Calcium in Milk vs. Soy Milk, Almond Milk and Rice Milk

Milk and dairy products are a major source of dietary calcium. You are required to take in at least 1000 milligrams of calcium per day though your diet, and having 2 to 3 servings of dairy everyday can help ensure proper body functions like cell metabolism, conduction of nerve impulses and healthy bone development. However, milk may not be suitable for everyone such as people with lactose intolerance or casein allergies. Fortunately, nondairy alternatives with a similar taste to milk can be made from soy, almond and rice. By nature, these products have quite different calcium contents, but through food fortification, the calcium deficits in various nondairy milk products are no longer an issue.
 
Natural Level of Calcium in Dairy and Nondairy Milk

In nature, it is without a doubt that cow milk holds the highest amount of calcium compared to other milk alternatives. Each 8 ounce serving of milk contains about 300 milligrams of calcium. Soy milk comes in second at approximately 50 milligrams. Because calcium in almonds and rice are significantly lower compared with the previous two, milk made from these ingredients have a much lower calcium content. There are only 2 milligrams of calcium in an 8 ounce cup of plain almond milk, and less than 1 milligram is found in rice milk. Therefore, homemade or unfortified almond and rice milk should not be used to replace cows milk as a source of calcium.
Calcium and Vitamin D Fortifications

Popular producers like Silk, Blue Diamond and Rice Dreams profoundly make up for the insufficiencies of natural nutrition in their product. In terms of meeting the dietary requirement of calcium, these companies usually partner the addition of calcium with vitamin D. This is because your body needs vitamin D in order to absorb calcium. Because cows milk is naturally high in calcium, it is only necessary to incorporate extra vitamin D during fortification. After the process, cow, soy, almond and rice milk are approximately equivalent in both calcium and vitamin D concentration. An average cup of fortified dairy and nondairy milk contribute to about 30% of your daily need for calcium and 25% to 45% of your need for vitamin D.
Calcium Absorption in Dairy and Nondairy Milk

A lot of people argue that calcium found in natural foods is better absorbed by the body than from fortified foods. Whether this argument is true really depends on a number of factors.
Stomach Acidity: Calcium is better absorbed in acidic conditions. In this regard, lactose found in dairy milk does accelerate your body’s calcium uptake.
Presence of phosphate: Phosphate can inhibit calcium absorption. Studies have shown that fortification of nondairy milk with tricalcium phosphate have 25% less absorption efficiency compared to cow milk. However, if fortification is done with tricalcium carbonate instead, this disadvantage in absorption no longer exists.   
Calcium Precipitation: Fortified calcium can precipitate to the bottom of the container which decreases the total availability of calcium in your milk. Shaking your cartons well before serving is crucial to avoiding this problem.
Estrogen: Soy milk contain plant estrogen that increases your body’s ability to absorb calcium.