The dose makes the poison. In that sense at least, Coca-Cola is toxic.
Coca-Cola has a very low acute toxicity, i.e. there is basically no way you are going to die from an overdose of Coca-Cola.
As for the long term effects, let’s go through the main ingredients:
- Carbonated water: I actually talked about this once in Adrien Lucas Ecoffet’s answer to Is there any significant difference between drinking sparkling versus still water? Long story short: it’s pretty much the same as regular water.
- Sugar: causes tooth decay, obesity, a bunch of other stuff. Don’t drink too much and brush your teeth and you’ll be fine.
- Phosphoric acid: the acid part can accelerate dental erosion. This is pretty much the case with any other soft drink and most fruit juices (including the orange juice). Again, don’t drink too much of it and you’ll be OK. There have also been concerns that phosphoric acid causes lower bone density, however, later studies have shown both that lower bone density was mostly caused by Coca-Cola consumer not drinking as much milk, and that the next guy is a more likely culprit:
- Caffeine: probably the most toxic ingredient in Coca-Cola. It’s addictive, people can overdose on it (it’s really hard though), and it seems to be one of the reasons why Coca-Cola does cause lower bone density. Then again, 7 oz. the cup of coffee contains more than twice as much caffeine as a 12 oz. can of Coke. Also, the Coca-Cola company sells Caffeine-Free Coke if you are really concerned about this.
- Class IV caramel color: there is some controversy around this, class IV caramel color contains trace amounts of 4-MEI, a carcinogenic compound. Consuming 30 micrograms per day might lead to a 1:100,000 chance of developing cancer. If you are in California then each can of coke contains 4 micrograms, so you should be fine. In other countries, it can potentially be up to 250 micrograms, so that’s less good. Note, however, that the 30 micrograms and 1:100,000 figures come from a study using much higher doses on rodents. In fact, according to the FDA: “[a] person would have to drink more than a thousand cans of soda in a day to match the doses administered in studies that showed links to cancer in rodents.” Basically, the evidence is extremely weak.
- Natural flavorings: well, that’s just not precise enough.
I’m going to stop right there. I’m sure some people feel like Coca-Cola is indeed dangerous after reading this. If you do, please read it again and ask yourself this: is there any “danger” on this list that doesn’t apply to other, widely accepted products (such as coffee or orange juice) or that isn’t supported by extremely weak evidence? There is none.
And here’s the thing: when we talk about the dangers of cigarettes and alcohol, we have strong evidence, based on real human beings who really did get sick that those substances, all other things being equal, lead to an increased risk of cancer and other sicknesses.
But when people talk about the dangers of Coca-Cola, they do the same thing I just did: they isolate individual ingredients and illustrate how a highly unreliable study proved that this ingredient could be harmful at incredibly high does on rodents or individual cells (btw that’s pretty much the current strength of the evidence against aspartame). You could do that with any product.
The reason for this is that there has never been, as far as I know, any study that was able to find a correlation, all other things being equal, between Coca-Cola consumption and mortality. You can pick and choose details all you want, the fact remains that this is the bigger picture.
I find it crazy that some people are comparing the Coca-Cola Company with Philip Morris and such. Given the low strength of the evidence against Coca-Cola, I find it highly likely that those people are just making dubious health claims as part of a bigger political campaign against the Coca-Cola company and corporations in general.
So drink acidic drinks in moderation, eat healthily, brush your teeth, and don’t forget to drink milk and you’ll be all right.