You may have heard the latest. Yesterday it was reported that a new studyshows a positive correlation between eating red meat and dying an early death. Gasp!!
“Scientists warm ‘red meat can be lethal’”
“Red meat is blamed for one in 10 early deaths”
And from our very own Sydney Morning Herald: “Study finds red alert on eating meat”
There are some pretty dramatic headlines being bandied about.
But, does this study actually prove that eating red meat will do us damage? Really???
Let’s take a closer look.
Firstly, the study in question is a plain old retrospective observational study, not an actual conclusive experiment with controls and manipulated variables. It can’t actually claim to provide evidence of anything. This particular type of investigation lies at the bottom of the scientific study food chain when it comes to reliability (especially in the field of Nutrition).
Secondly, all the information portrayed in this observational study came from dietary data collected via what’s known as ‘Food Frequency Questionnaires’ (FFQs), where participants filled out information about their average yearly (yes, yearly) food intake… once every four years.
Ding, ding, ding! At this point, alarm bells are already ringing. Four years??! Some days, I can barely remember what I ate for breakfast that morning, and I have a professional interest in the matter! There is no way on earth that I would have a clue what’s passed by my lips for the last four years!
But hey, let’s not write it off just yet. Perhaps some people have a freakishly accurate memory. Let’s take a look at the actual questionnaire, shall we? (it’s available online for you to follow along if you like).
Here’s a sampler of the ‘meats’ section, where participants are directed, “For each food listed, fill in the circle indicating how often, on average, you have used the amount specified during the past year.”
“Red meat is blamed for one in 10 early deaths”
And from our very own Sydney Morning Herald: “Study finds red alert on eating meat”
There are some pretty dramatic headlines being bandied about.
But, does this study actually prove that eating red meat will do us damage? Really???
Let’s take a closer look.
Firstly, the study in question is a plain old retrospective observational study, not an actual conclusive experiment with controls and manipulated variables. It can’t actually claim to provide evidence of anything. This particular type of investigation lies at the bottom of the scientific study food chain when it comes to reliability (especially in the field of Nutrition).
Secondly, all the information portrayed in this observational study came from dietary data collected via what’s known as ‘Food Frequency Questionnaires’ (FFQs), where participants filled out information about their average yearly (yes, yearly) food intake… once every four years.
Ding, ding, ding! At this point, alarm bells are already ringing. Four years??! Some days, I can barely remember what I ate for breakfast that morning, and I have a professional interest in the matter! There is no way on earth that I would have a clue what’s passed by my lips for the last four years!
But hey, let’s not write it off just yet. Perhaps some people have a freakishly accurate memory. Let’s take a look at the actual questionnaire, shall we? (it’s available online for you to follow along if you like).
Here’s a sampler of the ‘meats’ section, where participants are directed, “For each food listed, fill in the circle indicating how often, on average, you have used the amount specified during the past year.”
Let’s see. Why are whole, natural foods such as eggs, fish and meats lumped in with hot dogs, bologna sandwiches and hamburgers??! I would argue that even individual types of whole foods ‘meats’ need to be accounted for separately (ie chicken, white fish, red fish, eggs, beef), yet all these results are tallied within the same category. Heck, I would even say that for the study to provide any legitimate results, you’d have to go even further and differentiate, say, your organic, free-range chicken eggs from your soy-fed cage eggs, and your grass-fed-and-finished beef from your stock standard grain-fed – they might look the same, but they’ve got completely different nutritional profiles.
Now, let’s examine how ‘serving size’ is accounted for. “Hamburger (1 patty)” – how much is this? “Bacon (2 slices)” – if my general serving of bacon is actually 4 slices, am I really going to admit to this and call it a 2-times-a-day food if I’m only eating it for breakfast??
“Onions, as a vegetable, onion rings or soup” under ‘vegetables’, and “Pizza (2 slices)”and “French Fries (1 serving)” both under ‘breads, cereals, starches’. It just gets more and more infuriating!
Based on the questionnaire alone, this study should be tossed on the dumpheap. But if you’re still not convinced…
‘Food Frequency Questionnaires’ are notoriously inaccurate ways to collect dietary data. There have been whole studies devoted to proving just how unreliable they are.
“Foods underestimated by the FFQs compared with the diet records (ie, the gold standard) included processed meats, eggs, butter, high-fat dairy products, mayonnaise and creamy salad dressings, refined grains, and sweets and desserts, whereas most of the vegetable and fruit groups, nuts, high-energy and low-energy drinks, and condiments were overestimated by the FFQs.”
Source: The American Journal of Clinical Nutrition, Vol. 69, No. 2, 243-249, February 1999 (available online)
It would seem that there’s a lot of people out there overestimating their fruits and veg, and not ‘fessing up (perhaps unintentionally) to lots of processed foods, refined grains and sweets.
Both of these two published studies found evidence of precisely the same problem when it comes to the reliability of food frequency questionnaires.
“Mean daily amounts of each food calculated by the questionnaire and by the dietary record were also compared; the observed differences suggested that responses to the questionnaire tended to over-represent socially desirable foods.”
Source: The International Journal of Epidemiology, Vol. 18, Iss. 4, 858-867 (available online)
The glaring flaw is thus: people tend to report what they think they should be eating, not what they actually eat. And that’s before even taking into account that, in this case, they’re having to recall and remember an entire four years worth of food.
As a final hurrah, here’s the real kicker:
A table from the very same study in question (that is, the study bastardising one of the foods most vital in our evolutionary history). Look closely at some of the other things it shows. In short…
Participants who reported the highest meat intake, also:
1. Smoked the most
2. Did the least exercise
3. Took the least vitamin supplements
4. Drank the most alcohol
5. Had a trend towards less healthy (non-red meat) food choices (such as refined grains, processed foods and sugar)
6. Consumed the most calories overall
All these factors are described in the study. Yet, incredulously, somehow red meat took the final bullet. (???!!!)
Pity they didn’t choose to survey some health-conscious, omnivorous, meat-eating individuals – I know plenty.
****A side note: The participants who reported the highest meat intake also has thelowest cholesterol readings, whilst the meat-avoiders had the highest cholesterolreadings. Regardless of the invalid way in which the study was conducted, I sure wish they’d highlighted this finding instead!
That would be the absolute final nail in the coffin for this study, ladies and gents.
For the nutrition nerds: here’s a really geeky overview and utter demolition of the study by Zoe Harcombe.
The bottom line:
Basically, even the most ridiculously invalid ‘findings’ can be spun out by the media and sensationalized in a way that promotes an entirely unfounded idea with zero scientific evidence to back it up. It’s completely out of control, yet people swallow this nonsense as truth. Please, be critical and question what you read, especially when it comes to health!!!
Now, let’s examine how ‘serving size’ is accounted for. “Hamburger (1 patty)” – how much is this? “Bacon (2 slices)” – if my general serving of bacon is actually 4 slices, am I really going to admit to this and call it a 2-times-a-day food if I’m only eating it for breakfast??
“Onions, as a vegetable, onion rings or soup” under ‘vegetables’, and “Pizza (2 slices)”and “French Fries (1 serving)” both under ‘breads, cereals, starches’. It just gets more and more infuriating!
Based on the questionnaire alone, this study should be tossed on the dumpheap. But if you’re still not convinced…
‘Food Frequency Questionnaires’ are notoriously inaccurate ways to collect dietary data. There have been whole studies devoted to proving just how unreliable they are.
“Foods underestimated by the FFQs compared with the diet records (ie, the gold standard) included processed meats, eggs, butter, high-fat dairy products, mayonnaise and creamy salad dressings, refined grains, and sweets and desserts, whereas most of the vegetable and fruit groups, nuts, high-energy and low-energy drinks, and condiments were overestimated by the FFQs.”
Source: The American Journal of Clinical Nutrition, Vol. 69, No. 2, 243-249, February 1999 (available online)
It would seem that there’s a lot of people out there overestimating their fruits and veg, and not ‘fessing up (perhaps unintentionally) to lots of processed foods, refined grains and sweets.
Both of these two published studies found evidence of precisely the same problem when it comes to the reliability of food frequency questionnaires.
“Mean daily amounts of each food calculated by the questionnaire and by the dietary record were also compared; the observed differences suggested that responses to the questionnaire tended to over-represent socially desirable foods.”
Source: The International Journal of Epidemiology, Vol. 18, Iss. 4, 858-867 (available online)
The glaring flaw is thus: people tend to report what they think they should be eating, not what they actually eat. And that’s before even taking into account that, in this case, they’re having to recall and remember an entire four years worth of food.
As a final hurrah, here’s the real kicker:
A table from the very same study in question (that is, the study bastardising one of the foods most vital in our evolutionary history). Look closely at some of the other things it shows. In short…
Participants who reported the highest meat intake, also:
1. Smoked the most
2. Did the least exercise
3. Took the least vitamin supplements
4. Drank the most alcohol
5. Had a trend towards less healthy (non-red meat) food choices (such as refined grains, processed foods and sugar)
6. Consumed the most calories overall
All these factors are described in the study. Yet, incredulously, somehow red meat took the final bullet. (???!!!)
Pity they didn’t choose to survey some health-conscious, omnivorous, meat-eating individuals – I know plenty.
****A side note: The participants who reported the highest meat intake also has thelowest cholesterol readings, whilst the meat-avoiders had the highest cholesterolreadings. Regardless of the invalid way in which the study was conducted, I sure wish they’d highlighted this finding instead!
That would be the absolute final nail in the coffin for this study, ladies and gents.
For the nutrition nerds: here’s a really geeky overview and utter demolition of the study by Zoe Harcombe.
The bottom line:
Basically, even the most ridiculously invalid ‘findings’ can be spun out by the media and sensationalized in a way that promotes an entirely unfounded idea with zero scientific evidence to back it up. It’s completely out of control, yet people swallow this nonsense as truth. Please, be critical and question what you read, especially when it comes to health!!!
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