Building Strong Bones
Was Tiny Tim, the lovable crippled child in Charles Dickens's classic A Christmas Carol, suffering from the vitamin D-deficiency bone disease called rickets?
One expert argues that it's likely, since nineteenth-century London was, as he puts it, "miserable." Any sunlight capable of piercing the English gloom was almost certainly trapped by industrial smog back then.
Sunlight is not the only potential source of rickets-preventing vitamin D, of course. But the Cratchit family's meager diet was hardly healthful enough to prevent a case of the infamous disease that crippled so many nineteenth-century children.
Bah, humbug, retort other experts. The Cratchit child clearly had some other crippling disease.
That the experts amuse themselves by debating Tiny Tim's condition says a lot about the frequency of rickets today. Aside from cases in which people avoid certain foods or the sun for dietary or religious reasons, this condition, called common rickets in children and osteomalacia in adults, is more a medical curiosity than an ongoing concern.
Almost Gone, but Not Forgotten
Still, doctors have to be prepared to diagnose either. Not too long ago, at Children's Hospital of New Jersey in Newark, doctors were looking at the
x-rays of a 15-month-old girl suffering from respiratory problems when they discovered that bones in her shoulder were frayed. This is a common sign of rickets, says Robert Rapaport, M.D., director of the Division of Pediatric Endocrinology and Metabolism at the University of Medicine and Dentistry of New Jersey/New Jersey Medical School in Newark.
Further investigation revealed that the child came from a strict religious home where she wore clothing that covered all but her nose and forehead. The combination of her manner of dress and the absence of dairy products in her diet contributed to her condition, reports Dr. Rapaport.
An unusual case, perhaps, but "these kinds of cases demonstrate that
vitamin D-deficiency rickets is still around," says Dr. Rapaport. "Both health care professionals and parents need to be educated about factors that predispose to rickets and about measures that can prevent its development."
Without sunlight (vitamin D is synthesized in the skin by the action of ultraviolet light) or dairy products, both sources of vitamin D, young, growing bones are unable to perform a task known as mineralization, which is the process that adds minerals needed for bone development, says Binita R. Shah, M.D., professor of clinical pediatrics and director of pediatric emergency medicine at the State University of New York Health Science Center at Brooklyn. Dark skin, colder climates, abundant clothing and industrial pollution are all potential barriers to vitamin D production by the skin, says Dr. Shah.
Boning Up on Vitamin D
Bone is a dynamic organ that is constantly being formed and re-formed, says Dr. Shah. Vitamin D is essential for bone formation and mineralization. It also ensures that there are proper amounts of calcium and phosphorus on hand for bone growth. It does this in three ways: first, by making certain that these minerals are absorbed in the intestines; second, by bringing calcium from bones into the blood; and third, by aiding the reabsorption of calcium and phosphorus by the kidneys, says Dr. Shah.
"When you see a case of rickets, the body is desperately trying to make bone, but adequate calcium and phosphorus aren't available. It's a poor effort, resulting in unmineralized bone accumulation," says Dr. Shah.
As a result, a child with rickets will have ankles and wrists that flare, with noticeable knobby bumps, and weakened leg bones that bow under the child's own weight. Other symptoms include a lack of muscle tone, a disproportionately large head and forehead and delayed infant milestones such as sitting up, standing and the appearance of teeth.
Prevention of rickets and osteomalacia is as simple as including good sources of vitamin D, such as fish (especially sardines and salmon) and fortified milk, in the diet. Dr. Shah recommends human milk for infants, but in this case, she stresses the importance of vitamin D supplementation, since human milk contains little vitamin D. For infants who are not given human milk, infant formula contains all of the necessary nutrients. Also, fortified whole milk is a very important part of an infant's diet, notes Dr. Shah. Since fortified milk is important for adults as well, she adds, skim milk may be a wise choice for them.
Because of fortification, an eight-ounce glass of milk provides about 100 international units of vitamin D. The Daily Value is 400 international units. Experts say that taking more than 600 international units of vitamin D a day can be toxic, with symptoms that may include high blood pressure, kidney failure and coma. For this reason, daily doses exceeding 600 international units should be taken only under medical supervision.
For confirmed rickets cases, Dr. Shah prescribes something called stosstherapy, a form of treatment that provides a total of 600,000 international units of vitamin D, given in a single day in six divided doses. This amount of vitamin D is highly toxic and should be taken only under the supervision of a physician. Used more often in Europe, stosstherapy is preferred when there's doubt whether a child will continue to get appropriate amounts of vitamin D to treat rickets. "This kind of therapy not only heals the rickets but also maintains vitamin D levels for three months," says Dr. Shah. Another benefit: Doctors know in four to seven days whether the rickets is caused by diet or another factor, such as heredity.
Prescriptions for Healing
Because vitamin D is so readily available from sunshine and fortified milk products, rickets, a vitamin D-deficiency disease, is relatively rare in this country. Here's what doctors recommend for both prevention and treatment.
Nutrient Daily Amount
Vitamin D 400 international units
Vitamin D 600,000 international units, taken as 6 divided doses (administered in 1 day under the supervision of a doctor)
MEDICAL ALERT: Doses of more than 600 international units of vitamin D a day can be toxic. Symptoms may include high blood pressure, kidney failure and coma. Vitamin D in such high daily doses should be taken only under the supervision of your doctor.