When it comes to nutritional science, headlines often make bold claims, but the devil is in the detail. A recent study has made waves by suggesting that red meat consumption might be linked to an increased risk of Type 2 Diabetes (T2D). But before you ditch that steak, let's look at some of the study's rather alarming weaknesses which are, unfortunately, all too common in nutritional science (more examples here).
Meat Contains No Glucose!
The claim that red meat is linked to diabetes makes no sense from the outset, as diabetes is a glucose handling issue and meat contains no glucose! It would clearly be more obvious to suspect the buns, fries and soft drinks that burgers are consumed with.
Self-Reported Dietary Data
The study relied on participants to recall and report their dietary habits through Food Frequency Questionnaires (FFQs). Such self-reported data can be subject to recall bias (where participants may not accurately remember their food intake) and reporting bias (where participants may deliberately or inadvertently misreport their food intake). Imagine trying to remember exactly how many times you ate a specific food in the past year!
This is very different from, say, self reporting on smoking habits. For example, asking "what brand do you smoke and how many do you have per day?" is about the extent of the questioning required and will be very accurate.
The study defined unprocessed red meat as including hamburgers and sandwiches. When we talk about hamburgers or sandwiches, what kind of bread is used? What oils or other additives might be involved? Was the meat grass-fed or grain-fed? What sauces did they use? Were they high in sugar? Was the meat cooked at high temperatures or chargrilled, thus containing high AGEs? Hamburgers also tend to be eaten with fried chips and soft drink. By lumping these into the "unprocessed" category, the study overlooks many other potential factors.
Participants with higher red meat intake also had higher Body Mass Indexes (BMIs), smoked more, and were less active- strong risk factors for developing TD2. Many participants were medical professionals who, due to the nature of their jobs, lead lifestyles involving shift work, heightened stress, and disrupted circadian rhythms – all factors independently linked to T2D. It's a classic case of correlation, not necessarily meaning causation.
BMI's Big Role
When the study took BMI into account, the link between red meat and diabetes risk weakened substantially. This suggests that weight might play a more significant role in diabetes development than red meat intake. Moreover, it’s ridiculous to say that red meat caused high BMI when the main weight gain culprits, such as soda drinks and sweets, weren’t assessed. We doubt eating 85g of lean grass-fed and grass-finished steak would make anyone overweight.
When researchers adjusted the results using "dietary calibration," the risks associated with red meat consumption shot up. This raises eyebrows. If the initial method is solid, why would calibration produce such drastically different results?
To explain, calibration in the study aimed to correct dietary assessment errors by comparing food frequency questionnaires to 7-day weighed diet records. However, this method assumes consistent error relationships across the study population, and using a subset for calibration might not represent the broader group, possibly introducing biases. While calibration seeks to enhance accuracy, it can also add complexity and potential inaccuracies to the study's findings.
The risk of T2D was mainly associated with red meat intake assessed within the last 12 years, not at the study's start. This raises the question: If red meat were a significant risk factor, wouldn't its impact be consistent over time?
Other Dietary Factors
The study didn't look deep into other dietary habits. If someone eats red meat frequently, what foods do they potentially eat less of? Salads? Fruits? The role of what's missing from the diet is just as important as what's included. Furthermore, the study did not analyse the intake of ultra-processed junk foods, sweets, and soda drinks, which would be the highest dietary factor contributing to diabetes.
Nutrition science is complex, and while red meat might be an easy target, the broader picture is far more nuanced. As with most things, moderation is key, and an active lifestyle and balanced diet free from ultra-processed foods remain the golden recipe for health. Saying that eating good quality meat will cause Type 2 Diabetes is absurd.
Find out What’s The Healthiest Way To Eat Red Meat.