A smoothie is a blended, chilled, sometimes sweet beverage made from fresh fruit or vegetables. In addition to fruit, many smoothies include crushed ice, frozen fruit, honey or frozen yogurt, although some smoothies are 100% fruit. They have a milkshake-like consistency which is thicker than slush drinks. Unlike milkshakes, they usually don't contain ice cream, but can contain milk. Smoothies are marketed to health-conscious people, and some restaurants offer add-ins such as soy milk, whey powder, green tea, herbal supplements, or nutritional supplement mixes. Smoothies became available in the United States in the late 1960s when ice cream vendors and health food stores began selling them. By the 1990s and 2000s, smoothies became available at mainstream cafés and coffee shops, and in pre-bottled versions at supermarkets.