It was first suggested at the 1984 Consensus Development Conference on Osteoporosis that increased intake of calcium might help to prevent osteoporosis.  Osteoporosis affects millions of people in the United States and is the major underlying cause of bone fractures in postmenopausal women and the elderly.  Two important factors that influence the occurrence of osteoporosis are:

• 1. optimal peak bone mass attained in the first two to three decades of life.
• 2. the rate at which bone is lost in later years.

Optimal calcium intake may vary according to a person's age, sex, and ethnicity.  The current Recommended Dietary Allowances (RDA) for calcium intake is to be used as a guideline to determine optimal calcium intake.
 

OPTIMAL CALCIUM REQUIREMENTS

	Group	Optimal Daily Intake (in mg of calcium)
	Infants
	Birth-6 months	400
	6 months-1 year	600
	Children
	1-5 years	800
	6-10 years	800-1,200
	Adolescents/Young Adults
	11-24 years	1,200-1,500
	Men
	25-65 years	1,000
	Over 65 years	1,500
	Women
	25-50 years	1,000
	Over 50 years (postmenopausal)
	On estrogen	1,000
	Not on estrogen	1,500
	Over 65 years	1,500
	Pregnant and nursing	1,200-1,500

 
Dietary sources are the best way to attain optimal calcium intake.  For most of us, dairy products are our main source of calcium because of the high calcium content within these products (e.g., approximately 250-300 mg/8 oz milk).  Other good sources of calcium include green vegetables (e.g., broccoli, turnip greens, Chinese cabbage), some legumes, canned fish, seeds, nuts, and certain fortified foods (e.g., fortified juices, fruit drinks, breads, cereals).  The Food Guide Pyramid of the US Department of Agriculture recommends 2-3 servings per day of dairy products and 3-5 servings of vegetables.

For some individuals, calcium supplements may be the preferred way to attain optimal calcium intake.  Calcium supplements are available as various salts and most preparations are well absorbed.  The most widely used salts are calcium carbonate and calcium citrate.  Of the calcium supplements commercially available calcium carbonate contains the highest proportion (40%) of elemental calcium by weight.  There have been recent studies that show that calcium carbonate can have some problems with absorption if it is not taken with food. 

Calcium carbonate is the source of calcium used in Tums^®, Caltrate^®, Os-Cala^®, and Viactiv^®, and many other over-the-counter products.  As an alternative, calcium citrate (21% elemental calcium) does not require gastric acid for optimal absorption.  So it can be taken without regards to meals.  It is found in Citracal^®.