“If these two studies are really correct, what people in general are trying to do might be completely wrong in terms of maintaining health and even longevity.” – Shin-ichiro Imai, MD, PhD, of Washington University
A few weeks ago, two studies were published in Cell Metabolism which generated huge press coverage but little true scientific discussion. Both studies concerned the effect of the ratio of dietary protein to carbohydrate on health and longevity.
In the first study, 858 mice (C57BL/6) were fed 25 different diets ad libitum, the composition having various protein, carbohydrate and fat levels. With 34 mice per treatment arm, those on the low-protein, high-carbohydrate diet lived the longest … and were the fattest.
In the second study, the 24-hour dietary record from 6,381 adults collected two decades ago as part of the NHANES III were analyzed and matched with subsequent mortality data. Their conclusion: in those under 65 years old, a high-protein intake increased all-cause mortality 74 percent while in those over 65, it resulted in a 23 percent reduction in all-cause mortality!
I have no idea what to do with this data, and neither does anyone else, as they are nothing more than small observations that fly in the face of years of experience and teaching, leaving physicians skeptical. However, there is no shortage of pundits reporting the data as though they do know what it means and, further, what strategies we should be employing based on these results. The authors both concluded, to their credit, simply that more data was needed.
In 1981, an analogous “stir” was produced when the Harvard School of Public Health reported in the New England Journal of Medicine that coffee consumption was associated with pancreatic cancer, that study based on interviews with 369 patients and 644 controls. Again, the result seemed contrary to experience. The uproar among the lay public was deafening while most medical thinkers took a “wait and see” approach, the authors concluding more data was needed. Thankfully, for all of us who are coffee drinkers, the association has not born the test of time.
In an analogous fashion, if we consider the nouveau clinical and economic proposals being inflicted on medicine today, how many authoritarian pronouncements have been made, how many edicts set forth, how many directives issued as though they are “fact” when in truth “we don’t know what to do” and “we need more data”? After all, there is a history. As young interventionists, we dilated those coronaries we were told should be opened, later stenting those we were told should be stented, only now to be told that we were “wrong.” Our echocardiographers did annual echocardiograms as they were taught to do by the “experts” on their valvular and heart failure patients, only to now be told they were “wrong.” Our isotopists did repeated perfusion images on those with repaired coronary artery disease, being told they should evaluate their patients’ progressive ischemic burden, only now to be characterized, if they follow such a path, as overutilizers, exposing their patients to undue radiation, the efficacy of the very test itself now brought into question.
Yes, in both the clinical and business arenas of medicine, knowledge advances, the rules that shape our daily practice evolve and the paradigms we employ shift. But let no one imply that the failure of physicians to mindlessly embrace, as fact, the unproven sometimes radical changes proposed by others is somehow a unilateral failure of those skeptics to “see the truth.” Do not suggest those hesitant to embrace the unproven and untested have undergone some sort of ethical metamorphosis to a less-honorable, obstructionist state.
Perhaps they are just more wise, battle scarred and tempered in the fiery crucible of experience, having recall of remote, vaguely familiar, analogous proclamations that turned to folly, sometimes at great expense.
Maybe they, more than most, are fully aware that “we don’t know what we don’t know.”