I'm wondering why dairy products help eliminate the 'hot' of spicy foods?

I think milk coats the esophagus negating whatever aspects of heartburn spicy foods bring up – last pregnancy, I consumed about a gallon of milk daily to deal with heartburn.

The milk temporarily coats your mouth, esophagus and stomach. The same reason why liquid antacids work faster than tablets.

The fats in milk take care of the spice better than water or other liquids.

Milk contains a protien casein, that calms the taste buds.

I have an antique fountain pen that is made out of casein

Consider that oil and water don’t mix, and most spices are oil based. If you wash down spicy food with water, the oil will just slide off. The fat in milk binds with the oil in the spices in a way that water can’t.

Many dairy products are high in sugar. Sugar counteracts the active ingredient (capucin) in hot peppers. The Scoville scale measures how much sugar is necessary to counteract the effect of the a certain amount of hot stuff.

From Wikipedia:

Cold milk is the most effective solution against the burning sensation (due to casein having a detergent effect on capsaicin[20]) and cold sugar solution (10%) at 20°C/68°F is almost as effective.[21]

To expand on the “detergent effect”, I found another person’s explanation via Google search that is good:

Milk contains casein, a lipophilic protein that surrounds and washes away the fatty capsaicin molecules(which cause the ‘burn’) in much the same way that soap washes away grease. A nice heavy beer will do the trick too, to a lesser extent.

@lilikoi Beer came to mind when I was reading this, also, especially a warmed cup of dark, buttered ale.

acid neutralizer plus it coats the digestive tract