Did you know that just because you consume the recommended 500-1500 mg (depending on sex, age, and other factors) of calcium per day, this does not necessarily mean your body is actually getting that much? Many things affect the way calcium is absorbed by the body, and if you're not mindful of when and how calcium is consumed, you may be limiting the amount your body can utilize.
We need calcium to build strong bones and to help with muscle function, along with a host of other roles it plays in our bodies. Calcium is especially important for women, whose smaller frames are more prone to osteoporosis (loss of bone density, causing breakdown of bone structure and brittle bones) as they age.
In fact many young women may be at a much higher risk than they realize for developing this condition as they grow older, for a number of reasons. Diet, exercise, and the use of medications and oral contraceptives can all play a role in the way calcium is absorbed by the body and how likely a person is to have bone density issues as they age.
Throughout a person's 20's and 30's, bone density in the human body generally increases. Bones stop growing long before then, but they can still become harder and more dense if enough calcium is taken in. We move calcium in and out of our bones every day. Prior to age 30, the amount of calcium going into the bones exceeds the amount depleted from the bones. After age 40, bone density begins to decline because our body moves calcium out of the bones faster than it is replenished. This is when problems begin to show up for many women, and why it is important to take in enough calcium to build bones as hard and as dense as possible before age 30.
One of the factors that can affect calcium absorption is the amount of vitamin D (the "sunshine" vitamin, also fortified in many diary products and cereals) present in the body. Vitamin D is essential for calcium to be used in building bones, teeth, and in it's other roles. The source of the calcium can also determine how well it is absorbed by the body; milk and foods made with milk are the best sources of calcium, but calcium from plant matter such as turnip greens is also well-absorbed. In general, it is better to get calcium through diet than through supplements, but especially for older women whose recommended intake is 1500 mg daily, it can be tough to reach that amount through diet alone (a glass of milk has about 300 mg of calcium). The important thing to remember about supplements is that the body cannot absorb more than 500 mg of calcium at a time. So if you are consuming more than 500 mg of calcium through supplements or a combination of diet and supplements, make sure it is spread out over the course of the day and not ingested all at once.
For more information on Osteoporosis prevention, visit the National Osteoporosis Foundation website at: http://www.nof.org.