Dairy foods aside, however, there are several other foods that are good sources of calcium, as shown in the following table. Several factors affect how calcium is absorbed in the body. Vitamin D, phosphorus and lactose, the sugar found naturally in milk products, may help to improve calcium absorption. Too much oxalate, a substance found in certain fruits and vegetables, can bind with calcium decreasing the absorption as well. In addition to calcium, vitamin D intake is important for bone health.
Vitamin D helps regulate bone rebuilding, blood calcium levels and the absorption of calcium.
Typically, vitamin D comes from sunlight and from foods, such as milk, that have been fortified. Recent studies indicate that without adequate vitamin D, risk for osteoporosis is increased, particularly in adults over age 50, and in people who live in northern climates where exposure to sunlight is limited. Research is currently underway to clarify the role of calcium in these areas. Hypertension - Too little calcium in the diet increases the risk for high blood pressure. Because calcium influences muscle contractions, researchers believe it may have a role in preventing high blood pressure by decreasing the muscle contractions in blood vessel walls.