A new evaluation of randomized studies shows that eating red meat, on average, improves blood glucose and markers of insulin sensitivity, with no significant effect on inflammation.
For those following a low-carb diet without restricting red meat, these findings likely come as no surprise. But what makes this study remarkable is that the authors state in their introduction that "we hypothesized that higher total red meat intake would negatively influence glycemic control and inflammation..."
I applaud the authors for making their assumptions clear, and for acknowledging that the results proved those assumptions wrong. This discrepancy between hypothesis and conclusion highlights the importance of testing hypotheses and testing findings from observational studies.
As we have detailed before, many nutritional observation studies provide low-quality data and are not reliable for drawing conclusions. Some of these observational studies have shown an association between eating red meat and the risk of type 2 diabetes. That has led many to believe red meat causes diabetes. But this is an inappropriate interpretation of the data.
Instead, we need to know if randomized controlled trials, a higher level of evidence, confirm the observational findings. The data should inform beliefs, not the other way around.
This new meta-analysis compiles 24 randomized trials of adults without pre-existing cardiometabolic disease. It included trials lasting up to 16 weeks, with an average of eight weeks. Since these were all randomized intervention trials, they eliminate many of the problems commonly seen with observational studies, such as healthy user bias, poor food recall, and uncontrolled confounding variables.
Keep in mind that the compiled studies were not specifically focused on low-carb diets. They simply evaluated the impact of red meat intake with similar baselines diets (which varied from study to study).
The findings correlate well with what low-carb clinicians often see in their patients and what findings from low-carb studies show. Low-carb diets without restriction on red meat can help treat and reverse type 2 diabetes, improve insulin resistance, and treat metabolic syndrome.
While the current study showed no effect, positive or negative, on inflammatory markers, some low-carb studies show inflammatory improvements.
What does this all mean for you?
It comes back to one of our underlying messages at Diet Doctor. It isn't enough to rely on one study, especially a nutritional observational study, to shape our conclusions. Instead, we need to incorporate higher quality evidence and understand the strengths and weaknesses of different studies.
We will continue to be a source of reliable health information that cuts through the hyperbole and helps make sense of the science.
Thanks for reading,
Bret Scher, MD FACC
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