A Plague of Brittle Bones Health Article

It looked like a trend, and a dangerous one at that. In patient after patient, Catherine M. Gordon, a pediatric endocrinologist and director of the Bone Health Center at Children's Hospital in Boston, saw surprisingly low blood levels of vitamin D, the nutrient essential for absorbing calcium from food to build and strengthen bones. She wondered if the deficiency, perhaps caused by poor eating habits and indoor activities that prevented exposure to sunlight, could be blamed for some of the youths' bone problems.

As a follow-up, Gordon investigated 307 adolescents without bone problems and confirmed her suspicions. At a time when teenagers should be building bone mass, Gordon observed widespread shortfalls: almost one-fourth of the teens in her study had evidence of vitamin D deficiency. "At least 50 percent of bone density is laid down during the teenage years," Gordon explains, "and this is the critical time for acquiring one's peak bone mass—the bone bank for life."

When young children lack vitamin D they can develop osteomalacia and rickets—spongy bones with softer structure that can cause bowed legs. But if vitamin D deficiency occurs instead during the teenage years, after development of normal bone structure, osteoporosis produces weaker, brittle bones that are more prone to fracture. In fact, a separate study from 2004 found a 42 percent increase in bone fractures in adolescent girls and boys over the last 30 years.

Although Gordon focuses on children and adolescents, her findings have an impact at any stage of life. Since we all lose bone mass as we age, researchers worry that early failure to stockpile reserves could result in greater risk of osteoporosis later in life. More than 44 million adults in the United States have, or are at risk of developing, this debilitating condition. Even if you take calcium supplements, insufficient vitamin D can diminish calcium absorption by the body.

Unlike most nutrients, vitamin D is a hormone and is synthesized by the body through a process that depends upon the ultraviolet rays of sunlight. Brief exposure of the face and arms to ultraviolet light is the most reliable source of vitamin D in spring and summer. For Caucasians, a daily dose takes 10 minutes in the sun; for African Americans, 15 to 20 minutes. "We probably get that going out to the store and walking in between buildings. It doesn't take much," Gordon advises. The challenge for people north of 40 degrees latitude (the top half of the U.S. and Canada) is that there isn't enough ultraviolet light from November through February to produce vitamin D, no matter how brightly the sun shines.

Vitamin D can also enter the body through foods, although few—namely fatty fish—contain D naturally. Some foods are fortified with D, including most milk, many breakfast cereals and some juices—check the labels.

Gordon suspects that teenagers' poor eating habits and sedentary lifestyle play a large role in vitamin D deficiency: "Teens are substituting less healthy choices like soda for milk, and they may not be outside as much because of computers and television."

Vitamin D on the Menu

Salmon (3 1/2 oz.) 360 IU

Mackerel (3 1/2 oz.) 345 IU

Sardines (3 1/2 oz.) 270 IU

Fortified juice (8 oz.) 100 IU

Milk (8 oz.) 98 IU

Fortified breakfast

cereal (3/4 cup) 40-50 IU

Egg yolk 25 IU

Essential D at Any Age

Recommended Daily Allowances (International Units)

Infant-50 years 200 IU

51-70 years 400 IU

71 years and up 600 IU

As we age, our skin's ability to make vitamin D, crucial to calcium uptake, declines.

Bottom Line:

Vitamin D is essential for the absorption of calcium from foods. Even moderate deficiencies carry serious long-term consequences. For optimal health choose foods rich in D and consider taking a multivitamin or supplement with the RDA that fits your age.

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