Can Nutrition Be More Scientific?Insight
By Gary Kantor.
This is the first in a series of short articles about newer health technologies and their application. We call these “mini-HTAs” (HTA: Health Technology Assessment). We take a snapshot of new technologies, give a glimpse of the underlying science, and suggest how to evaluate the safety, effectiveness, cost, and impact.
The science around nutrition has long been problematic. Published results go in all directions, some highly improbable (e.g. eat a handful of nuts each day and live 39% longer), with every nutrient (coffee, fat, alcohol, grain, gluten, fibre, you name it) associated in at least one study with every kind of outcome, good or bad. Confusing advice emerges that changes almost every day and leads to dietary wars. Keto. Paleo. Banting. Vegan.
Major problems include: “Inputs” aren’t well defined in many studies. Retrospective accounts of what was eaten are known to be inaccurate. Can you recall exactly what you ate for breakfast even this morning? Study subjects are often asked to assess this days or weeks later. Few studies can control and monitor everything that’s eaten “in the wild”, and when they do (i.e. the subjects are “captive”), it’s only for a few days or weeks.
Meaningful outcomes take a long time to come through, adding to research expense and effort. Study designs are often weak, and few are randomised, i.e. can control important variables that can influence the outcome. Results may be temporary – most weight-loss diets work for a while, but most aren’t sustained, and people return to their baseline (or worse) relatively quickly. Like rates of heart disease, clinical outcomes take years to evolve, and differences that might be attributed to diet become apparent. Metabolic and physiological changes are assumed (e.g. less hunger, less leaky gut, no “brain fog”) but need precise measurement, including laboratory tests.
We point you to three new technologies that can help – food diaries (apps), breath monitors, and continuous glucose monitors.
These enable every meal and snack to be logged in real-time. It’s still quite a lot of work and requires discipline – especially if you’re prone to snacking, enjoying the kind of indulgent eating (no judgement) where documenting your intake could be most helpful (and upsetting to reveal to yourself). The best food diaries enable time stamping, barcode scanning to make meal logging easy and have the largest possible food library.
In South Africa, two diaries we’ve tried (Fat Secret, MyFitnessPal) have local food products and specialities (boerewors) in their database, and local barcoded items will scan. These apps will calculate and display total calories and macronutrient fractions (protein, fat and carb). Some are free, others paid, or a hybrid (some features requiring a pro version). If you’re a real enthusiast, you might want access to the raw data; otherwise, you want highly informative yet easy to read reports.
If you “go keto”, you are making an increasingly popular choice among the growing proportion of the population trying to reduce their carbohydrate intake. Carb consumption (especially sugars and other refined carbohydrates) appears to be the major dietary factor driving the epidemic of obesity and metabolic syndrome (diabetes, high blood pressure, vascular disease). Ronaldo’s rejection of a Coca-Cola can instantly knock billions off the company’s value, so we may be at an inflexion point in dietary attitudes.
If you’re cutting carbs, the physiological changes involved in these diets could be (or hopefully are) significant. Ketogenic diets shift your cellular fuel, including in the brain, to ketone bodies. If keto is your aim, devices you breathe into can help you monitor whether your body’s fuel has changed.
The handheld Lumen ($299), which has been validated against medical grade devices, uses carbon dioxide in exhaled air to calculate the proportion of fuel (food) derived from carbohydrate. This is derived from the fact that different macronutrients “burned” by the body generate different amounts of exhaled carbon dioxide. Inhale a fixed volume of air through the device, hold it for ten seconds, and exhale fully. KeyTo ($99), a Canadian company, also uses exhaled breath but measures breath acetone, a sensitive marker of ketosis, comparable to blood concentrations of beta-hydroxybutyrate, the gold standard measure. Ketonix ($79-199), made in Sweden, also quantifies breath acetone. It’s a bit of a rigmarole to get your exhaled breath out for consistent, repeatable measurement. Interestingly, ketogenic diets are not only used by the low carb community for weight loss and other claimed benefits; they are proven effective therapies for certain forms of epilepsy.
Continuous Glucose Monitors
If you want to see the effects of dietary carbohydrate in real-time, continuous glucose monitors (CGM), recently added to benefits for type-1 diabetes by some insurers, will tell you. CGMs are increasingly being adopted by healthier people seeking better metabolic health or even better athletic performance.
The sensors cost about R1000 and use a tiny subcutaneous needle in an adhesive patch applied to your tummy or upper arm to get minute by minute glucose values from interstitial fluid. These values, measured from the fluid between your cells, not the bloodstream, generally run within 20% of blood glucose. Watch that doughnut spike your glucose! Not only diabetes, but its precursor state, pre-diabetes or glucose intolerance, become highly evident with CGM tracking.
There is fascinating research showing predictable surges in glucose with high sugar foods and significant inter-individual variation in response to the same ones. These individual variations suggest that though specific eating patterns seem clearly bad, no diet is perfect for all in the long term. Differences may be due to genetics or the gut microbiome.
Two CGMs are on the market in SA, made by Abbott (Freestyle Libre)(FL) and Roche (Dexcom). The Dexcom device requires a prescription, but Freestyle Libre is now available without. In Europe, a “sports” biosensor using the same technology has been introduced. Sensor life is two weeks (FL) or ten days (Dexcom), and the Dexcom device requires a small sensor attached to the patch. Both devices communicate with your smartphone. Data displayed in the device app can distribute data to other apps and to a companion account which can be used by a buddy, a family member – or your doctor.
We believe these technologies will help convert nutrition to a more rational endeavour. They may quieten the dietary wars over what’s best to eat, or at least show us what happens if we care to know when we eat the entire tub of ice cream hidden at the back of the freezer.
Nutritional science may improve over time. In the meantime, the devices described are now in the price range that may justify a personal investment by those with fairly deep pockets. Food is medicine, and if that’s the case, it’s probably about time to make them available in medical aid benefits. Before that happens, we will have to see reports and evidence proving not only the analytic validity of the measuring devices (CGM, ketones, acetone) but their clinical utility, ideally in randomised trials.
As always, check with your doctor before embarking on your own dietary or other health enhancement “experiments” – especially if you have a significant health condition.
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