I like Pepsi Max. It’s my favourite soft drink. Sadly, PepsiCo is not paying me to say that, it’s just a boring fact. Whilst I would never claim that it is a health drink (if there even is such a thing), there is no sugar and no calories in Pepsi Max and so I figured it isn’t doing me any harm.
For reasons I don’t yet fully comprehend, my girlfriend has embarked on a crusade against my favourite beverage; she has decided I drink too much of it and that it is bad for me. A few evenings ago she deployed Google and spent half an hour rattling off a seemingly endless list of maladies that the ingredients of Pepsi Max are responsible for. Admittedly, I stopped listening after about five minutes but everything was in there from headaches to diabetes and, yep, you guessed it, cancer.
I couldn’t think of any good reason why a diet cola would cause a proper illness; I’ll concede the headaches, maybe the caffeine could cause them, I would have to check that out. I was aware that there were scare stories about artificial sweeteners but I vaguely remembered hearing that they were baseless. There was no way, then, that I was giving up my favourite drink without a fight. So, here it is, the defence for diet soda. Obviously I have a dog in this fight but I have done my best to be impartial. You be the judge.
The artificial sweetener used in most diet sodas is aspartame. It was approved for use in the early 80s and pretty much ever since it has been dogged by rumours of its ill effects. I’ll start with one legitimate concern. Phenylketonuria is a rare genetic disease that means people are not able to metabolise the amino acid phenylalanine. Given that aspartame is simply the two amino acids aspartic acid and phenylalanine stuck together this can cause a problem for those affected. People with phenylketonuria know they have the disease long before they ever get to an age when they’re drinking diet soft drinks and they know they need to avoid it much the same way someone with a nut allergy needs to be careful.
As for the diabetes, cancer and other scare stories as championed by crooks like Jospeh Mercola, they are just that: scare stories. Aspartame is probably one of the most studied food additives in history and every time it is looked at the results are dead negative.
There have been various meta analyses and reviews of the hundreds of studies conducted on aspartame over the years; the most recent ones are a 2007 review by the FDA in which they concluded:
Considering results from the large number of studies on aspartame’s safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food.
A couple of years later the European Food Safety Agency similarly concluded:
Overall, the Panel concluded, on the basis of all the evidence currently available… that there is no indication of any genotoxic or carcinogenic potential of aspartame and that there is no reason to revise the previously established ADI for aspartame of 40 mg/kg [body weight].
The US ADI is 50 mg/kg. The average soft drink contains about 180 mg of aspartame and so a 70 kg adult would need to drink in excess of 16 cans per day to get near the limit. Remember also that when authorities around the world, like the 90 from which aspartame has approval, set a safety limit for human consumption of a substance they normally set the limit two orders of magnitude below the lowest level at which there is a detectable impact on human health. In our case then, it’s likely that more than 1,500 cans would need to be drunk before there would be a problem caused by the aspartame.
Finally, in 2015, another review looked specifically at the question of any potential cancer causing properties of aspartame, “The available data therefore support the conclusions of the European Food Safety Authority (EFSA) that aspartame is non-genotoxic.”
With regards to weight gain, for a time there was a theory that those who drink diet sodas actually ended up consuming more calories than those who don’t because they over compensate i.e. they think that because they aren’t drinking a sugary drink they can get more calories elsewhere. There even appeared to be a couple of studies that supported this idea; however, once higher quality studies were done that controlled for starting weight and calorie consumption of those involved it was realised that causality was being reversed. It isn’t that drinking diet soft drinks makes you eat more and get fat, it’s that people who eat too much and are fat drink diet soft drinks as a way of trying to lower their calorie intake.
So there you have it. To the best of my abilities that is the skinny on why aspartame won’t make you fat. Or give you cancer. It feels to me like there is a degree of overlap here with the standard anti-GMO arguments: artificial additives are bad, natural is best, disgust at imagined contamination of the food chain. These arguments, though, are just as baseless in this circumstance as in that of GMOs. My girlfriend is half right, I do need to lose some weight, but there’s nothing wrong with my Pepsi Max.