The amount of calcium in a product is indicated as the percentage of daily requirements based on 1000 milligrams (mg) of calcium per day. To calculate milligrams of calcium, simply add a zero to the percentage of calcium that appears on the label. For example, if 1 cup of milk contains 30% of the calcium needed, then it contains 300 milligrams of calcium (see food label below). Calcium requires an adequate amount of vitamin D for the body to absorb.
In the United States, many calcium-containing food sources, such as milk, are fortified with vitamin D. Getting enough calcium to prevent bone thinning throughout a person's life can be more difficult if that person has lactose intolerance or another reason, such as a tendency to have kidney stones, to avoid calcium-rich food sources. Calcium deficiency also affects the heart and circulatory system, as well as the secretion of essential hormones. There are many ways to supplement calcium, including a growing number of fortified foods.
The daily value (DV) on the nutrition facts label indicates how much of a nutrient (such as calcium) a serving of the food contains. Recommendations for calcium and other nutrients are included in the dietary reference intakes (DRI) prepared by the Food and Nutrition Board of the National Academies of Sciences, Engineering and Medicine.
