1
$\begingroup$

After discussing this with some colleagues, I devised the theory that you could drink more coca-cola in a single sitting than you could water, without killing you.

Defining the volume it would take for one of the liquids to kill you as the 'x volume'.

Thus the hypothesis goes that the x volume for water would be lower than that of coke.

This is based on the notion that water would affect the body's water potential significantly more than the cola solution. For instance, the large volume of water would diffuse, via osmosis, into your blood and this would reduce the water potential of the blood, which would in turn diffuse into your cells which would in turn damage the micro environments and prevent proper enzymatic activity in all aspects of the cell cycle: which would have devastating affects on the brain function. Given enough water: something that can be read about here (water intoxication).

Coca-cola on the other hand which has an acidic pH -- though I'm not entirely sure of it's water potential -- would not have the same disturbance on somatic cells in the body due to the acids and sugars. However, although the large consumption of cola may have longer term effects: would the x volume of coca cola be higher than that of water?

$\endgroup$
  • 1
    $\begingroup$ What is the duration of a "single sitting"? There are many other additional factors. You may die of some other effects due to the cola consumption. Without additional details this question cannot be answered. $\endgroup$ – WYSIWYG May 23 '16 at 5:33
3
$\begingroup$

The LD 50 listed on the wikipedia page you link to is 90 mL/kg, which would be about 6 liters for a 68 kg (150 lb) person. This is consistent with at least one report, where someone died from drinking 7 liters of water in 1.5 hours.

The mechanism by which water kills people is by lowering the amount of ions (chiefly sodium) in the blood. A condition called hyponatremia.

Coke contains four relevant looking ingredients: Water, sugar, phosphoric acid, caffeine. Coke also has carbonic acid from the carbonation, but I'll assume we're either talking about uncarbonated Coke, or that the carbonation does not contribute to toxicity (perhaps a bad assumption).

Before worrying about whether the water will kill you, let's verify that the caffeine and sugar won't kill you first.

It seems unlikely that the caffeine in the coke would kill you before the hyponatremia. The concentration of caffeine in coke is about 0.1 mg/mL, and the LD50 is > 150 mg/kg, so for the same 68 kg person, it would take about 100 L of coke to get a lethal dose of caffeine.

The sugar in coke is more deadly, but still not as bad as pure water. There are about 0.11 g sugar per mL of coke. The LD50 of sucrose is apparently around 30 g/kg. So it would take about 2 kg of sucrose to kill our 68 kg person. That is about 18.5 L of Coke.

The concentration of phosphoric acid in Coke is about 5 mM which is about 0.5 mg/mL. The LD50 is about 1530 mg/kg. Which works out to about 212 L of Coke to kill by phosphoric acid.

Now that we've ruled out some other possibilities, lets get back to whether coke will kill you faster or slower via hyponatremia than pure water will.

Take another look at the the nutrition information for Coke. Notice that Coke actually contains some sodium, about 0.13 mg/mL in fact. A drink called "Powerade Isotonic" which claims to have a proper electrolyte balance contains sodium at 0.28 mg/mL.

So given that (A) what kills you first from drinking too much water is hyponatremia. (B) Coca-cola contains a non-trivial (but still less than many electrolyte drinks) amount of sodium. and (C) other potentially toxic components of Coca-Cola, such as acid and caffeine, require much higher doses to be toxic. It seems reasonable to conclude that Coca-Cola has a lower acute toxicity than distilled water.

Caveats: I did not consider osmolarity. There could be some effect here that I'm overlooking. I did not consider the effects of carbonation (soluble carbonic acid). For people with certain medical conditions, such as diabetes or caffeine sensitivity, Coca-Cola may be toxic at much lower doses than for other people.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.