Vitamin D insufficiency among free-living healthy young adults

Abstract

Long-term vitamin D insufficiency can cause secondary hyperparathyroidism and osteomalacia (1). In addition, there is increasing evidence that vitamin D may protect against common cancers, such as cancer of the colon (–4), prostate (5), and breast (6). Young adults aged 17 to 35 years drink inadequate amounts of milk (7) and are concerned about exposure to the sun because of the fear of developing skin cancer (8,9), which increases the risk of vitamin D insufficiency (10). We sought to examine the prevalence of vitamin D insufficiency in a group of free-living healthy young adults, consisting of mostly health care professionals, in Boston, Massachusetts.

Figure 1

The relation between 25-hydroxyvitamin D and parathyroid hormone levels. Serum levels of 25-hydroxyvitamin D were inversely correlated with parathyroid hormone levels (r = 0.40, P <0.001).

Figure 2

Seasonal variation in 25-hydroxyvitamin D levels by age group. Means are presented with error bars representing the SD. Subjects in the end-of-summer groups had higher 25-hydroxyvitamin D levels. The dashed horizontal line represents the minimum level of 25-hydroxyvitamin D considered to be vitamin D sufficient (12). There was a significant difference in the mean serum 25-hydroxyvitamin D levels in the 18- to 29-year-old group when comparing the end-of-winter with the end-of-summer groups (P <0.01).

Figure 3

Percentage of subjects in the four age groups who were vitamin D deficient (25-hydroxy vitamin D level ≤20 ng/mL) at the end of winter and at the end of summer. There was a significant difference in the proportion of subjects with vitamin D insufficiency between the end-of-winter and end-of-summer groups (P <0.05).