Calcium and health
Published: April 23, 2012
Calcium is a major mineral which is essential for health and present in your body in relatively large amounts. While calcium is a key ingredient in building strong bones, this mineral has other important functions in your body such as assisting in nerve function and blood clotting.
A calcium deficiency is usually associated with stunted growth in children and osteoporosis in adults. Insufficient dietary calcium leads to calcium release from your bones to provide the calcium needed for nerve function and blood clotting. This weakens your bone structure and can lead to increased risk of bone fractures.
Calcium deficiency may also be associated withincreased risk of colon cancer.
Like other minerals, calcium is excreted from your body in small amounts on a regular basis and needs to be replenished.
Calcium is found in a wide range of foods such as milk products, fish (in bones), tofu and a variety of vegetables. Some vegetables, such as spinach, appear to provide large amounts of calcium. However, the calcium in some foods, particularly plant sources, is not particularly well absorbed into your body for a variety of reasons.
Bioavailability is the term given to how much of a nutrient your body absorbs during digestion, and for calcium may be as low as 5% (e.g. spinach) of the amount of calcium contained in the food depending on the food source.
Cooking methods may also affect how much calcium is available for absorption as minerals leech into cooking water and will be lost if the water is discarded.
Your own calcium status may influence how much calcium you absorb and components of other foods may enhance or inhibit calcium’s bioavailability.
An adequate intake (AI) of between 1000 and 1300 mg/day is recommended. This is the amount of calcium that appears sufficient for health for children and adults over the age of 9 depending on age and gender. Younger children require less calcium per day.
A tolerable upper level of 2500 g per day has also been set and above this level toxicity and adverse health effects may occur.
While it is unlikely that you will ingest potentially toxic amounts of calcium from food sources, supplemental calcium may lead to toxicity. This can result in constipation, kidney dysfunction and may interfere with absorption of other minerals.
Many people consume calcium supplements for a variety of reasons, but care needs to be taken to make sure you do not exceed the tolerable upper level. This amount includes all sources of calcium and you need to be aware of calcium fortified foods and drinks as well as calcium supplements.
If you are not sure whether you are consuming too much or not enough calcium follow the link to the indepth article about calcium which provides more detailed inrformation about calcium requirements and bioavailability.
You may also wish to consult a registered dietician who will be able to advise you as to your calcium intake and an appropriate supplement if necessary.
Whitney, E. & Rady Rolfes, S. (2005). Understanding Nutrition. Belmont, CA: Thomson Wadsworth