Originally, buttermilk referred to the thin liquid left over from churning butter from cultured or fermented cream.

The acidic environment also helps prevent potentially harmful microorganisms from growing, increasing shelf life.

[4] Traditional buttermilk is still common in many Arab, Indian, Nepalese, Pakistani, Finnish, Polish, Dutch, German, Danish, and Austrian households, but rarely found in other Western countries.

[5] In Arab culture, buttermilk is commonly sold ice cold with other dairy products.

Commercially available cultured buttermilk is milk that has been pasteurized and homogenized, and then inoculated with a culture of Lactococcus lactis or Lactobacillus bulgaricus plus Leuconostoc citrovorum to simulate the naturally occurring bacteria in the old-fashioned product.

Acidified buttermilk is a substitute made by adding a food-grade acid, such as white vinegar or lemon juice, to milk.

Commercially produced buttermilk is comparable to regular milk in terms of food energy and fat.