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A recent study in Nutrients by researchers at the University of California, Davis, demonstrates robust performance, as compared to an array of biomarkers, of a novel dietary assessment method based on pattern recognition.
The method- diet quality photo navigation- which has passed other such tests, is the first fundamentally new way to assess dietary intake introduced in decades, requiring no recollection of details, no food logging, no need to take pictures. The approach can complete a genuinely comprehensive analysis of dietary intake - including operationally defined diet type, a validated measure of overall diet quality, and intake levels of all food groups and roughly 200 nutrients - via smartphone or other digital interface, in as little as 60 seconds.
You could know many of these particulars already because published papers say as much. I know them because…I invented this method, and founded the company that makes it available. Our corporate mission is to make diet quality a vital sign.
Can you begin to imagine the profound, irrepressible, transformative impacts – on public health, epidemiology, the standard of clinical care, and even the food supply - of treating diet quality as a vital sign? Perhaps not, because the proposition is so foreign to our native experience that imagination lacks even a toehold. (What’s that you say: you didn’t imagine that imagination had toes? Topic for another day…)
Diet quality, measured objectively, is the single leading predictor variable for all-cause mortality and total chronic disease risk in the modern world. As goes diet quality, so goes the probability of more or less years in life, more or less life in years. So go the prevalence and predation of obesity*, diabetes, heart disease, COVID, many cancers, stroke, dementia, disabling arthritis, and more. Diet quality is by no means the only thing that matters, of course, but it is the single thing at the population level that matters most.
A rather deplorable, generally unmeasured diet quality hides, and festers, in plain sight. That sad fact is revisited each time the “typical American Diet” is referenced with derision, lamentation, or exasperation. Famously, we don’t tend to manage what we fail to measure. Our failure to quantify the liabilities of diet in each of us is not the only reason we allow the problem and its dire consequences to persist, but it is salient among them.
Accordingly, our thought experiment: let’s imagine a world where this “single most important” measure were actually measured, routinely, in everyone. Diet quality is currently measured in almost no one (do you know yours, as you know your blood pressure?), and is not managed as either a routine clinical or public health imperative. Our thought experiment is immediately imperiled because the relevant appendages in our imaginations are atrophic, having never been nurtured nor nourished; the counterfactual world- where diet is a vital sign- is just too foreign.
We can get there another way, however. We know what a world is like in which another vital sign- c- actually is measured, and managed, routinely- because we live in such a world. We can imagine a world in which the blood pressure (BP) cuff had never been invented. That, too, should be within imaginary reach of us all, and all the more so of any medical historians in the mix, since we actually lived in such a world- before the BP cuff, or sphygmomanometer, was invented, and adopted into widespread use.
Of note, those two steps were truly distinct. When the device we know as a BP cuff was first invented, and even after some early refinements, the House of Medicine was largely resistant, channeling a blend of arrogance and traditionalism. The prevailing mindset in Medicine was apparently then, as now: if it were important, we would have been doing it already; if we aren’t doing it already, it can’t be too important.
For any patient who has encountered this toxic admixture in their dealings with the medical profession- my apologies, and condolences. To those of us in this club, let’s get over this nonsense, shall we? We, like every dynamic system from organism to organization must adapt or die. The adoption of worthy innovation is the very core of adaptation.
We knew a world before the BP cuff finally overcame all resistance, forever to alter and elevate the standard of care. What was that world like?
Stated bluntly, there was a ghastly toll of stroke, heart attack, and kidney failure that the routine measurement and management of blood pressure has been preventing ever since.
The importance of blood pressure was already well and widely known before the advent of the BP cuff, from a diversity of sources (just as the importance of diet quality is well and widely known today). The role of blood pressure aberrations in critical outcomes involving heart, brain, eyes, kidneys and more- was known, too, albeit less well than now. The established importance of blood pressure argued for its routine measurement and management before that was possible, but only its routine measurement established the full extent of its importance. There’s a lesson there, and a portent.
Blood pressure could be measured before introduction of the BP cuff, but only with difficulty, inconvenience, pain, cost, or some combination of these. Intra-arterial assessment of blood pressure is still a recourse in the ICU today, but only when rather extreme circumstances justify it. This method, though efficacious, is ill-suited to routine use.
The BP cuff replaced that suite of liabilities with their antonyms: ease, convenience, comfort, and economy. A much better way of getting at information already known to be crucial inevitably exerted a gravitational force: because we now could, the argument ensued all but ipso facto that we should. That “should” evolved into “must,” as the assessment of blood pressure insinuated itself into the standard of practice.
Routine assessment of blood pressure became, in turn, another transformative influence, as it amplified awareness of the epidemiology and consequences of hypertension. Over time, this induced an array of responses all now sufficiently commonplace to be taken for granted: effective treatments for hypertension spanning whole drug classes as well as lifestyle approaches; a fixed and mandatory field for blood pressure in every health record; the management of blood pressure as a quality control measure for providers, practices, and health systems; the articulation and evolution of specific treatment targets; and more.
Finally, and perhaps most fundamentally: the routine measurement of blood pressure became an authoritative cue to action. Knowing what blood pressure is, and contrasting that with what it ought to be, mandates a response whenever the two diverge. That requirement in turn forces accommodation upon the entire system of medicine: resources must be available so that every aberrant blood pressure entry is capably addressed. Those resources span drug development; medical school curricula; continuing medical education; specialization; referral; and, of course, reimbursement.
In short, we don’t merely “manage what we measure.” Rather, measurement and management are synergistic, iterative, auto-catalytic elements in a positive feedback loop. More measurement invites advances in understanding and management; more management options augment the value of universal measurement.
In the case of blood pressure, the value proposition is a matter of historical record, namely, quite massive reductions in that toll of stroke, heart attack, and kidney failure. More can and should be done, of course- but the contributions of blood pressure measurement and management to both years in life and life in years are indelible.
Which leads us back to the provocation at the start of all this: imagine a world where diet quality is measured as readily and as universally as blood pressure. Do so by supposing the same suite of implications. The routine measurement of diet quality and its contrast to what we know it ought to be would be the same, potent cue to action as aberrations in blood pressure. All but inevitably, a new and higher standard of cultural awareness and clinical care would ensue, with resources and the flow of reimbursement obliged to evolve in tandem.
The juxtaposition of what is and was (blood pressure assessment) with what is and might be (dietary assessment) helps us clearly see the scope of promise in the enterprise: changes in medical education, accreditation, standardized testing, credentialing, quality control, continuing education, record keeping, referrals, reimbursement, and risk stratification are merely illustrative.
To be clear, the routine assessment of diet quality, however universally, would not put an end by itself to the obsolete standard that ignores this most important of all outcome predictors. After all, the universal assessment of blood pressure has not assured its optimal management for all people under all circumstances. Routine blood pressure measurement was a huge stride in that direction, however; the first essential means to those propitious ends. We may expect the same by making diet quality a vital sign.
Actually, we have an even more proximal beacon of encouragement than the history of blood pressure. We have all known about “junk food” our entire lives, but no one was in the business of “measuring” it until Professor Carlos Monteiro and colleagues developed the NOVA classification system. The mere introduction of that quantitative scale has already prompted research indicting ultraprocessing as an independent factor in over-eating and weight gain, among other ill effects. Public awareness is rising, public discourse burgeoning, and we have hope- for the first time in a long time- that practice, policy, and the food supply may succumb to such scrutiny. Calling out a problem at scale, however brilliantly, may lack the implacable force for reform of quantifying its every, personal occurrence.
A quick return, before closing, to the flagged topic of obesity* referenced above. I reject the proposition that obesity is principally genetic, a disease, and warrants pharmacotherapy for all. I further reject the contention that we should look past it for fear of our bias against it. Obesity bias must be confronted and expunged as a scourge in its own right, but we need harbor no such bias to oppose rather adamantly the rampant spread of what was formerly “adult onset” diabetes in children. Pandemic childhood obesity is the principal cause of that plague, but in turn- a pandemic of poor diet quality is the primary cause of all that obesity. Routine measurement and management of diet quality thus addresses obesity without fixating on weight, by directing attention further upstream. A robust, societal effort to improve diet quality is gratifyingly more about finding health than losing weight, placing the emphasis where it rightly belongs.
So, here we are. There was a time before we knew we should measure blood pressure universally; there was a time before we could. Due to advances in understanding and methods, that is all history now. Our thought experiment asks: can that history repeat itself?
We have heard from on high and from within the House of Medicine that diet quality should be measured routinely, i.e., treated as a vital sign. Historical methods of assessment don’t allow for this, costing too much in time, effort, attrition, accuracy, and yes, money. But innovation in this area has come at last, and now- we might append “could” to “should.”
Will diet quality be a vital sign, any time soon? Our thought experiment, though illuminating, does not shine its light quite so far. It does, however, invite a response: I can’t imagine why not.
David L. Katz, MD, MPH, FACPM, FACP, FACLM, is the Founding Director (1998) of Yale University’s Yale-Griffin Prevention Research Center, and former President of the American College of Lifestyle Medicine. He has published roughly 200 scientific articles and textbook chapters, and 15 books to date, including multiple editions of leading textbooks in both preventive medicine, and nutrition. He has made important contributions in the areas of lifestyle interventions for health promotion; nutrient profiling; behavior modification; holistic care; and evidence-based medicine. David earned his BA degree from Dartmouth College (1984); his MD from the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training in Internal Medicine, and Preventive Medicine/Public Health. He is a two-time diplomate of the American Board of Internal Medicine, and a board-certified specialist in Preventive Medicine/Public Health. He has received two Honorary Doctorates.
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