becomes. Calcium from supplements should be spaced
out during the day for maximum absorption.Vitamin D. The presence of vitamin D improves cal-
cium absorption. Vitamin D deficiency can worsen
calcium deficiency.
Plant products. Phytic found in beans and oxalic acid
found in spinach and leafy greens decrease the amount
of calcium absorbed from those foods, but does not
affect the absorption of calcium from other foods
present at the same time in the intestine. Fiber such
as wheat bran also reduced calcium absorption.
Prescription medications can also affect or be
affected by the absorption of calcium. These include:
digoxin
fluroquinolones
levothyroxine
tetracycline antibiotics
anticonvulsants
thiazide-type diuretics
glucacorticoids
mineral oil
stimulant laxatives
antacids
People taking these drugs should check with their
healthcare provider or pharmacist about potential adjust-
ments in their medications or calcium intake.
ComplicationsNo complications are expected when healthy peo-
ple take calcium in amounts equal to the AI level and
less than the UL level. Some people experience gas,
nausea, and abdominal discomfort from calcium sup-
plements. Taking the supplement with meals, taking
smaller doses spread out over the day, or changing the
type of supplement usually solves this problem. Com-
plications of excess calcium and calcium deficiency are
discussed above.
Parental concernsBuilding strong bones starts in childhood, and
parents should be aware of how much calcium their
child needs compared to how much he or she is getting.
As children get older they tend to replace milk in their
diet with juice, bottledwater, and especially carbo-
nated soft drinks. This leads to large calcium deficien-
cies during adolescence. Parents should monitor their
child’s diet and encourage calcium supplements if they
cannot induce their adolescents to eat more dairy
products and other calcium-rich food.
Resources
BOOKS
Fragakis, Allison.The Health Professional’s Guide to Popu-
lar Dietary Supplements. Chicago: American Dietetic
Association, 2003.
Gaby, Alan R., ed.A-Z Guide to Drug-Herb-Vitamin Inter-
actions Revised and Expanded 2nd Edition: Improve
Your Health and Avoid Side Effects When Using Com-
mon Medications and Natural Supplements Together.
New York: Three Rivers Press, 2006.
Lieberman, Shari and Nancy Bruning.The Real Vitamin and
Mineral Book: The Definitive Guide to Designing Your
Personal Supplement Program,4th ed. New York:
Avery, 2007.
Pressman, Alan H. and Sheila Buff.The Complete Idiot’s
Guide to Vitamins and Minerals,3rd ed. Indianapolis,
IN: Alpha Books, 2007.
Rockwell, Sally.Calcium Rich & Dairy Free: How to Get
Calcium Without the Cow.Pomeroy, WA: Health
Research Books, 2005.
Rucker, Robert B., ed.Handbook of Vitamins.Boca Raton,
FL: Taylor & Francis, 2007.
PERIODICALS
Familydoctor.org. ‘‘Vitamins and Minerals: What You
Should Know.’’American Family Physician.December
2006.<http://familydoctor.org/863.xml>
ORGANIZATIONS
American Dietetic Association. 120 South Riverside Plaza,
Suite 2000, Chicago, Illinois 60606-6995. Telephone:
(800) 877-1600. Website:<http://www.eatright.org>
International Food Information Council. 1100 Connecticut
Avenue, NW Suite 430, Washington, DC 20036. Tele-
phone: 202-296-6540. Fax: 202-296-6547. Website:
<http://ific.org>
Linus Pauling Institute. Oregon State University, 571
Weniger Hall, Corvallis, OR 97331-6512. Telephone:
(541) 717-5075. Fax: (541) 737-5077. Website:<http://
lpi.oregonstate.edu>
National Institutes of Health Osteoporosis and Related
Bone Diseases National Resource Center. 2 AMS
Circle, Bethesda, MD 20892-3676 Telephone: (800)
624-BONE or (202)223-0344. TTY: (202) 293-2356.
Fax: (202)466-4325. Website:<http://www.niams.nih
.gov/bone/>
Office of Dietary Supplements, National Institutes of
Health. 6100 Executive Blvd., Room 3B01, MSC 7517,
Bethesda, MD 20892-7517 Telephone: (301)435-2920.
Fax: (301)480-1845. Website:<http://dietary-
supplements.info.nih.gov>
OTHER
Harvard School of Public Health. ‘‘Calcium & Milk.’’ Har-
vard University, December 13, 2004.<http://www
.hsph.harvard.edu/nutritionsource/calcium.html>
Mayo Clinic Staff. ‘‘Calcium supplements: Do Men Need
Them Too?’’ MayoClinic.com, January 4, 2007.<http://Calcium