Limited research has been completed on the importance of vitamin D for children and teenagers. Vitamin D is important for the achievement of genetically pre-programmed peak bone mass. although most commonly observed in infancy, can also occur during the pubertal growth spurt and adolescence. Bowing of the legs, muscle weakness, lower limb and back pain are the most common symptoms of rickets that occurs during adolescence.
Data from national surveys in the UK, USA and New Zealand show that the prevalence of inadequate vitamin D status is more of a concern for adolescents than for children. Data from the National Diet and Nutrition Survey (NDNS) observed that greater than 40% of UK adolesents had s25(OH)D below 50nmol/l (Prentice, 2007). In Northern Ireland, 36% of adolescent boys and girls (n >1000) had a serum 25(OH)D concentration below 50nmol/l (). A recent study, in Philadelphia, showed 55% of otherwise healthy children aged 6-21-y (n = 382) had serum 25(OH)D concentrations below 75nmol/l (Weng et al, 2007).
There is increasing evidence linking low vitamin D status with the increased risk of chronic diseases such as , and , which originate in early adulthood. Much of this evidence is based on studies completed in adults, while far less is known about the consequences of poor vitamin D status during childhood and adolescence. However, a review by Holick (2006), highlighted that living at latitudes above 35 degrees for the first 10 years of your life increases your risk of multiple sclerosis by 100%, as well as increasing the risk of several other autoimmune diseases. Research has also indicated that children with Type 1 diabetes mellitus were more than 3 times likely to have vitamin D deficiency (25(OH)D <50nmol/l) compared with controls (Greer et al, 2007). In another study, where Finnish children who's vitamin D consumption was recorded during their first year of life were followed for the next 31 years, it was demonstrated that vitamin D supplementation during the first year of life reduced the risk of developing type 1 diabetes mellitus by 80% (Hyponnen et al, 2001).
The serum 25(OH)D level in which PTH plateau’s or levels off is often used as the indicator for sufficient vitamin D status in the elderly. Serum concentrations of PTH are often elevated in children and adolescence due to an increased rate of bone modeling, therefore high PTH concentrations may not be detrimental for bone health and the various definitions used for the adult population, may be questionable for children and adolescents. , (in press) showed low vitamin D status to be related to lower bone mass and higher bone turnover in adolescent girls (aged 12 and 15 years), but not boys.