Hello and welcome to this understanding nutrition science segment where today we're going to be focusing on the grade

system of evaluating evidence grade stands for the grading of recommendations assessment development

and evaluations and while not specific to nutrition science necessarily, the application of the grade framework

to assess the certainty or quality of evidence has posed issues for the interpretation of nutrition

research, particularly in relation to epidemiology and the findings from cohort studies.

We'll specifically talk about the concept of effect sizes and how systems like grade which are born out of the biomedical model,

in effect by default bias the findings from nutrition research towards being

rated as low certainty and quality evidence overall. So, first off, what is grade?

Grade is a framework that was developed for presenting a summary of evidence as part of

informing clinical practice recommendations. And in the biomedical world, grade has become the

most widely adopted tool for the grading of the quality of evidence.

Like many issues that pertain to nutrition science methodology, the difficulty is we have the

application of a framework with grade that has largely been developed to consider evidence either from

epidemiological exposures in a biomedical hazard context, for example, the risk of smoking

cigarettes and any cancer or cardiovascular related outcomes. And the difficulty with this application as well is posed in relation to randomised control trials

because of the use of this system to rate trials based on biomedical criteria.

But where the friction arises for nutrition research is primarily in relation to epidemiology and prospective cohort study outcomes, which will be much of our focus of today's segment.

So how does grade work and what is the process of evaluation? Like a systematic review or indeed a meta-analysis,

usually the grade system will look to a specific research question. For example, what is the

evidence for the consumption of soy products and breast cancer risk? Or what is the evidence

for the consumption of red meat products

and colorectal cancer risk? So it starts with that particular research question and the

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