Mar 5, 2014 10:22 PM by Connie Murphy
New research claiming that a double cheeseburger might be as risky as lighting up a cigarette may have caused protein lovers to choke on their milkshakes. Relax. Despite the ominous-sounding conclusion that too much dietary protein raises the risk of dying of cancer in middle age, there's actually very little valid information to back up the findings.
Some of the new research is consistent with the current thinking that diets high in animal fats can increase chronic disease risk, and that long-term consumption of a plant-based diet can reduce the risk of chronic illness and death. The other conclusions are only theories, not fact.
By combining epidemiologic data in humans, preliminary mice studies, and laboratory cell studies, the University of Southern California researchers have "connected the dots" in a convoluted series of explanations which do not hang together as an evidence-based concept. The report, which was published earlier this week in Cell Metabolism, attempts to find a cause-and-effect relationship of dietary protein and cancer risk, but fails.
"The comparison with smoking is really unwarranted in terms of the relative risks and the certainty of the adverse effects of smoking," says Tom Sanders, head of the Nutritional Sciences Research Division, King's College London.
Examining the well-studied NHANES database reveals further limitations with the study's conclusions. The number of people selected from this very large database was relatively small - an estimated 6,000 - and almost no important descriptive information about the study group was provided other than their age and self-reported protein intake from all sources. Factors like obesity and BMI, smoking status, and socioeconomic status were not accounted for and clearly impact all kinds of health risks.
While the dietary protein intake was self-reported, there was no distinction between animal proteins that are healthy (fish or skinless chicken) or those containing high amounts of saturated fats (fatty red meats). This is a major concern, and limits the conclusions of the results.
"Sending out statements such as this can damage the effectiveness of important public health messages," says nutrition scientist Gunter Kuhnle of the University of Reading. "They can help to prevent sound health advice from getting through to the general public."
Rather than be alarmed over protein, the takeaway should be: a diet containing high quality proteins, rich in fruits and vegetables, with a focus on plant-based eating is recommended and supported by science.