We’ve said it before and we’ll say it again: Eating a diet high in protein will not kill you. Yes, a recent study said it could, but it was incredibly misleading. Here’s why.
In the study, published recently in the journal Cell Metabolism, researchers examined data from the third National Health and Nutrition Examination Survey, a massive suite of surveys recording the health and nutrition habits of Americans, and reported that eating a low-protein diet when between the ages of 50 and 65 decreases overall mortality, cancer mortality and diabetes mortality. Conversely, once you reach the grand old age of 66, they found that you’re free to eat a high-protein diet to prevent frailty.
Confused? You should be. Not only is there not much difference between the ways a 65-year-old body and a 66-year-old body process protein, but the data used in this study was flawed. The study asked participants to report what they had eaten the previous day and then assumed that that one day's meals were indicative of how the subjects ate over the next 18 years.
And that’s the data that the researchers used to say that those subjects who fell into the “high-protein” group were 75 percent more likely to have died over the following 18 years when compared with those who reported eating a lower-protein diet.
At fault, according to the researchers, are higher levels of insulin-like growth factor-1 (a compound involved in tissue growth) in those who eat more protein, which they claim enhances the growth of tumors, leading to increased death from cancer. To test that hypothesis, the scientists even did some studies in mice that already had cancer and found that higher IGF-1 levels did indeed increase the growth of tumors. The keywords there are already had cancer. Nowhere in their research did this study’s authors find evidence that higher protein intake causes cancer.
Furthermore, there was no data collected about the types of protein that the folks in the higher-protein group ate. (Was it lean beef, poultry and fatty fish? Doubtful.) There was also no data about what else they ate — or how much. Buckets of fast-digesting carbs? That certainly would have accounted for the increases in diabetes that researchers reported. And were the subjects exercising regularly? We don’t know because that data wasn’t reported either.
Ultimately, the results of this study shouldn’t influence how you eat — or how your parents or grandparents are eating. Chalk it up to yet another misguided attempt to diagnose the problems our society has with food. Just remember: A diet high in lean sources of protein and low in fast-digesting or processed carbohydrates certainly won’t harm a healthy, active individual of any age. — Jordana Brown