Milk contains all the known vitamins and is an especially good source of ___.

Milk is especially known for being an excellent source of riboflavin, also known as vitamin B2. Riboflavin plays a crucial role in energy production and the metabolism of fats, drugs, and steroids. It also helps in the maintenance of healthy skin, eyes, and nerve functions, making it important for overall health.

While milk does contain other nutrients, including vitamins A, D, and calcium, riboflavin is specifically highlighted due to its abundance in milk compared to other food sources. This makes milk a standout choice for individuals looking to increase their riboflavin intake through their diet. The presence of riboflavin in milk, along with its role in energy production, reinforces the importance of dairy products in diets, especially for populations that require higher nutrient intake.