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Before I begin, I want to make something clear: this is not your standard definitive guide to whatever. I’d like to be able to issue a proclamation regarding diet soda that stands the test of time immemorial, but I cannot. Research is still in its infancy, and exactly what diet soda does to those who drink it — if anything — is incredibly confusing. The one thing I can say with any certainty is that, while it’s unfair to say it will kill you or give your unborn child prenatal tumors or make you impossibly obese, you’re probably better off without diet soda. It tastes weird, the list of unpronounceable ingredients is too long for my comfort level, and I’ve seen one too many unsuccessful dieters that seem to live on the stuff.
There are two things to consider when making any conclusions about diet soda’s place in a healthy diet. Do the ingredients used in diet soda pose a threat to your short-term or long-term (or that of your offspring’s) health? Is it a kind of sugary methadone, impeding healthy eating by making it harder to kick the desire for sweet things in your mouth because, well, you’re constantly putting things in your mouth that mimic sugar? Let’s dig in.
First, the ingredients. What goes into a can of your average diet soda?
Carbonated water, some sort of food coloring, and preservatives like potassium benzoate are all innocuous enough. Nothing to worry about there. You won’t see Mercola issuing dire warnings about Caramel Color No. 76 anytime soon. It’s the other stuff that interests (or worries) us: artificial sweeteners and (to a lesser extent) phosphoric acid. Let’s take a look at the two major sweeteners in popular use, aspartame and sucralose. Are they dangerous?
Aspartame gets a bad rap. High dose rat studies implicate it as a carcinogen, but in exceedingly large amounts. A can of diet soda a day probably won’t give you cancer. Would I avoid it as a pregnant mother? Yes. Would I be wary of drinking several cans a day? Yes. The basic takeaway is that while the clinical evidence of immediate danger upon normal ingestion of aspartame is lacking, inconclusive, or unclear, the vast amount of anecdotal evidence from people linking aspartame to headaches, migraines, panic attacks, and other maladies gives me great pause. I mean, the stuff tastes horrible, and that’s enough for me, but some people appear to have real health issues with aspartame. Not everyone, obviously, but some do. If aspartame appears to give you trouble, don’t let PubMed convince you that it’s harmless. It may very well be safe in the amounts we typically consume in the majority of people, but you can’t ignore your own experiences.
Also known as Splenda, sucralose is a popular sweetener that’s often called “natural” because it’s the product of selective sucrose chlorination. It’s 3.3 times sweeter than aspartame and 600 times sweeter than sucrose. It seems to have less of a disgusting aftertaste than aspartame (it’s all foul to me, though). Like aspartame, most of the studies reporting negative effects used insanely high doses of sucralose. I’m talking doses in the area of thousands of Splenda packets a day for months on end. I’m no fan, but I don’t think normal consumption of the stuff will kill you. There was a study that found normal doses (between 1.1 and 11.1 mg/kg per day; recommended maximum daily dosage is 5 mg/kg) of sucralose negatively impacted the gut flora in rats and lead to weight gain, although a later review called the study’s results into question. I’ll pass, but thanks, expert panel. There’s also the fact that sucralose is usually combined with something called acesulfame-K (potassium), another sweetener that many researchers think needs more toxicity tests. My take? Studies showing negative effects may be overstated or misguided, but why take the risk for that weird chemical aftertaste? Just avoid the stuff to be on the safe side.
And then there’s phosphoric acid. Here’s how the story supposedly goes: phosphoric acid, which soda makers use in place of pricier citric acid, leaches calcium from your bones and reduces bone mineral density. Is it true? Well, it’s become pretty clear that foods containing dietary phosphorus — like meat, dairy, and other “evil” foods — strengthen bones, rather than leach from them. But phosphorus isn’t exactly the same as phosphoric acid, which epidemiological studies have connected with loss of bone mineral density and osteoporosis. One in particular found that only colas (both diet and regular) were strongly associated with loss of bone mineral density. What do colas have that other diet sodas largely do not? Caffeine plus phosphoric acid. A more recent controlled trial found that only fizzy drinks containing caffeine resulted in increased calcium excretion; phosphoric acid content exerted no effect, either alone or in concert with caffeine. I don’t think we can implicate phosphoric acid just yet.
Okay, but remember: we’ve got to be careful when analyzing a food’s worth by singling out one of its constituent parts for good or for bad (although diet soda is by all definitions not food, it is a consumable whose stated purpose is to help dieters lose weight by avoiding sugar). Let’s judge diet soda on that. It may be technically safe to consume, but does it do its “job”? Does it help us lose weight by replacing our sugar intake with non-caloric sweetener intake and reducing cravings?