Tomorrow is the first official day of summer, and as the weather heats up, I often occasionally dabble in less sedentary activities than watching television or attending a screening. To offset the winter weight I might lose by engaging in activities that might involve more than lifting up a heavy remote, I like to eat ice cream. I prefer peanut butter and chocolate ice cream, but I’m sure many of you have your own preferences.
But a question I’ve often wondered, because I’m lousy with science and biology, is this: Why does ice cream make me so thirsty? Ice cream is basically frozen milk, and milk doesn’t make me thirsty (although, it does make me gag unless it’s heavily flavored with Cinnamon Toast Crunch debris), so why should ice cream make me thirsty? It seems counterintuitive, and yet, that cold, refreshing dessert gives me that same dehydrated feeling I get after a heavy night of drinking.
How does that make sense? We checked in (i.e., looked it up on the Internet)with Michael Gasink an, undergraduate in Biology/Environmental Science at College of William and Mary, who provided a very simple explanation:
“Salt is one of the ingredients of most ice creams. Salt makes you thirsty.”
This is overly simplified, I know, but in all honesty that is pretty much what happens. Ice cream makes you thirsty on the same principle. For those with more biology, it all boils down to osmosis.
Osmosis is the tendency for water to travel across a semi-permeable membrane from a place of low concentration of solutes to a place of high concentration of solutes.
When you eat ice cream, you blast your body with all sorts of solutes. Ice cream has salts, but also sugars fats, amino acids, and more for your body to absorb into the blood stream. When your blood becomes laden with these chemicals, (mostly sugars) your blood becomes more “concentrated,” giving your brain (hypothalamus) the signal of dehydration. When water in the hypothalamus leaves to the blood through osmosis, then the blood concentration is greater than that of the hypothalamus. This triggers the thirst response in the body and brain.
If you were dehydrated, there would be a high concentration of solutes in your blood, so you would become thirsty. Eating ice cream, in a sense, makes your body think it is dehydrated, and in a sense, I suppose it is.
This is one of the reasons that diabetics are thirsty all the time. Diabetes causes high blood glucose, and that increased concentration of blood solutes makes the diabetic feel thirsty.
In short: It’s the salt. Why is there salt in ice cream? Because salt allows you to bring the mixture of ingredients in ice cream below the freezing point of water without turning it into a frozen block, like an ice cube.
The Internet is awesome.