Triggered by sunlight, vitamin D is made in the skin. People who spend little time outside or who use sunscreen diligently tend to not make a sufficient amount of vitamin D. People who live in colder climates or in areas where sunlight is a rarer event tend to have low levels of serum vitamin D. In addition, people with darker skin tones need more sunlight to make adequate amounts of vitamin D.
Vitamin D is found in certain foods, such as fatty fish, red meat, liver, cod liver oil, and eggs. In the United States, milk is often fortified with vitamin D. An 8-ounce glass of milk has about 100 IU of vitamin D. But, large numbers of people of all ages fail to make enough from the sun and/or consume enough vitamin D in their diet. For teens and young adults, who are still building the bones they will need for a lifetime, the lack of sufficient vitamin D needs to be addressed.
Vitamin D deficiency may be diagnosed through a simple blood test called 25 hydroxyvitamin D or 25(OH)D. Serum concentrations above 50 nmol/L are considered normal. In general, teens should take in about 600 IU per day. Potential vitamin D supplementation is a good topic to address with medical providers. 1
In a study published in 2014 in the European Journal of Clinical Investigation, researchers from Italy evaluated the association between levels of vitamin D and the extent of coronary artery disease in patients undergoing coronary angiography, a medical test that uses dyes and special x-rays to see inside coronary arteries. Of the 1,484 patients in the cohort, a stunning 70.4 percent had low levels of vitamin D. Those with the lowest levels of vitamin D appeared to have the most coronary artery disease. “The association between low vitamin D levels and CAD reached a statistical significance.” Patients with very low levels of vitamin D should be considered at increased risk for cardiovascular disease. The researchers concluded that there should be more research on this topic. “Additional studies are needed to evaluate the potential benefits of vitamin D supplementation on the prevention of CAD and its progression.” 2
In a study published in 2012 in the Journal of Clinical Endocrinology & Metabolism, researchers based in Dallas, Texas, determined the prevalence of vitamin D deficiency in children referred to an obesity clinic in north Texas and compared that prevalence to similar non-overweight children. They also examined associations between levels of vitamin D and type 2 diabetes. The cohort consisted of 411 obese children between the ages of 6 and 16 years and 89 non-overweight children, with the same age range. All the data were collected in 2009 and 2010. When compared to the normal weight children, the researchers found that the obese children were far more likely to have lower levels of vitamin D. Moreover, lower levels of Vitamin D were associated with risk factors for type 2 diabetes, such as insulin resistance, in obese children. “Thus, low 25(OH)D levels may play a role in the pathophysiology of impaired glucose tolerance in obese children.” 4
In a study published in 2015 in the journal European Child & Adolescent Psychiatry, researchers from China and the Netherlands wanted to learn if vitamin D played a role in the etiology of autism spectrum disorder. (Autism spectrum disorder is a brain disorder characterized by deficits in social interaction, verbal and nonverbal communication, and restricted and repetitive behaviors.) The researchers conducted a meta-analysis that included 11 studies with 870 children with some type of autism spectrum disorder and 782 healthy controls. All the children were between the ages of 2 and 16 years. The researchers found that compared to the controls, the people with autism spectrum disorders had significantly lower levels of vitamin D. And, they suggested that lower levels of vitamin D may place people at increased risk for autism spectrum disorders. 6
In fact, in an article published in 2015 in the journal Pediatrics, researchers from China and the Netherlands described the case of a 32-month-old boy from China with autism spectrum disorder and vitamin D deficiency. He appeared to have a number of autism symptoms. “No urge for social interaction, no response to facial expression or to other people, no social interactional smiling, not following instructions from his parents, no response when somebody calls his name, avoidance of eye contact and physical contact, strange gestures.” The toddler also had temper tantrums, attacked other children, and hurt himself when he banged his head against objects. Upon testing, his medical providers found that he had very low levels of serum vitamin D. As a result, he received both IV and oral vitamin D supplementation. After two months, the parents reported noticeable improvements in behavior. The child responded when his name was called and was no longer preoccupied with running in circles. Self-injury had almost stopped, and he allowed his parents to hold him in their arms. Because no other medical abnormalities were found other than vitamin D deficiency, “the marked improvement in the relatively brief period of treatment that was observed in this case appears to be related to vitamin D supplementation.” 7
In a study published in 2015 in the online journal PLoS ONE, researchers based in Saudi Arabia wanted to learn more about the rates of vitamin D deficiency among Arab adolescent and adult males and females. The cohort consisted of 1,187 males and 1,038 females between the ages of 13 and 17 years and 368 men and 462 women between the ages of 18 and 50 years. Sizeable numbers of these seemingly healthy people had some level of vitamin D deficiency. Almost half of the female teens and almost one-fifth of the male teens had a deficiency. Almost two-fifths of the women and one-fifth of the men were deficient. In addition to the high prevalence of vitamin D deficiency, the researchers found an association between low vitamin D levels in male teens and cardiometabolic risk factors. According to the researchers, this finding “indicated a sex and age-related disadvantage for boys with low vitamin D status and challenges the extra-skeletal protection of vitamin D correction in adolescent females.” 9
1. Vitamin D Council, www.vitmindcouncil.org.
2. Monica Verdoia, Alon Schaffer, Chiara Sartori et al., “Vitamin D Deficiency Is Independently Associated with the Extent of Coronary Artery Disease,” European Journal of Clinical Investigation 44, no. 7 (2014): 634-42.
3. Kung-Ting Kao, Nobia Abidi, Sanjeeva Ranasinha et al., “Low Vitamin D Is Associated with Hypertension in Paediatric Obesity,” Journal of Paediatrics and Child Health 51, no. 12 (2015): 1207-13.
4. Micah L. Olson, Naim M. Maalouf, Jon D. Oden et al., “Vitamin D Deficiency in Obese Children and Its Relationship to Glucose Homeostasis,” Journal of Clinical Endocrinology & Metabolism 97, no. 1 (2012): 279-85.
5. R. E. Allen, A. D. Dangour, A. E. Tedstone, and Z. Chalabi, “Does Fortification of Staple Foods Improve Vitamin D Intakes and Status of Groups At Risk of Deficiency? A United Kingdom Modeling Study,” American Journal of Clinical Nutrition 102, no. 2 (2015): 338-44.
6. T. Wang, L. Shan, L. Du et al., 2015. “Serum Concentration of 25-Hydroxyvitamin D in Autism Spectrum Disorder: A Systematic Review and Meta-Analysis,” European Child & Adolescent Psychiatry 25, no. 4 (April 2016): 341-50.
7. Feiyong Jia, Bing Wang, Ling Shan et al., “Core Symptoms of Autism Improved After Vitamin D Supplementation,” Pediatrics 135, no. 1 (2015): e196-e198.
8. Eleni Linos, Elizabeth Keiser, Matthew Kanzler et al., “Sun Protective Behaviors and Vitamin D Levels in the US Population: NHANES 2003-2006,” Cancer Causes & Control 23, no. 1 (2012): 133-40.
9. Nasser M. Al-Daghri, Yousef Al-Saleh, Naji Aljohani et al., “Vitamin D Deficiency and Cardiometabolic Risks: A Juxtaposition of Arab Adolescents and Adults,” PLoS ONE 10, no. 7 (2015): e0131315.
10. T. Winzenberg, S. Powell, K. A. Shaw, and G. Jones, “Effects of Vitamin D Supplementation on Bone Density in Healthy Children: Systematic Review and Meta-Analysis,” BMJ 342 (2011): c7254.
Al-Daghri, Nasser M., Yousef Al-Saleh, Naji Aljohani et al. “Vitamin D Deficiency and Cardiometabolic Risks: A Juxtaposition of Arab Adolescents and Adults.” PLoS ONE 10, no. 7 (2015): e0131315.
Allen, R. E., A. D. Dangour, A. E. Tedstone, and Z. Chalabi. August 2015. “Does Fortification of Staple Foods Improve Vitamin D Intakes and Status of Groups at Risk of Deficiency? A United Kingdom Modeling Study.” American Journal of Clinical Nutrition 102, no. 2 (2015): 338-44.
Jia, Feiyong, Bing Wang, Ling Shan et al. “Core Symptoms of Autism Improved After Vitamin D Supplementation.” Pediatrics 135, no. 1 (2015): e196-e198.
Kao, Kung-Ting, Nobia Abidi, Sanjeeva Ranasinha et al. “Low Vitamin D Is Associated with Hypertension in Paediatric Obesity.” Journal of Paediatrics and Child Health 51, no. 12 (2015): 1207-13.
Linos, Eleni, Elizabeth Keiser, Matthew Kanzler et al. “Sun Protective Behaviors and Vitamin D Levels in the US Population: NHANES 2003-2006.” Cancer Causes & Control 23, no. 1 (2012): 133-40.
Olson, Micah L., Naim M. Maalouf, Jon D. Oden et al. “Vitamin D Deficiency in Obese Children and Its Relationship to Glucose Homeostasis.” Journal of Clinical Endocrinology & Metabolism 97, no. 1 (2012): 279-85.
Pilz, Stefan, Martin Gaksch, Katharina Kienreich et al. “Effects of Vitamin D on Blood Pressure and Cardiovascular Risk Factors: A Randomized Controlled Trial.” Hypertension 65 (2015): 1195-201.
Verdoia, Monica, Alon Schaffer, Chiara Sartori et al. “Vitamin D Deficiency Is Independently Associated with the Extent of Coronary Artery Disease.” European Journal of Clinical Investigation 44, no. 7 (2014): 634-42.
Wang, T., L. Shan, L. Du et al. “Serum Concentration of 25-Hydroxyvitamin D in Autism Spectrum Disorder: A Systematic Review and Meta-Analysis.” European Child & Adolescent Psychiatry 25, no. 4 (April 2016): 341-50.
Winzenberg, T., S. Powell, K. A. Shaw, and G. Jones. “Effects of Vitamin D Supplementation on Bone Density in Healthy Children: Systematic Review and Meta-Analysis.” BMJ 342 (2011): c7254.
Vitamin D Council. www.vitamindcouncil.org .