Preserving Bone Density

After puberty, bone growth ends but bone density increases until roughly age 30. Absorption and retention of calcium decreases while calcium losses increase, leaving a requirement that is estimated to be 1000 mg/day.

The drainage of calcium from bone occurs in all humans at a steady pace, but women are clearly more at risk for losses. Variability in calcium loss is best seen in pregnancy when calcium is taken from the mother’s stores for deposition in the fetus. Also, lactation creates an ongoing need for further calcium supplementation in women.

While most expectant mothers are able to replenish their needs by taking prenatal vitamins, some teens are not able to comprehend the necessity of increased calcium intake and comply. Vitamin D is also supplemented during this period in the prenatal pills, but even men and non-pregnant women should maintain adequate intake of this vitamin.

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A very important means of preserving bone density is exercise. Adults have been made aware of the benefits of exercise, especially in the elderly, for many reasons, including the preservation of bone mineral content.

It is also well accepted that increased activity will create forces on the bone that trigger increased bone density - a natural response to protect highly used bones by making them sturdier. Hence, it makes sense that kids who get more exercise will also have stronger bones.


To maximize the beneficial effects of increased bone density in adults, we need to enhance the consumption, storage, and preservation of calcium in kids and teens. This starts with adequate and appropriate intake of milk or substitute drinks, plenty of exercise, replacement as needed for pregnancy and lactation, and the minimizing of carbonated beverages.

Any dietary source of calcium will count toward the child’s daily intake, but low-fat milk is clearly the most efficient and readily available. Lactose-free milk, soy and rice drinks have recently become more easily obtainable and less expensive.

Parents should contact their child’s pediatrician for specific details about calcium consumption or questions regarding supplements in a chewable form.


  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC. National Academy Press; 1997.
  2. National Institutes of Health, Consensus Development Conference Statement, June 6-8, 1994.
  3. USDA 1994 Continuing Survey of Food Intakes by Individuals.
  4. Third National Health and Nutrition Examination Survey - NHANES III.
Written by Julian Huang, MD