evidence pyramid, science, food blog, nutrition

Understanding Scientific Articles: 4 Questions You Need to Ask to Make Science Easy & Keep Your Health

 

Many a hundred of scientific articles get published in (bio)medical journals each year. Some of them about disease, some of them about prevention, and some of them about health and nutrition. Only a tiny miniscule proportion of those get portrait correctly in the media, and lots of times you will find yourself being misinformed, while you actually want to know what’s going on.

With the following tips, you can decipher any (bio)medical article, find out which ones apply to you and easily know which ones to discard. The four questions you need to ask are:

  1. What is the population studied?
  2. Has the study been carried out in cells, animals or humans?
  3. Where is the study on the evidence pyramid?
  4. Is the study relevant and applicable to you?

You can use this post over and over, as you find articles online or read the news about scientific discoveries related to health, to understand the basics of the science behind it.

Let’s start!

Question 1 | What is the population studied?

When reading scientific articles for your own health, there is one questions you must always ask yourself: “is the population studied in this study representative of me?”

For example, if you are a 60 year old African American man, the findings from a study carried out in 20 year old Swedish women might not be of any value for you. However, if you are a 25 year old Dutch woman, then the study in Swedish 20 year old women is perfectly comparable.

In other words, always ask yourself: are the conclusions found in this study also applicable to someone like you? This type of information about basic characteristics of the population studied is contained in Table 1 of every scientific article.

You can also use this checklist (if you are a man, just substitute woman for man) :

  • Has the study been carried out in women (or men)? If not, see below “has the study been carried out in cells or animals”.
  • If it has been carried out in women, were those women your own age? Or, were these children/girls, or adults, or even elderly (or centerians)?
  • (skip this step if man) If the study was carried out in women, were they premenopausal or postmenopausal? Hormone status of premonapusal women is very different to postmenopausal women, so these two groups might not be comparable.
  • Also, were they in health comparable to yours? Did they have certain chronic diseases?
  • Do they come from a specific population (such as Caucasian, Hindustani, African American, or even rural parts of Latin America) different to your own or are they comparable to you? Example, Swedish and Dutch populations are comparable, Swedish and African American not so much.

If the population studied does not match you in most of the above steps, then it is not representative of you. Hence, you might want to doubt the validity of it for you and think twice before applying the same methods for your health (it might just be a waste of your time).

 

Question 2 | Is the study carried out in cells, animals or humans?

When scientists observe something in humans but they don’t understand how/why this is happening, they often study the mechanism behind it in cells or animals. That is why you might often see the words in vitro and in vivo used in scientific or news articles.

An in vitro study is carried out cells or tissues whereas an in vivo study is carried out in animals (theoretically this term can also be used for studies in humans). In general, a study in vivo is more relevant than a study in vitro, but both of these need to be taken with a grain of salt.

As a human, the best evidence you can rely on for your health is that from human studies.

What if there is no evidence in humans, but only in cells or animals? If the only evidence for something ‘being benefitial’ is coming from cell or animal studies, you might want to think twice before immediately introducing it in your life. It might bring you harm, it might not be applicable in humans at all, or it just might cost you a lot of money (eg. supplements) without any real benefits.

 

Question 3 | Where is the study on the evidence pyramid?

An evidence pyramid is something that clinical scientists use all the time to belittle fundamental scientists, because it’s a tool that clearly states that clinical evidence is more relevant than animal studies, haha.

However, it also shows that large clinical studies are more valuable than a study on a single or just a couple of patients, and it shows that systematic reviews and meta-analysis, aside from randomized controlled trials, are the best evidence we have.

evidence pyramid, science, food blog, nutrition
The evidence pyramid: the higher the study on the evidence pyramid, the more seriously you can take its findings.
Source: http://library.downstate.edu/EBM2/2100.htm

Here’s an example: if I hear that someone’s cousin tried Spirulina and got glowing skin (this can be considered a “Case Report” or even an “Opinion/anecdote”) I might be tempted to try this too. However, if I really wanted to know whether this was evidence based, I would google “randomized controlled trial spirulina skin” (Google link to this search), to see if really, when you have a study where half the people use spirulina and the other half don’t, after a certain amount of time of a certain dose, the ones who use spirulina clearly have better skin. Now that would be strong evidence for me to start using it, much stronger in any case than the story of someone’s cousin.

How do you find out what type of study you are dealing with? This information should be in the Methods section or the title of the scientific article, it is called the study design and you should be able to easily compare it to the pyramid above.

 

Question 4| Is the study relevant and applicable?

This last question is all about the practicality of the study. You hear all the time about studies showing that factorX increases your risk of Somehorribledisease by 5%. Scary, right?

When you read something like that, you can always ask this one question: “what was the original risk, and what is the increased risk?”

The answer might be: the risk of Somehorribledisease is 0.1% in the general population, and with factorX the risk increases by 5%. So, if you have factorX, your risk of getting Somehorribledisease is 0.105%, which is actually still pretty low.

So, if there is a very small increase in risk, or if the risk was very small to begin with, you might think twice before applying the method in your own life for your own health. It might just be a waste of time.

At the same time, some studies show that you can decrease risk of a certain disease. There are many examples of interventions for decreasing risks (vitamins, exercise, medical drugs, supplements, etc). Let’s take the example of olive oil.

A study might show that olive oil is good for you. But, when you look at the practicality of it – maybe the study shows that people who consumed 0.5L of olive oil per day were healthier. This means you would have to consume 0.5L of olive oil per day to get the same effect. This might not be practical for you.

The same goes for supplements, where daily intake of supplements might bring about a small benefitial effect if the supplements are taken for years. This might not be the kind of money you want to spend on supplements (some supplements cost 300 euro per month, costing you thousands of euros for use longer than a year), or wasting if you know you won’t get around to using the supplements in exaclty the same way they were used in the study.

Just because a study showed something is good, does not mean it is relevant, pratical or applicable for you. Keeping this in mind can be good for your health and your wallet!

——

Using these four questions, you can now understand the basics of any (bio)medical scientific article. Also, you can immeditaley recognise whether the findings from the article are something you apply in your own life for your own health, or whether you should think twice before doing so.

Hope you enjoyed the post and please leave a message in the comments if you want to say hello!

 

Happy science-ing,

Ana, MD MSc

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