study’s findings but also its methods. If a study has intriguing results but only tested on a small number of people then more research would be needed to make the results useful.
3. Observational studies carefully track the habits of a large population of people to see if there are associations between eating certain foods and certain health outcomes.
What this means; The ‘Achilles heel’, of these studies is that they can only show associations, not actually prove cause and effect. Correlation does not equal causation. However, they can be useful as a general guide. It is from this type of study that the Mediterranean diet was born and recommended.
4. Animal studies give lab animals a regular dose of a food and measure the effects on their health
What this means; these studies can be a really useful tool to identify promising ideas but they have a simple flaw. Humans aren’t lab animals. This means that the results are not replicable when you run the same experiment in people. In fact, as few as 30% of the findings of animals and test tube studies are later reflected in human subjects.
They can still point out some useful clues but not to be used as categorical evidence.
5. Test Tube studies apply extracts of food to isolated cells or chemical models of parts of the human body and see what the results are.
What this means; We are further removed from blobs of cultured cells in a petri dish than we are from animals in a lab. As one dietitian put it. ‘what happens in the test tube stays in the test tube’. Useful as a first step to find initial tip offs, but far far away from conclusive evidence.
As you can see there is a clear hierarchy of trials. So, when you are reading information always make a point of looking to see what type of trial it was and who it was carried out by. This way you can draw your own conclusions about its potential to be useful. Not always easy.
Next month I will draw on my research and outline the recommended type of eating programme or diet to follow if you have cancer or are post treatment. I hope that you have found this blog useful.
Blog originally written by Caroline June 2017 - checked April 2021