Buttermilk consumption above 1oz/7g contains moderate amounts of Lactose and should be avoided in people who malabsorb it.
Lactose-free alternatives are recommended.
Buttermilk is a fermented dairy drink. Traditionally, it was the liquid left behind after churning butter out of cultured cream; most modern buttermilk is cultured, however. It is common in warm climates (including the Balkans, South Asia, the Middle East, and the Southern United States) where unrefrigerated fresh milk sours quickly.
Buttermilk is comparable to regular milk in terms of calories and fat. One cup (237 ml) of whole milk contains 157 calories and 8.9 grams of fat. One cup of whole buttermilk contains 152 calories and 8.1 grams of total fat. Low-fat buttermilk is also available. Buttermilk contains vitamins, potassium, calcium, and traces of phosphorus.