Should I be vegan? Should I be paleo? Should I follow low fat? Should I follow low carb? Does this cause cancer? Does that protect against heart disease? Should I worry about my cholesterol? … What does the research say?
I’ve been wanting to write this post for a while, mostly because someone asks me at least once a week – “doesn’t research show that (insert food here) causes (insert chronic disease here)?”
“But won’t eating eggs every morning increase my cholesterol?”
“Won’t putting salt on my food raise my blood pressure?”
Why is there so much conflicting information?!
One thing we must consider is that nutrition research is ALWAYS changing. What was “right” 5 years ago could be absolutely not “right” today. We have to put a different cap on when thinking about nutrition. 2+2 is always going to equal 4 (hopefully) but a particular food may not always be labelled as “unhealthy” according to experts.
Over the past few years, I’ve gained a new appreciation for nutrition research. I’ve realized that just because the research does not prove that a food or chemical is harmful (*cough* aspartame/sucralose/etc.) does NOT mean that we should consume it on a regular basis. And just because there isn’t enough evidence to rule out something we should not be using in foods (*cough* artificial colours) does not mean that it’s okay.
I’ve also learned that there are flaws in many nutrition research studies (and not at the fault of the researcher.. it is just the nature of how the study must be conducted).
To explain my point better, let’s look at how many nutrition studies are conducted (simplified of course):
- A group of people are randomly selected and are given a food frequency questionnaire to determine how frequently a person eats a particular food (see example below).
- Whether or not a person has or will develop a chronic disease is also noted.
BOOM – Research shows that increased french fry consumption is linked to increase risk of developing arthritis.
So what’s the problem?
I work with people who journal their food and I can guarantee you that 9 out of 10 people cannot even remember what they had for lunch two days ago let alone how many times they’ve consumed red meat in the last 3 months.
I am picking on the red meat and cancer association because this is the one that I hear most often.
When looking at associations like red meat and cancer we also have to think of other aspects that may impact the results: food quality and cooking method. … Now things get a little more complex.
If I were to ask you: How many times in the last month have you consumed red meat and how did you prepare it and where did the meat come from… would you have an accurate answer? Likely not.
So why can’t we just do better research?
The best way to do research would be to take a large subject group, feed half of them one particular way and the other half another way. We would then monitor them over a 50 year period and see who develops what disease. During this time we would also have to control environmental factors that could impact the results: stress, exposure to environmental toxins, physical activity and sleep. Easy, right!?
A study like this is not only unethical (because feeding someone a diet full of “foods” that researchers suspect to lead to chronic disease development is unethical. But good luck getting people to sign up for this study and good luck controlling for all of these variables.
What I am trying to say is that researchers are doing the best they can with what they have to work with. The nature of nutrition research just makes it extremely difficult to determine cause and effect.
Another issue is subject bias – “Subject bias, also known as participant bias, is a tendency of participants (subjects) in an experiment to consciously or subconsciously act in a way that they think the experimenter/researcher wants them to act. It often occurs when subjects realize or know the purpose of the study” (thank you, Wikipedia).
So how can this play a role? Well, if I have cancer and type 2 diabetes and I am filling out a food frequency questionnaire that I suspect is trying to prove that poor diet leads to various chronic diseases, I may be more likely to recall that I consume the “bad” foods more often. This isn’t necessarily because I actually do, but because I know that this is what researchers are trying to find.
I am not a psychologist (although sometimes I feel like it 😉 ) so I can’t tell you exactly why this happens… I can just tell you that it does :).
I pride my practice on being research-based but let’s be real, nutrition research is ALWAYS changing and there is ALWAYS going to be conflicting evidence. I take previous client experiences into consideration when making recommendations and having worked with such a large number of clients over the years I definitely see patterns that other health professionals may say is “not supported by research” (i.e. gluten sensitivity – sorry, but I see this EVERYDAY!)
I could dive in deeper about issues with researchers often “seeing” what they want to see in the research (i.e. researchers supporting a vegan diet often find that vegan diets are the best for our health, etc.) but let’s just leave it at that.
The main thing I want you to take away from today’s post is that when your co-worker, sister, cousin, neighbour, etc. comments on your food or tells you that a particular food reduces or causes a particular condition… take it with a grain of salt (literally, salt your food, it’s OKAY). The most important thing is that you are eating in a way that makes YOU feel good, regardless of what the evidence says.
What are the most confusing nutrition topics you hear about today? Post them in the comments below
Yours in Health,