Most people know of the childhood autism and asthma epidemics that started in the 1980’s, but few people know of the third childhood epidemic, one that also began in the 1980s, and that is the childhood autoimmune epidemic. The list includes children with juvenile rheumatoid arthritis, juvenile lupus and juvenile diabetes. Why are so many of our children getting these diseases, diseases that were rare in childhood in the 1950s and 60s and that now literally ravage so many kids?
And yet a fourth childhood epidemic is that of type 2 diabetes, a situation in which insulin has a hard time getting into cells, and in effect, sugar has a hard time getting into cells as well. Thus, sugar goes up in the blood. The key pathology in type 2 diabetes is insulin resistance, where the cells do not respond to insulin optimally. Obesity is associated with insulin resistance but is probably not the actual cause. What is causing so many children to develop insulin resistance?
Dr. Andrea Kelly and colleagues, at the Children’s Hospital of Philadelphia, went a long way toward answering the question several months ago.
The group studied vitamin D levels and markers of diabetes, including insulin levels and insulin resistance in 85 children. In what turned out to be very important, they had 24 kids with levels above 30 ng/ml. This group had an average level of 40 ng/ml. The other 61 children had levels lower than 30 ng/ml, including 14 children with levels below 10 ng/ml. That’s right, over 15% of children had levels lower than the dangerous threshold of 10 ng/ml; this in the United States in 2011. We should be ashamed.
The remarkable thing about Dr. Kelly’s study was the large differences between the kids with the lowest vitamin D levels compared to the kids with the highest levels. The measurement of insulin resistance was 0.9 for the kids with the highest levels but 6.6 for the kids with low levels, a seven-fold difference (the lower the better). The numbers for insulin itself (also the lower the better) were equally dramatic: 4.3 for the children with the highest vitamin D level, 27 for the kids with lowest vitamin D levels. The differences in the blood sugar were not as dramatic but were statistically significant.
Dr. Kelly concluded,
“Vitamin D deficiency is prevalent among children and adolescents, but the long-term burden of vitamin D deficiency may not be limited to bone health. . . Given the obesity epidemic among children and the recognition that many adult disease have their origin in childhood, the possibility that low vitamin D promotes insulin resistance holds promise for a simple intervention by which to decrease the risk of type 2 diabetes.”
This study got it right because they had some children with close to adequate levels, average of 40 ng/ml. Studies that compare 10 ng/ml with 20 ng/ml are often going to miss an effect on anything but bone.
Congratulations to Dr. Kelly and the entire group. We agree: American children need to have their vitamin D deficiencies treated.