Two new studies published today in the online version of Pediatrics indicate that our nation’s children have very low levels of vitamin D, increasing their risk of developing cardiovascular disease and diabetes later in life.
These findings support researchers concern that vitamin D deficiency was a growing problem among youth and certain minority groups. As the health care debate wages on, the long-term health implications of this finding is a wake-up call for policy makers, pediatricians and parents.
A deficiency in vitamin D leads to rickets – a condition that disturbs bone formation. This condition is relatively rare today because since the 1930s, the government has mandated that milk be fortified with vitamin D. Other food sources of vitamin D include salmon, mackerel, sardines, cod liver oil and some fortified cereals.
The body manufactures vitamin D through the action of sunlight. People with dark skin, who don’t get outside often or live in Northern climates where it is less sunny, are more apt to become vitamin D deficient.
“Several studies had found a high prevalence of vitamin D deficiency in specific populations of children, but no one had examined this issue nationwide,” says study leader Michal L. Melamed, M.D., assistant professor of medicine and of epidemiology & population health at Albert Einstein College of Medicine of Yeshiva University.
To determine the extent of vitamin D deficiency in children, Dr. Melamed and her team analyzed data on 6,275 children, ages 1 to 21, who participated in the 2001-2004 National Health and Nutrition Examination Survey (NNHANES)†.
The researchers found that 9 percent or 7.6 million children were vitamin D deficient (defined as less than 15 ng/mL of blood) and another 61 percent or 50.8 million were vitamin D insufficient (defined as 15 to 29 ng/mL). The researchers were shocked by the large number of children deficient in vitamin D.
The children most likely to be vitamin D deficient were older, female, African-American, Mexican-American, obese, drank milk less than once a week or spent more than four hours a day watching television, playing videogames or using computers.
Low levels of vitamin D were also associated with higher parathyroid hormone (a marker for bone health) and blood pressure, and lower calcium levels and HDL or “good” cholesterol levels – independent risk factors for cardiovascular disease.
Not surprisingly, children who took a vitamin D supplement (400 IUs per day) were less likely to have a deficiency. However, just four percent of the study group used supplements.
More parents may start giving their children supplements. In November 2008, the American Academy of Pediatrics updated its vitamin D guidelines for children from 200 IUs to 400 IUs per day in supplement form. This was based on the vitamin’s high safety profile, limited natural dietary sources, and the increased risk of skin cancer from more sunshine exposure.
In a companion study, also published in the August issue of Pediatrics, researchers focused on the relationship of low serum vitamin D levels and cardiovascular risk factors in adolescent children.
Researchers analyzed data provided by 3,577 adolescents aged 12 to 19 years who participated in the 2001-2004 National Health and Nutrition Examination Survey.
Low serum vitamin D levels were associated with African American adolescents and those with overweight status and abdominal obesity.
After adjustment for demographics, socioeconomic status and physical activity, low serum vitamin D levels in U.S. adolescents was strongly associated with hypertension, hyperglycemia and metabolic syndrome, independent of overweight status. Each of these medical disorders increases the risk of developing cardiovascular disease and diabetes.
†NNHANES is a survey research program conducted by the National Center for Health Statistics (NCHS) to assess the overall health and nutritional status of adults and children in the U.S. and to track changes over time. The survey is unique in that it combines interviews and physical examinations.
The Bottom Line
As the researchers pointed out, the reason for vitamin D deficiencies in today’s youth is pretty simple – diet and lifestyle.
Today, kids drink more soda and far less milk. Most children don’t eat much fish, much less the kind that is a good source of vitamin D. And, unlike our grandmother’s, moms do not give their kids cod liver oil.
Lifestyle is not much better. Kids today spend more time indoors playing or working on their computer. They spend less time outdoors. When they are in the sunshine, parents lather on the sunscreen so that they have less of an opportunity to manufacture vitamin D on their own.
The answer is easy yet difficult – improved diet and lifestyle. If kids can’t be encouraged to eat the foods high in vitamin D (including many breakfast cereals that are contain a staggering amount of sugar), then their diets should be supplemented with 400 IUs of vitamin D daily.