Drinking milk helps you meet the recommended daily intake for calcium, phosphorus, potassium and vitamins A and D. You probably don't want to take your multivitamin with a glass of milk, however, because it will limit the amount of calcium and iron you absorb from your multivitamin. Orange juice would be a better beverage choice because the vitamin C it contains improves iron absorption.
Your body doesn't absorb as much calcium if you get more than 500 milligrams at a time, and combining a multivitamin with milk could cause you to go over this amount. An 8-ounce glass of 2 percent milk has about 293 milligrams of calcium, and many multivitamins contain more than 200 milligrams of calcium. Taking your multivitamin with milk could also reduce the absorption of iron from your multivitamin. Consuming 165 milligrams or more of calcium along with iron can decrease iron absorption by as much as 60 percent, according to a study published in the "American Journal of Clinical Nutrition" in January 1991. To avoid this interaction, take your multivitamin at least two hours before or after consuming dairy products, recommends MedlinePlus.