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What is evidenced-based nutriton?

Updated: Dec 9, 2021

Choosing the right nutritionist can be difficult, but finding one you can trust shouldn't be. Despite thinking that using evidence for practice should be a standard in the industry, this in many instances isn't the case. So the question is, what is an evidence based nutritionist and how do you spot one?




I guess the first place to start is why people mislead others. Honesty and the use of evidence should be a standard thing but is not often the case. People's own experiences of nutrition can be powerful but also misleading. Often you'll hear people saying how cutting out gluten or dairy has had a drastic impact on health or weight loss o of overall health and that becomes a universal truth for them. However, what they often overlook is the overall impact that has had on their overall dietary patterns or other lifestyle changes made alongside it. However in the face of evidence and challenging their beliefs they often circle back to personal experiences over the body of evidence.


Then on the other hand you have the charlatans, people who should know better but are straight up trying to deceive others. They often present themselves as experts but there's nearly always a telltale signs that give them away. They often present themselves as individuals who know all the secrets that nobody is talking about- outsiders who know the truth that claim that the body of evidence is trying to silence them. They often talk a lot about hormone imbalances, resetting metabolisms and detoxes. They speak in absolutisms about their methods. Then comes the sales pitch- buy X and Y supplements: ketones, fat burners, herbs and watch your ailments disappear. Sadly too many people, particularly yo-yo dieters are sold the idea of the quick fix miracle cure and spends small fortunes on products they don't need.


So, how can we avoid these people and find the evidence based nutritionist offering sound advice?


I guess what sets us apart is the ability to make assertions with evidence to back it up with a good body of evidence. But even this can be misleading as you see so many confusing headlines in newspapers and magazines that often contradict themselves. So what makes good or bad evidence?


At the lower end of the scale in terms of evidence quality, we have studies done in test tubes or in animals. They aren't completely useless- they just don't immediately transfer into showing a direct impact on a human body because a) your more complex than a few cells in a test tube an b) you're not a mouse/rat.


Next up the chain we have observational studies. These often look at larger populations at the present time or retrospectively. Whilst you can see trends in populations they can sometimes be misleading. Why? Because you can't control every factor in someones life to say with certainty that x causes y. And when looking back at things retrospectively, people's memories of things can come into question.


Then we have lab studies in humans. These can be great because you can control a lot more of a person's environment, compare to a placebo and measure result a lot more accurately. However, when we look at the results we still need to take into consideration things like sample size, repeatability of those results and how long the study took.


To help make sense of all the different lab studies done in similar areas and help make sense of all these individual studies, systematic reviews and meta-analysis papers can help paint a great overall picture. They aren't perfect- you could clump bad studies together and end up with a bad conclusion but a well researched meta-analysis is the closest we can get to certainty on a given dietary subject.


So if you do get confused by a headline or an assertion by someone who can't offer good evidence then chances are it's just an opinion. If there's anything you've seen and want to ask a question or looking for an evidence based practitioner in Cardiff, about my inbox is always open.






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