Diet Coke: Make a Break?
As the only ‘diet product’ I’ve ever had the stomach for(!), reports that diet coke and other artificially-sweetened drinks are noxious to our health understandably sink my heart a little. While there are studies extolling the virtues of these drinks as weight loss catalysts, they tend to be sponsored by the industry and therefore inextricably tainted with bias, along with other limitations.
I’m well aware that my (albeit intermittent) diet coke habit confers no nutritional benefit. The caffeine it contains also has diuretic properties, i.e it promotes the production of urine which can be dehydrating so not exactly as thirst-quenching as its advertising suggests! Any energy hit is temporary and a can of diet coke imparts a measly 42mg of caffeine, as opposed to the more respectable 100mg or so you’d glean from a mug of coffee and without the accompanying aspartame. Green tea would be an even better choice! Diet coke also contains phosphoric acid which erodes tooth enamel… The list of negatives goes on!
The results of a study published in The Canadian Medical Association Journal earlier this month catchily entitled Nonnutritive (a.k.a. artificial) sweeteners and cardiometabolic health: a systematic review and meta-analysis of randomised control trials and prospective cohort studies evoked another heart sick moment. The authors crunched the numbers from 37 studies involving over 400,000 people. (7 were randomized controlled trials – the gold standard of scientific research – where elimination of bias is the aim of the game; participants are randomly assigned to either the group receiving the treatment under investigation- drinks with artificial sweeteners in this case- or to the group receiving standard treatment or placebo. 30 were cohort studies, where people are followed for a defined period of time to gauge their risk of developing the disease in question.)
This review concluded that the randomised controlled trials “do not clearly support the intended benefits of nonnutritive sweeteners for weight management” and that observational data “suggest that routine intake of nonnutritive sweeteners may be associated with increased BMI (body mass index) and cardiometabolic risk (i.e. risk of developing heart disease, stroke and diabetes)”.
Further research is warranted according to study author Dr. Meghan Azad: “I think there’s an assumption that when there are zero calories, there is zero harm, (but) there’s more to it than calories alone”.
Things like associated habits must obviously be taken into account here but there evidence against artifically-sweetened drinks is mounting…
Diet drinks have been shown to lead to compensatory over-eating. The theories behind this phenomenon are manifold. Akin to the way exercise has been shown to lead to compensatory food intake, consumption of artificially sweetened drinks may lead to compensatory over-eating to ‘balance out’ abstaining from a calorific drink.
The artificial sweetener (aspartame in diet coke) also whets the appetite of our sweet taste buds (and mine certainly need no encouragement) leaving us prone indulging cravings for sugar-laden snacks… More compensatory food consumption!
Intake of artificially-sweetened drinks has been shown to trigger insulin production in the same mode regular ones do, leading to weight gain with all of its attendant medical sequelae. In addition, artificial sweeteners are associated with a reduction in the appetite-regulating hormone leptin.
Artifical sweeteners have been shown to upset the gut microbiota (bugs) in mice, rendering the poor critters more susceptible to insulin resistance which leads to weight gain and the development of diabetes in the longer term.
Diet drinks also contain substances that pose great difficulty to digest, resulting in their storage in fat cells in order to keep them away from our vital organs. The hypothesis is that the process stimulates increased production of fat cells to accommodate the storage of these chemicals.
(While research into a possible link between aspartame and cancer continues, no robust evidence has emerged to date.)
An article published earlier in 2017 in PLOS Medicine (Artifically Sweetened Beverages and the Response to the Global Obesity Crisis) concluded that in light of the dearth of reproducible evidence to support their use in preventing obesity as well as the lack of studies on their long-term effects, they should not be promoted. The piece also emphasised the need to study their potential deleterious environmental impact, the “misuse of natural resources, pollution, or ecotoxicity”, without any conflicts of interest.
So what now? Is this finally the requiem for diet drinks? Confusion reigns supreme as always! I’d row in with the advice of Susan Jebb OBE, a nutrition scientist, and the Professor of Diet and Population Health at the University of Oxford: “Water is without question the best drink to choose, for health and the environment, but for many… this will be too hard a change to make. Artifically sweetened drinks are a step in the right direction to cut calories.”
If you are sufficiently motivated to wean yourself off the stuff but cannot tolerate the cravings for something sweet, try a couple of squares of dark chocolate or a serving of mixed berries to retrain those pesky taste buds. Stevia-flavoured drinks are a step in the right direction, with no artifical sweeteners or flavours. Don’t forget some calorie- and aspartame-free sparkling water if you find yourself missing your fizz-fix!