Drink plenty of fluids with calcium supplements to avoid constipation. pro vita keto The lactose and vitamin D in the milk help to enhance calcium absorption. If you don't drink milk and want an alternative to calcium pills, consider calcium-fortified juice or soy beverage. One cup of calcium-fortified juice or soy beverage can contain about 300 milligrams of calcium, the same amount as in a cup of milk, and provides vitamin C, folate, and other nutrients. Still, you need a vitamin D source to aid absorption; some calcium-fortified juices and soy beverages are also fortified with vitamin D.